CN203812253U - A fingerprint information detection circuit based on an electric charge injection mode - Google Patents
A fingerprint information detection circuit based on an electric charge injection mode Download PDFInfo
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Abstract
The utility model relates to chip design, and discloses a fingerprint information detection circuit based on an electric charge injection mode. The fingerprint information detection circuit based on the electric charge injection mode includes a reset unit, a feedback unit, an amplification unit and a source following unit. The reset unit is connected with both the feedback unit and the amplification unit. The feedback unit is connected with the amplification unit. The amplification unit is connected with the source following unit. A reset tube in the reset unit stores electric charges when the reset tube is in conduction and the feedback unit resets. When the reset tube is cut off, the stored electric charges are injected into the feedback unit and the amplification unit. The feedback unit receives the electric charges, and outputs a generated second voltage signal to the source following unit when fingerprint information is detected to exist. The amplification unit amplifies the received signal and then outputs the signal to the source following unit. The source following unit carries out level translation on the received signal and then outputs a first voltage signal; and the first voltage signal carries detected fingerprint information. The fingerprint information detection circuit based on the electric charge injection mode of the utility model enables an area, which is occupied by a circuit, of a chip to be reduced and enables chip costs to be saved.
Description
Technical field
The utility model relates to chip design, particularly a kind of finger print information testing circuit based on charge injection mode.
Background technology
To personal information differentiate and the biological characteristic identified normally by physiological characteristic (such as, hair, fingerprint, blood etc.) realize.When which kind of physiological characteristic of choice for use, can be from the different aspect consideration of compromise, as production cost, process complexity, reliability, comfortableness etc.And at this wherein, fingerprint is the most reliable feature.Although its characteristic is original in style, in individual consumer market, to the application of fingerprint, not also very ripe, be subject on the one hand the impact of Production design, be also subject on the other hand the restriction of expensive factor.
At present, the principle that fingerprint inductor part is used relates generally to optics, integrated pressure, electric capacity etc.Wherein, the factor that the fingerprint identification unit of optical imagery restricts its application is that produced volume ratio is larger, and requires surface to keep clean; The key constraints of integrated pressure sensing unit is the superelevation cost that non-mainstream technology is brought; And fingerprint detection circuit based on capacitive sensing unit mode can well be evaded the shortcoming of first two mode, its general circuit structure as shown in Figure 1, comprises signal input unit, reset unit, amplifying unit, feedback unit and source and follows unit.
In Fig. 1,101 is signal input unit, and 102 is reset unit, and 103 is amplifying unit, and 104 is feedback unit, and 105 for following unit in source.
But the shared chip area of foregoing circuit is larger, increased the cost of chip.
In addition, the voltage signal that the clock feed-through effect that reset unit produces and charge injection effects circuit are exported, affects the result of fingerprint detection.
Utility model content
The purpose of this utility model is to provide a kind of finger print information testing circuit based on charge injection mode, improves the utilization factor of reset transistor, and the area that makes circuit take chip is reduced, and saves the cost of chip; Meanwhile, purifying charge source.
For solving the problems of the technologies described above, the utility model provides a kind of finger print information testing circuit based on charge injection mode, comprises amplifying unit and unit is followed in source; Described amplifying unit is followed unit with described source and is connected; Described amplifying unit exports described source to after the signal of reception is amplified and follows unit; Described source is followed unit the signal receiving is carried out exporting the first voltage signal after level translation, and wherein, described the first voltage signal carries the finger print information of detection; Also comprise reset unit, feedback unit;
Wherein, described feedback unit exports the second voltage signal of generation to described source and follows unit when finger print information being detected;
Described reset unit is all connected with described feedback unit, described amplifying unit; Described feedback unit is connected with described amplifying unit; The input end of described reset unit is used for inputting reset signal;
When described reset signal is high level, reset transistor conducting stored charge that described reset unit is built-in reset to described feedback unit simultaneously; When described reset signal switches to low level by high level, the cut-off of described reset transistor, and by the charge injection of storage to described feedback unit and described amplifying unit;
Described feedback unit receives described electric charge, and when finger print information being detected, exports described second voltage signal to described source and follow unit.
