TW201600850A - Frequency-shift readout circuit - Google Patents

Abstract

A frequency-shift readout circuit includes a biosensor, a power detector, a voltage detector, a register and a subtractor. The biosensor receives a frequency sweep signal and outputs a detected signal. The power detector receives the detected signal and outputs a voltage signal, wherein the amplitude of the voltage signal is associated with the amplitude of the detected signal. The voltage detector receives the voltage signal to detect the peak or valley value of the voltage signal and outputs a trigger signal. The register receives the frequency signal and the trigger signal, and the register retrieves the resonant frequency of the frequency sweep signal according to the trigger signal, and the register provides a reference frequency signal and a resonant frequency signal to the subtractor, and the subtractor computes a frequency diversity between the reference frequency signal and the resonant frequency signal.

Description

Frequency shift read circuit

This invention relates to a frequency shift read circuit, and more particularly to a frequency shift read circuit having a wide input frequency range.

Referring to FIG. 1 , a conventional frequency shift reading circuit 200 has a biomedical sensor 210 , a low pass filter 220 and a peak detector 230 . The biomedical sensor 210 receives a sweep signal. Freq_sweep and output a sense signal out _sensor , the low pass filter receives the sense signal out _sensor and outputs a filtered signal out _1pf , the peak detector receives the filtered signal out _1pf to detect the filtered signal out _1pf The frequency shift value of the frequency sweep signal freq_sweep is obtained by the peak value, but the sense signal out _sensor outputted by the biomedical sensor 210 is filtered by the low pass filter 220 to generate an attenuation, which is originally sensed by the biomedical sensor. The amplitude change of the sensing signal out _sensor outputted by the device 210 is extremely small, and furthermore, it is more difficult to detect after the attenuation, and the reading of the peak detector 230 at the back end is difficult. Therefore, the conventional frequency shift reading is performed. The frequency to which the circuit 200 can be applied is rather limited and cannot be widely used.

The main purpose of the present invention is to detect the power of the detection signal output by the biomedical sensor by using a power detector with high input bandwidth and high conversion gain, and then detect the power detection by the voltage detector. The peak value or valley value of the voltage signal outputted by the detector obtains the time position of the peak or valley value, and the frequency difference of the frequency sweep signal is obtained by the register and the subtractor of the back end. Since the power detector has a high input bandwidth and a high conversion gain, the read range of the frequency shift reading circuit can be effectively improved, and the complexity of the back end circuit can be reduced to accelerate the operation time required to capture the center frequency.

A frequency shift reading circuit of the present invention comprises a biomedical sensor, a power detector, a voltage detector, a register and a subtractor, and the biomedical sensor receives a sweep signal, and the The biomedical sensor outputs a detection signal, the power detector receives the detection signal, and the power detector outputs a voltage signal, wherein the amplitude of the voltage signal is related to the amplitude of the detection signal, the voltage The detector receives the voltage signal, the voltage detector is configured to detect the peak value or the bottom value of the voltage signal, and the voltage detector outputs a trigger signal, and the register receives the trigger signal and the frequency sweep signal. The register receives the resonant frequency of the frequency sweep signal according to the trigger signal, and the register provides a reference frequency signal and a resonant frequency signal, and the subtractor receives the reference frequency signal and the resonant frequency signal, and the The subtractor calculates a frequency difference between the resonant frequency signal and the reference frequency signal.

The power detector detects the detection signal output by the biomedical sensor, and the power detector has high input bandwidth, so it can be applied to various medical sensing of various bandwidths. In addition, because the power detector has a high conversion gain, the amplitude change of the detection signal output by the biomedical sensor can be more easily detected, and the voltage detector of the back end can be accelerated. The detection speed is finally obtained by the buffer of the back end and the subtractor to obtain the frequency difference of the frequency sweep signal to measure the characteristics of the object to be tested.

Referring to FIG. 2, FIG. 3, FIG. 4 and FIG. 5, a frequency shift reading circuit 100 includes a frequency sweep signal generator A, a biomedical sensor 110, and a power detector 120. A voltage detector 130, a register 140 and a subtractor 150.

Referring to FIGS. 2 and 3, the sweep signal generator A outputs a sweep signal freq_sweep, the biomedical sensor 110 receives the sweep signal freq_sweep, and the biomedical sensor 110 outputs a detection signal V _rf1 Referring to FIG. 4, in the embodiment, the biomedical sensor 110 is a tape-rejecting biomedical sensor, and the spectrum analysis characteristic is a rejection type, such as a film bulk acoustic wave sensor (Film). Bulk Acoustic Resonator (FBAR), the closer the frequency of the frequency sweep signal freq_sweep received by the biomedical sensor 110 is to the resonance frequency, the lower the amplitude of the detection signal V _rf1 output by the biomedical sensor 110 . The equivalent circuit of the biomedical sensor 110 has a first resistor 111a, a first inductor 112a and a first capacitor 113a, wherein one end of the first resistor 111a receives the sweep signal freq_sweep, the first resistor 111a the other end is connected a first node n1, the first ends of the inductor 112a are connected to the first capacitor 113a and the first node n1, the other end 113a of the first capacitor, that the detection signal V _rf1 The voltage of the first node n1.

Referring to FIGS. 2 and 3, the power detector 120 receives the detection signal V _rf1 , and the power detector 120 outputs a voltage signal V _out , and the amplitude of the voltage signal V _out and the detection signal For the amplitude correlation, please refer to FIG. 5. In this embodiment, the power detector 120 has a DC blocking capacitor 121, an AC blocking inductor 122, a bias circuit 123, and a first transistor 124 and a first A load resistor 125, one end of the DC blocking capacitor 121 receives the detection signal V _rf1 , and the other end of the DC blocking capacitor 121 is connected to a second node n2 to filter out the DC component of the detection signal V _rf1 . The two ends of the AC blocking inductor 122 are respectively connected to the second node n2 and the bias circuit 123. The bias circuit 123 provides a stable bias voltage V _{rf_bias} . Preferably, the bias circuit 123 is a bandgap circuit (bandgap circuit), in order to avoid temperature effects of the magnitude of the bias voltage _V rf_bias, the first transistor gate terminal 124 of the second node n2 is connected to a first terminal of the electrical brake crystal 124 via the AC blocking inductor The bias voltage V _{rf —} bias is received by 122 to bias the first transistor 124 to the saturation region, and the AC blocking inductor 122 filters out the AC component of the bias voltage V _{rf —} bias . The first terminal of the first transistor 124 is connected to a voltage terminal VCC. The source of the first transistor 124 is grounded. The voltage signal V _{out is} the voltage of the first terminal of the first transistor 124. . In this embodiment, the first transistor 124 is an N-type MOS field effect transistor. When the amplitude of the detection signal V _rf1 is smaller, the level of the voltage signal V _out is higher. Therefore, when the biomedical sensor 110 detects the resonant frequency, the amplitude of the detection signal V _rf1 is the smallest, and the voltage signal V _{out has} the highest level, and is detected by the voltage detector 130 at the back end. The peak value of the voltage signal V _out can detect the resonance frequency time point of the frequency sweep signal freq_sweep.

Referring to FIGS. 2 and 3, the voltage detector 130 receives the voltage signal V _out , the voltage detector 130 is configured to detect the peak value of the voltage signal V _out , and the voltage detector 130 outputs a trigger signal. Trigger. Referring to FIG. 6, in the embodiment, the voltage detector 130 has a first operational amplifier 131a, a first switching transistor 132a, a first charging capacitor 133a, a high-torque inverter 134a, and a first first reset transistor 135a, 131a of the first operational amplifier having a first ne1 negative terminal, a first positive terminal and a first output terminal po1 op1, the first negative terminal ne1 receiving the voltage signal V _out, the The first output terminal op1 is connected to the high-torque inverter 134a and the gate terminal of the first switching transistor 132a. The first positive electrode po1 is connected to the first terminal of the first switching transistor 132a and the first charging capacitor 133a. The one of the first charging capacitors 133a is connected to the first charging capacitor 133a. The first resetting transistor 135a is connected to the first charging capacitor 133a. The first resetting transistor 135a is used to connect the first charging capacitor 135a. The potential of the first charging capacitor 133a is lowered to a low level to prevent the potential of the first charging capacitor 133a from being unknown when the circuit is activated.