The utility model embodiment in terms of existing technologies, is to produce iunjected charge by the built-in reset transistor of reset unit, does not need to set up in addition input block and produces separately iunjected charge.Specifically, the finger print information testing circuit based on charge injection mode in the utility model comprises amplifying unit, unit, reset unit and feedback unit are followed in source; Reset unit is all connected with feedback unit, amplifying unit, and feedback unit is connected with amplifying unit, and amplifying unit is followed unit with source and is connected, and the input end of reset unit is used for inputting reset signal; Wherein, feedback unit exports the second voltage signal of generation to source and follows unit when finger print information being detected, amplifying unit exports source to after the signal of reception is amplified and follows unit, source is followed unit the signal receiving is carried out exporting the first voltage signal after level translation, and this first voltage signal carries the finger print information of detection.Key is, when reset signal is high level, and the reset transistor conducting that reset unit is built-in, now, feedback unit is without stored charge, and reset transistor resets to feedback unit; In this simultaneously, reset transistor forms a capacity plate antenna when conducting, stores electric charge; And when reset signal switches to low level by high level, reset transistor cut-off, and by the charge injection of storage to feedback unit and amplifying unit; Feedback unit receives the initial charge that electric charge stores as feedback unit, produces original tertiary voltage signal simultaneously, and when finger print information being detected, exports the second voltage signal of generation to source and follow unit.The utility model utilizes reset transistor when cut-off by charge injection feedback unit just, rather than set up in addition input block and produce separately electric charge to inject feedback unit, thereby the utilization factor that improves reset transistor, the area that makes fingerprint detection circuit take chip is reduced, and saves the cost of chip.In addition, in chip, reset unit also can be placed in the below of feedback unit, and the area that makes finger print information testing circuit based on charge injection mode take chip is further reduced, and further saves chip cost.Meanwhile, inject the electric charge that the electric charge of feedback unit all stores from reset transistor, purifying be injected into the charge source of feedback unit.
In addition, described reset unit comprises the first phase inverter, the second phase inverter, the 3rd phase inverter and a N channel metal-oxide-semiconductor field effect transistor;
The input end of described the first phase inverter is the input end of described reset unit, and output terminal is connected with the input end of described the second phase inverter;
The output terminal of described the second phase inverter is connected with the input end of described the 3rd phase inverter;
The output terminal of described the 3rd phase inverter is connected with the grid of a described N channel metal-oxide-semiconductor field effect transistor;
The source electrode of a described N channel metal-oxide-semiconductor field effect transistor is connected with drain electrode, wherein, and the first output port that described drain electrode is described reset unit;
The first port of described reset transistor is connected with the first output port of described reset unit, the second output port that the second port is described reset unit, and the 3rd port is connected with the output terminal of described the second phase inverter.
Wherein, described reset transistor is described the 2nd N channel metal-oxide-semiconductor field effect transistor;
The source electrode of described the 2nd N channel metal-oxide-semiconductor field effect transistor is the first port of described reset transistor; The drain electrode of described the 2nd N channel metal-oxide-semiconductor field effect transistor is the second port of described reset transistor; The grid of described the 2nd N channel metal-oxide-semiconductor field effect transistor is the 3rd port of described reset transistor.
The channel width of described reset transistor is the twice of the channel width of a described N channel metal-oxide-semiconductor field effect transistor.
According to above-mentioned connection, when input reset signal, reset transistor generation clock feed-through effect and the quantity of electric charge producing because of clock feedthrough are
Q
clk1＝V
clk1W
1C
ov，
Wherein, V
clk1for the clock voltage of reset transistor, W
1for the channel width of reset transistor, C
ovoverlap capacitance for unit width.
Meanwhile, a N channel metal-oxide-semiconductor field effect transistor absorbs the electric charge that reset transistor produces because of clock feedthrough.The one N channel metal-oxide-semiconductor field effect transistor because of the quantity of electric charge that clock feedthrough absorbs is
Q
clk2＝V
clk22W
2C
ov，
Wherein, V
clk2be the clock voltage of a N channel metal-oxide-semiconductor field effect transistor, V
clk2v
clk1through the 3rd phase inverter, obtain the two single spin-echo, W
2be the channel width of a N channel metal-oxide-semiconductor field effect transistor, C
ovoverlap capacitance for unit width.
The channel width of reset transistor is the twice of the channel width of a N channel metal-oxide-semiconductor field effect transistor, i.e. W
1=2W
2so, the electric charge that reset transistor produces because of clock feedthrough is all absorbed because of clock feedthrough by a N channel metal-oxide-semiconductor field effect transistor, make to have eliminated the electric charge producing because of clock feedthrough, make to inject the electric charge that the electric charge of feedback unit all stores from reset transistor, purifying be injected into the charge source of feedback unit.
In addition, described feedback unit ground connection.Like this, when finger touch, point entrained static and be conducted to the earth, make to avoid to cause the reset unit, amplifying unit, the source that are connected with feedback unit to follow unit by electrostatic breakdown because pointing entrained static.
In addition, described feedback unit comprises the first electric capacity, the second electric capacity and the 3rd electric capacity;
The positive pole of described the first electric capacity is connected with the first port of described feedback unit, and negative pole is connected with the second port of described feedback unit;
Wherein, the first port of described feedback unit is connected with the first output port of described reset unit, and the second port of described feedback unit is connected with the second output port of described reset unit;
The positive pole of described the second electric capacity is connected with the first port of described feedback unit, minus earth;
The positive pole of described the 3rd electric capacity is connected with the second port of described feedback unit, minus earth.
This is the composition of feedback unit during without finger touch, and when finger touch, feedback unit also comprises the 4th electric capacity, the 5th electric capacity, the 6th electric capacity and resistance;
The positive pole of described the 4th electric capacity is connected with the first port of described feedback unit, and negative pole is connected with the positive pole of described the 5th electric capacity;
The negative pole of described the 5th electric capacity is connected with the second port of described feedback unit;
The positive pole of described the 6th electric capacity is connected with the negative pole of described the 4th electric capacity, the minus earth of described the 6th electric capacity;
Described resistance one end is connected with the positive pole of described the 5th electric capacity, other end ground connection.
Like this, the first electric capacity and fingerprint are non-linear to the distance of feedback unit, make feedback unit can accurately reflect that because the second voltage signal of finger print information generation being detected fingerprint is to the distance of feedback unit, finally make the first voltage signal of fingerprint detection circuit output can reflect more accurately that fingerprint is to the distance of feedback unit.
Accompanying drawing explanation
Fig. 1 is according to the schematic diagram of finger print information testing circuit of the prior art;
Fig. 2 is according to the schematic diagram of the finger print information testing circuit based on charge injection mode of the utility model the first embodiment;
Fig. 3 be according to the utility model the second embodiment finger print information do not detected time the schematic diagram of the finger print information testing circuit based on charge injection mode;
Fig. 4 be according to the utility model the second embodiment finger print information detected time the schematic diagram of the finger print information testing circuit based on charge injection mode;
Fig. 5 is according to the first structure vertical view of the internal polar plate of the utility model the second embodiment, external polar plate and ground ring;
Fig. 6 is according to the second structure vertical view of the internal polar plate of the utility model the second embodiment, external polar plate and ground ring.
Embodiment
For making the purpose of this utility model, technical scheme and advantage clearer, below in conjunction with accompanying drawing, each embodiment of the present utility model is explained in detail.Yet, those having ordinary skill in the art will appreciate that, in each embodiment of the present utility model, in order to make reader understand the application better, many ins and outs have been proposed.But, even without these ins and outs and the many variations based on following embodiment and modification, also can realize each claim of the application technical scheme required for protection.
The first embodiment of the present utility model relates to a kind of finger print information testing circuit based on charge injection mode, and concrete structure as shown in Figure 2, comprises: unit is followed in reset unit, amplifying unit, feedback unit and source.
Wherein, feedback unit exports the second voltage signal of generation to source and follows unit when finger print information being detected.
As shown in Figure 2, reset unit is all connected with feedback unit, amplifying unit; Feedback unit is connected with amplifying unit; Amplifying unit is followed unit with source and is connected; The input end of reset unit is used for inputting reset signal.
When reset signal is high level, reset transistor conducting stored charge that reset unit is built-in reset feedback unit simultaneously.Specifically, during reset transistor conducting, feedback unit is without stored charge, and reset transistor resets to feedback unit, the electric charge zero clearing that feedback unit stores; Meanwhile, reset transistor forms a capacity plate antenna when conducting, stores electric charge.
When reset signal switches to low level by high level, reset transistor cut-off, and by the charge injection of storage to feedback unit and amplifying unit.
Feedback unit receives electric charge, and when finger print information being detected, exports second voltage signal to source and follow unit.Specifically, feedback unit receives the iunjected charge of reset transistor as the initial charge of feedback unit storage, produces original tertiary voltage signal simultaneously, and this is the voltage signal producing while finger print information not detected; Feedback unit exports the second voltage signal of generation to source and follows unit when finger print information being detected.
Source is followed unit the signal receiving is carried out exporting the first voltage signal after level translation, and this first voltage signal carries the finger print information of detection.
In addition, amplifying unit exports source to after the signal of reception is amplified and follows unit.Specifically, when amplifying unit receives electric charge, input voltage signal changes, and amplifying unit exports source to after the input voltage signal after changing is amplified and follows unit.And the output voltage signal after amplifying is identical with second voltage signal.
Compared with prior art, present embodiment not only utilizes the reset transistor of feedback unit to reset to feedback unit, and, also utilize reset transistor to produce iunjected charge, and do not need to set up in addition input block, do not produce separately iunjected charge, thereby improved the utilization factor of reset transistor, the area that makes fingerprint detection circuit take chip is reduced, save the cost of chip.In addition, in chip, reset unit also can be placed in the below of feedback unit, and the area that makes finger print information testing circuit based on charge injection mode take chip is further reduced, and further saves chip cost.Meanwhile, inject the electric charge that the electric charge of feedback unit all stores from reset transistor, purifying be injected into the charge source of feedback unit.
It is worth mentioning that, each module involved in present embodiment is logic module, and in actual applications, a logical block can be a physical location, can be also a part for a physical location, can also realize with the combination of a plurality of physical locations.In addition, for outstanding innovation part of the present utility model, in present embodiment, the unit not too close with solving technical matters relation that the utility model proposes do not introduced, but this does not show not exist in present embodiment other unit.
The second embodiment of the present utility model relates to a kind of finger print information testing circuit based on charge injection mode.The second embodiment done further refinement on the basis of the first embodiment, provided the concrete structure that unit is followed in reset unit, feedback unit, amplifying unit and source, and particular circuit configurations as shown in Figure 3, Figure 4.
Wherein, Fig. 3 is the schematic diagram of the finger print information testing circuit based on charge injection mode while finger print information not detected, Fig. 4 is the schematic diagram of the finger print information testing circuit based on charge injection mode while finger print information being detected, and the difference of Fig. 3 and Fig. 4 is only that change has occurred feedback unit when finger print information being detected.
In Fig. 3, Fig. 4,201 is reset unit, and 2011 is the first phase inverter, and 2012 is the second phase inverter, and 2013 is the 3rd phase inverter, and 2014 is a N channel metal-oxide-semiconductor field effect transistor; 202 is feedback unit, and 2021 is the first electric capacity, and 2022 is the second electric capacity, and 2013 is the 3rd electric capacity; 103 is amplifying unit, 1031 is a P channel metal-oxide-semiconductor field effect transistor, 1032 is the 2nd P channel metal-oxide-semiconductor field effect transistor, 1033 is the 3rd N channel metal-oxide-semiconductor field effect transistor, and 1034 is the 4th N channel metal-oxide-semiconductor field effect transistor; 105 for following unit in source, and 1051 is source follower, and 1052 is switch.
In Fig. 4,2024 is the 4th electric capacity, and 2025 is the 5th electric capacity, and 2026 is the 6th electric capacity, and 2027 is resistance.
First, introduce the concrete structure of reset unit.Reset unit, except comprising reset transistor, also comprises the first phase inverter, the second phase inverter, the 3rd phase inverter and a N channel metal-oxide-semiconductor field effect transistor.
The input end of the first phase inverter is the input end of reset unit, and output terminal is connected with the input end of the second phase inverter; The output terminal of the second phase inverter is connected with the input end of the 3rd phase inverter; The output terminal of the 3rd phase inverter is connected with the grid of a N channel metal-oxide-semiconductor field effect transistor; The source electrode of the one N channel metal-oxide-semiconductor field effect transistor is connected with drain electrode, wherein, drains as the first output port of reset unit; The first port of reset transistor is connected with the first output port of reset unit, the second output port that the second port is reset unit, and the 3rd port is connected with the output terminal of the second phase inverter.
Wherein, reset transistor is the 2nd N channel metal-oxide-semiconductor field effect transistor; The source electrode of the 2nd N channel metal-oxide-semiconductor field effect transistor is the first port of described reset transistor; The drain electrode of the 2nd N channel metal-oxide-semiconductor field effect transistor is the second port of reset transistor; The grid of the 2nd N channel metal-oxide-semiconductor field effect transistor is the 3rd port of described reset transistor.
And the channel width of reset transistor is the twice of the channel width of a N channel metal-oxide-semiconductor field effect transistor.
According to above-mentioned connection, when input reset signal, reset transistor generation clock feed-through effect and the quantity of electric charge producing because of clock feedthrough are
Q
clk1＝V
clk1W
1C
ov，
Wherein, V
clk1for the clock voltage of reset transistor, W
1for the channel width of reset transistor, C
ovoverlap capacitance for unit width.
Meanwhile, a N channel metal-oxide-semiconductor field effect transistor absorbs the electric charge that reset transistor produces because of clock feedthrough.The one N channel metal-oxide-semiconductor field effect transistor because of the quantity of electric charge that clock feedthrough absorbs is
Q
clk2＝V
clk22W
2C
ov，
Wherein, V
clk2be the clock voltage of a N channel metal-oxide-semiconductor field effect transistor, V
clk2v
clk1through the 3rd phase inverter, obtain the two single spin-echo, i.e. V
clk2=-V
clk1.W
2be the channel width of a N channel metal-oxide-semiconductor field effect transistor, C
ovoverlap capacitance for unit width.
Because the channel width of reset transistor is the twice of the channel width of a N channel metal-oxide-semiconductor field effect transistor, i.e. W
1=2W
2so,,
Q
clk1+Q
clk2=0，
The electric charge that to be reset transistor produce because of clock feedthrough is all absorbed because of clock feedthrough by a N channel metal-oxide-semiconductor field effect transistor, made to eliminate the electric charge that reset transistor produces because of clock feedthrough, make to inject the electric charge that the electric charge of feedback unit all stores from reset transistor, purifying be injected into the charge source of feedback unit.
It is worth mentioning that, reset transistor produces clock feed-through effect when cut-off, meanwhile, produces iunjected charge effect when conducting.In the prior art, both all bring adverse effect to circuit, and in the present embodiment, the electric charge that iunjected charge effect is produced is used, and makes it injection amplification unit and feedback unit.For purifying is injected into the electric charge of amplifying unit and feedback unit, the electric charge because of clock feedthrough generation all sponges by reset transistor to utilize a N channel metal-oxide-semiconductor field effect transistor, like this, not only reduced and set up the design flow that input block produces separately electric charge, reduce the area that finger print information testing circuit based on charge injection mode takies chip, also eliminated the adverse effect that electric charge that clock feedthrough produces brings.
It should be noted that, reset transistor forms a capacity plate antenna when conducting, and the total amount of electric charge of storage is
Q
1＝W
1L
eff1C
OX(V
DD-V
i1-V
t1)，
Wherein, W
1for the channel width of reset transistor, L
eff1for effective channel width of reset transistor, C
oXfor the gate oxide thickness of reset transistor, V
dDbe the first operating voltage, V
i1be the direct current incoming level that the 4th N channel metal-oxide-semiconductor field effect transistor is set up, V
t1on state threshold voltage for reset transistor.
Reset transistor is in when cut-off, the charge Q that reset transistor stores when conducting
1by the first port, the second port, flow out, by source electrode, the drain electrode of the 2nd N channel metal-oxide-semiconductor field effect transistor, flow out, the quantity of electric charge that flow out on every road accounts for 1/2nd of total amount of electric charge.Meanwhile, N channel metal-oxide-semiconductor field effect transistor conducting, absorbs the part iunjected charge that reset transistor produces, and the quantity of electric charge of absorption is
Q
2＝W
2L
eff2C
OX(V
DD-V
i2-V
t2)，
Wherein, W
2be the channel width of a N channel metal-oxide-semiconductor field effect transistor, L
eff2be effective channel width of a N channel metal-oxide-semiconductor field effect transistor, C
oXbe the gate oxide thickness of a N channel metal-oxide-semiconductor field effect transistor, V
dDbe the first operating voltage, V
i2the direct current incoming level that the 4th N channel metal-oxide while ending for reset transistor-semiconductor field effect transistor is set up, V
t2it is the on state threshold voltage of a N channel metal-oxide-semiconductor field effect transistor.
It is worth mentioning that, the first phase inverter, the second phase inverter and the 3rd phase inverter are all for carrying out shaping to the signal receiving.If the time delay of the 3rd phase inverter is shorter or switching time is shorter, the quantity of electric charge that a N channel metal-oxide-semiconductor field effect transistor absorbs is larger; Meanwhile, if the time delay of the second phase inverter is shorter or switching time is shorter, the total amount of electric charge that reset transistor produces is more.
Like this, the quantity of electric charge that the iunjected charge that reset transistor produces is injected into amplifying unit and feedback unit is
Q
3＝Q
1/2-Q
2，
That is to say, be injected into the electric charge of amplifying unit and feedback unit all from the iunjected charge of reset transistor generation, charge source is pure.
Then, introduce the concrete structure of feedback unit.In the present embodiment, feedback unit ground connection.Like this, when finger touch, point entrained static and be conducted to the earth, make to avoid to cause the reset unit, amplifying unit, the source that are connected with feedback unit to follow unit by electrostatic breakdown because pointing entrained static.
When finger print information not detected, as shown in Figure 3, feedback unit comprises the first electric capacity, the second electric capacity and the 3rd electric capacity to the schematic diagram of the finger print information testing circuit based on charge injection mode.
The positive pole of the first electric capacity is connected with the first port of feedback unit, and negative pole is connected with the second port of feedback unit; Wherein, the first port of feedback unit is connected with the first output port of reset unit, and the second port of feedback unit is connected with the second output port of reset unit; The positive pole of the second electric capacity is connected with the first port of feedback unit, minus earth; The positive pole of the 3rd electric capacity is connected with the second port of described feedback unit, minus earth.
Wherein, the external polar plate that the first electric capacity is feedback unit and the coupling capacitance between internal polar plate, the second electric capacity is the coupling capacitance between external polar plate and ground ring, the 3rd electric capacity is the coupling capacitance between internal polar plate and ground ring.The structure of internal polar plate, external polar plate and ground ring can design as required, and as shown in Figure 5, the second structure vertical view is for as shown in Figure 6 for the first structure vertical view that internal polar plate, external polar plate and ground encircle.Present embodiment is preferably selected the structure of the represented internal polar plate of Fig. 5, external polar plate and ground ring, like this, can be so that feedback unit be sensitiveer to the distance of the pole plate of the first built-in electric capacity of feedback unit to fingerprint lines, electrostatic protection better effects if.
In Fig. 5, Fig. 6,501 is internal polar plate, and 502 is external polar plate, and 503 encircle with being.
While finger print information being detected, as shown in Figure 4, feedback unit also comprises the 4th electric capacity, the 5th electric capacity, the 6th electric capacity and resistance to the finger print information testing circuit based on charge injection mode.
In Fig. 4, the positive pole of the 4th electric capacity is connected with the first port of feedback unit, and negative pole is connected with the positive pole of the 5th electric capacity; The negative pole of the 5th electric capacity is connected with the second port of feedback unit; The positive pole of the 6th electric capacity is connected with the negative pole of the 4th electric capacity, the minus earth of the 6th electric capacity; Resistance one end is connected with the positive pole of the 5th electric capacity, other end ground connection.
Wherein, the coupling capacitance between the external polar plate that the 4th electric capacity is feedback unit and finger, the 5th electric capacity is the coupling capacitance between internal polar plate and finger, the coupling capacitance between the 6th electric capacity encircles with being and points, resistance is the resistance between human body and ground ring.
When feedback unit detects finger print information, the capacitance of the first electric capacity of feedback unit changes, thereby the voltage signal that the first electric capacity produces changes, when finger print information not detected tertiary voltage signal become second voltage signal, second voltage signal carries the finger print information detecting.
In the present embodiment, the first electric capacity and fingerprint become non-linear to the distance of feedback unit, make feedback unit can accurately reflect that because the second voltage signal of finger print information generation being detected fingerprint is to the distance of feedback unit, finally make the first voltage signal of fingerprint detection circuit output can reflect more accurately that fingerprint is to the distance of feedback unit.
Then, introduce the concrete structure of amplifying unit.As shown in Figure 3, Figure 4, amplifying unit comprises: a P channel metal-oxide-semiconductor field effect transistor, the 2nd P channel metal-oxide-semiconductor field effect transistor, the 3rd N channel metal-oxide-semiconductor field effect transistor and the 4th N channel metal-oxide-semiconductor field effect transistor.
In Fig. 3, Fig. 4, the grid of the one P channel metal-oxide-semiconductor field effect transistor is the first port of amplifying unit, be used for inputting the first bias voltage, source electrode is the second port of amplifying unit, be used for inputting the first operating voltage, drain electrode is connected with the source electrode of the 2nd P channel metal-oxide-semiconductor field effect transistor; The grid of the 2nd P channel metal-oxide-semiconductor field effect transistor is the 3rd port of amplifying unit, be used for inputting the second bias voltage, drain electrode is the 4th port of amplifying unit, and is connected with the drain electrode of the 3rd N channel metal-oxide-semiconductor field effect transistor; The grid of the 3rd N channel metal-oxide-semiconductor field effect transistor is the five-port of described amplifying unit, and for inputting the 3rd bias voltage, source electrode is connected with the drain electrode of the 4th N channel metal-oxide-semiconductor field effect transistor; The grid of the 4th N channel metal-oxide-semiconductor field effect transistor is the 6th port of amplifying unit, is connected with the first output port of reset unit, and source ground.
Amplifying unit amplifies rear output to the received signal.Because amplifying unit is existing proven technique, do not repeat them here.
Finally, introduce the concrete structure of source follower.Source is followed unit and is comprised source follower and switch; Source follower is connected with switch.
Wherein, source follower is the 5th N channel metal-oxide-semiconductor field effect transistor; Switch is the 6th N channel metal-oxide-semiconductor field effect transistor; The drain electrode of the 5th N channel metal-oxide-semiconductor field effect transistor is the first port that unit is followed in described source, be used for inputting the second operating voltage, grid is the second port that unit is followed in source, be connected with the 4th port of amplifying unit, source electrode is connected with the drain electrode of the 6th N channel metal-oxide-semiconductor field effect transistor; The grid of the 6th N channel metal-oxide-semiconductor field effect transistor is the 3rd port of described source follower, for input switch signal, source electrode is the 4th port of source follower, and for exporting the first voltage signal, the first voltage signal carries the finger print information of detection.
Source is followed unit the signal receiving is carried out exporting the first voltage signal after level translation.Due to source, following unit is existing proven technique, does not repeat them here.
So far, the concrete structure introduction of the finger print information testing circuit based on charge injection mode finishes.
It is worth mentioning that the first electric capacity that iunjected charge, feedback unit are built-in and the relation between finger print information.Be specifically described as follows:
The quantity of electric charge that reset transistor is injected into amplifying unit and feedback unit is respectively Q
4, Q
5so, have
Q
3＝Q
4+Q
5,
And the electric charge that is injected into amplifying unit is the electric charge that is injected into the 4th N channel metal-oxide-semiconductor field effect transistor actually, so
Q
4＝C
in1ΔV
in1，
Wherein, C
in1be the capacitance of the 4th N channel metal-oxide-semiconductor field effect transistor, Δ V
in1for the input voltage variable quantity producing because of charge injection, and
C
in1＝W
3L
eff3C
OX,
Wherein, W
3be the channel width of the 4th N channel metal-oxide-semiconductor field effect transistor, L
eff3be effective channel width of the 4th N channel metal-oxide-semiconductor field effect transistor, C
oXfor gate oxide thickness.
In like manner, the electric charge that is injected into feedback unit is actually the electric charge that is injected into the first electric capacity, so,
Q
5＝C
1ΔV
2,
Wherein, C
1be the capacitance of the first electric capacity, Δ V
2for the voltage variety producing at the first electric capacity two ends because of charge injection.
Meanwhile, because of
ΔV
2＝ΔV
O1-ΔV
in1，
ΔV
O1＝A
v0ΔV
in1，
Wherein, Δ V
o1for Δ V
in1output voltage variable quantity after amplifying unit amplifies.
Through simplifying, process, and in conjunction with A
v0the condition of > > 1, can obtain
Herein, Δ V
o1identical with second voltage signal, then, Δ V
o1through source, follow unit and carry out the first voltage signal that level translation obtains output, carry the voltage signal of finger print information.
From above formula, the variation of the capacitance of the first electric capacity determines the variation of the first voltage signal of output, and the change of the first capacitance is determined by the finger print information detecting, so, the first voltage signal of the finger print information final decision output detecting, the first voltage signal carries the voltage signal of finger print information.Wherein, the lines that finger print information comprises fingerprint is to the distance of the pole plate of the first electric capacity.That is to say, in the situation that the first electric capacity stores electric charge, while finger print information being detected, the capacitance of the first electric capacity changes, thereby causes the change of the first voltage signal of output, therefore the first voltage signal carries the finger print information detecting.
Persons of ordinary skill in the art may appreciate that the respective embodiments described above are to realize specific embodiment of the utility model, and in actual applications, can to it, do various changes in the form and details, and do not depart from spirit and scope of the present utility model.
Claims (10)
1. the finger print information testing circuit based on charge injection mode, comprises amplifying unit and unit is followed in source; Described amplifying unit is followed unit with described source and is connected; Described amplifying unit exports described source to after the signal of reception is amplified and follows unit; Described source is followed unit the signal receiving is carried out exporting the first voltage signal after level translation, and wherein, described the first voltage signal carries the finger print information of detection; It is characterized in that, also comprise reset unit, feedback unit;
Wherein, described feedback unit exports the second voltage signal of generation to described source and follows unit when finger print information being detected;
Described reset unit is all connected with described feedback unit, described amplifying unit; Described feedback unit is connected with described amplifying unit; The input end of described reset unit is used for inputting reset signal;
When described reset signal is high level, reset transistor conducting stored charge that described reset unit is built-in reset to described feedback unit simultaneously; When described reset signal switches to low level by high level, the cut-off of described reset transistor, and by the charge injection of storage to described feedback unit and described amplifying unit;
Described feedback unit receives described electric charge, and when finger print information being detected, exports described second voltage signal to described source and follow unit.
2. the finger print information testing circuit based on charge injection mode according to claim 1, it is characterized in that, described reset unit comprises the first phase inverter, the second phase inverter, the 3rd phase inverter and a N channel metal-oxide-semiconductor field effect transistor;
The input end of described the first phase inverter is the input end of described reset unit, and output terminal is connected with the input end of described the second phase inverter;
The output terminal of described the second phase inverter is connected with the input end of described the 3rd phase inverter;
The output terminal of described the 3rd phase inverter is connected with the grid of a described N channel metal-oxide-semiconductor field effect transistor;
The source electrode of a described N channel metal-oxide-semiconductor field effect transistor is connected with drain electrode, wherein, and the first output port that described drain electrode is described reset unit;
The first port of described reset transistor is connected with the first output port of described reset unit, the second output port that the second port is described reset unit, and the 3rd port is connected with the output terminal of described the second phase inverter.
3. the finger print information testing circuit based on charge injection mode according to claim 2, is characterized in that, described reset transistor is described the 2nd N channel metal-oxide-semiconductor field effect transistor;
Wherein, the first port that the source electrode of described the 2nd N channel metal-oxide-semiconductor field effect transistor is described reset transistor; The drain electrode of described the 2nd N channel metal-oxide-semiconductor field effect transistor is the second port of described reset transistor; The grid of described the 2nd N channel metal-oxide-semiconductor field effect transistor is the 3rd port of described reset transistor.
4. the finger print information testing circuit based on charge injection mode according to claim 3, is characterized in that, the channel width of described reset transistor is the twice of the channel width of a described N channel metal-oxide-semiconductor field effect transistor.
5. the finger print information testing circuit based on charge injection mode according to claim 2, is characterized in that, described feedback unit ground connection.
6. the finger print information testing circuit based on charge injection mode according to claim 5, is characterized in that, described feedback unit comprises the first electric capacity, the second electric capacity and the 3rd electric capacity;
The positive pole of described the first electric capacity is connected with the first port of described feedback unit, and negative pole is connected with the second port of described feedback unit;
Wherein, the first port of described feedback unit is connected with the first output port of described reset unit, and the second port of described feedback unit is connected with the second output port of described reset unit;
The positive pole of described the second electric capacity is connected with the first port of described feedback unit, minus earth;
The positive pole of described the 3rd electric capacity is connected with the second port of described feedback unit, minus earth.
7. the finger print information testing circuit based on charge injection mode according to claim 6, is characterized in that, described feedback unit also comprises the 4th electric capacity, the 5th electric capacity, the 6th electric capacity and resistance;
The positive pole of described the 4th electric capacity is connected with the first port of described feedback unit, and negative pole is connected with the positive pole of described the 5th electric capacity;
The negative pole of described the 5th electric capacity is connected with the second port of described feedback unit;
The positive pole of described the 6th electric capacity is connected with the negative pole of described the 4th electric capacity, the minus earth of described the 6th electric capacity;
Described resistance one end is connected with the positive pole of described the 5th electric capacity, other end ground connection.
8. the finger print information testing circuit based on charge injection mode according to claim 1, it is characterized in that, described amplifying unit comprises a P channel metal-oxide-semiconductor field effect transistor, the 2nd P channel metal-oxide-semiconductor field effect transistor, the 3rd N channel metal-oxide-semiconductor field effect transistor and the 4th N channel metal-oxide-semiconductor field effect transistor;
The grid of a described P channel metal-oxide-semiconductor field effect transistor is the first port of described amplifying unit, be used for inputting the first bias voltage, source electrode is the second port of described amplifying unit, be used for inputting the first operating voltage, drain electrode is connected with the source electrode of described the 2nd P channel metal-oxide-semiconductor field effect transistor;
The grid of described the 2nd P channel metal-oxide-semiconductor field effect transistor is the 3rd port of described amplifying unit, be used for inputting the second bias voltage, drain electrode is the 4th port of described amplifying unit, and is connected with the drain electrode of described the 3rd N channel metal-oxide-semiconductor field effect transistor;
The grid of described the 3rd N channel metal-oxide-semiconductor field effect transistor is the five-port of described amplifying unit, and for inputting the 3rd bias voltage, source electrode is connected with the drain electrode of described the 4th N channel metal-oxide-semiconductor field effect transistor;
The grid of described the 4th N channel metal-oxide-semiconductor field effect transistor is the 6th port of described amplifying unit, is connected with the first output port of described reset unit, and source ground.
9. the finger print information testing circuit based on charge injection mode according to claim 8, is characterized in that, described source is followed unit and comprised source follower and switch;
Described source follower is connected with described switch.
10. the finger print information testing circuit based on charge injection mode according to claim 9, is characterized in that, described source follower is the 5th N channel metal-oxide-semiconductor field effect transistor;
Described switch is the 6th N channel metal-oxide-semiconductor field effect transistor;
Wherein, the drain electrode of described the 5th N channel metal-oxide-semiconductor field effect transistor is the first port that unit is followed in described source, be used for inputting the second operating voltage, grid is the second port that unit is followed in described source, be connected with the 4th port of described amplifying unit, source electrode is connected with the drain electrode of described the 6th N channel metal-oxide-semiconductor field effect transistor;
The grid of described the 6th N channel metal-oxide-semiconductor field effect transistor is the 3rd port of described source follower, and for input switch signal, the 4th port that source electrode is described source follower, for exporting described the first voltage signal.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201420074718.0U CN203812253U (en) | 2014-02-20 | 2014-02-20 | A fingerprint information detection circuit based on an electric charge injection mode |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201420074718.0U CN203812253U (en) | 2014-02-20 | 2014-02-20 | A fingerprint information detection circuit based on an electric charge injection mode |
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| Publication Number | Publication Date |
|---|---|
| CN203812253U true CN203812253U (en) | 2014-09-03 |
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|---|---|---|---|
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Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN104866803A (en) * | 2014-02-20 | 2015-08-26 | 上海思立微电子科技有限公司 | Fingerprint information detection circuit |
| CN105488451A (en) * | 2014-09-26 | 2016-04-13 | 上海思立微电子科技有限公司 | Fingerprint recognition sensor |
| CN105512714A (en) * | 2014-09-26 | 2016-04-20 | 上海思立微电子科技有限公司 | Fingerprint identification sensor and sensing area thereof |
-
2014
- 2014-02-20 CN CN201420074718.0U patent/CN203812253U/en not_active Expired - Lifetime
Cited By (9)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN104866803A (en) * | 2014-02-20 | 2015-08-26 | 上海思立微电子科技有限公司 | Fingerprint information detection circuit |
| WO2015123921A1 (en) * | 2014-02-20 | 2015-08-27 | 上海思立微电子科技有限公司 | Fingerprint information detection circuit |
| US9542587B2 (en) | 2014-02-20 | 2017-01-10 | Silead, Inc. | Fingerprint information detection circuit |
| US9922230B2 (en) | 2014-02-20 | 2018-03-20 | Silead, Inc. | Fingerprint information detection circuit |
| CN104866803B (en) * | 2014-02-20 | 2018-06-05 | 上海思立微电子科技有限公司 | A kind of finger print information detection circuit |
| CN105488451A (en) * | 2014-09-26 | 2016-04-13 | 上海思立微电子科技有限公司 | Fingerprint recognition sensor |
| CN105512714A (en) * | 2014-09-26 | 2016-04-20 | 上海思立微电子科技有限公司 | Fingerprint identification sensor and sensing area thereof |
| CN105512714B (en) * | 2014-09-26 | 2019-02-15 | 上海思立微电子科技有限公司 | A kind of fingerprint Identification sensor and its induction region |
| CN105488451B (en) * | 2014-09-26 | 2019-07-12 | 上海思立微电子科技有限公司 | A kind of fingerprint Identification sensor |
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