Referring to FIG. 6 , the circuit of the voltage detector 130 is activated. When the voltage signal V _out continues to rise, the voltage signal V _{out is} greater than an output received by the first positive terminal po1 of the first operational amplifier 131a. The voltage out _opa , at this time, an operation voltage vopa outputted by the first output terminal op1 of the first operational amplifier 131a is low, and the trigger signal trigger output by the high-torque inverter 134a is high, and The first switching transistor 132a is a P-type MOS field effect transistor. Therefore, when the operating voltage received by the gate terminal of the first switching transistor 132a is low, the first switching transistor 132a is turned on and the first switching transistor 132a is turned on. A charging capacitor 133a is charged to increase the potential of the first charging capacitor 133a, so that the output voltage out _opa rises, and when the voltage signal V _out stops rising or falling, the output voltage out _{opa is} greater than the voltage signal V _out , Therefore, the operating voltage vopa rises to a high potential, the trigger signal trigger outputted by the high-torque inverter 134a is low, and the first switching transistor 132a is turned off to stop toward the first charging 133a charge, this time is the peak of the voltage signal V _out, thereby actuating the circuit can be learned, Ruoyu obtained peak signal voltage V _out of the generation time, the falling edge of the last fetch trigger signal trigger a trigger The time (from high potential to low potential) is sufficient.

Please refer to FIGS. 7 and 8 respectively, which are circuit diagrams of the first operational amplifier 131a and the high torsional inverter 134a of the voltage detector 130, wherein the high-torque inverter 134a is a general CMOS inverter. The high-torque inverter 134a is formed by a PMOS having a larger W/L ratio (channel width/channel length) and an NMOS having a smaller W/L ratio, thereby preventing the voltage signal V _out and the output voltage out _opa The potential is unstable during the value-added process, and unnecessary noise is filtered by the high-torque inverter 134a.

Referring to FIG. 2, the register 140 receives the trigger signal trigger and the sweep signal freq_sweep, and the buffer 140 captures the sweep signal freq_sweep according to the time point of the trigger of the trigger signal trigger. a resonant frequency, and the frequency shift reading circuit 100 captures a resonant frequency of the sweep signal freq_sweep without any object to be tested and a resonant frequency of the sweep signal freq_sweep of the object to be tested, A reference frequency signal and a resonant frequency signal are respectively provided by the register 140. Finally, the subtractor 150 receives the reference frequency signal and the resonant frequency signal, and the subtractor 150 calculates the resonant frequency signal and the reference frequency. A frequency difference between the signals, which is analyzed to obtain the characteristics of the test object.

Referring to Figures 2, 3, 4, 9 and 10, a second embodiment of the present invention is different from the first embodiment in that the power detector 120 further has a second transistor 126 and a second The load resistor 127 and a double-turn single operational amplifier 128 are shown in FIG. 9. The gate terminal of the second transistor 126 is connected to the bias circuit 123 and the AC blocking inductor 122. The second transistor 126 is at the extreme end. The voltage terminal VCC is connected via the second load resistor 127, the source of the second transistor 126 is grounded, and the second transistor 126 receives the bias voltage V _{rf_bias of} the bias circuit 123 to make the second power The crystal 126 is biased in the saturation region, and the AC blocking inductor 122 prevents the detection signal V _{rf1 from being} coupled to the second transistor 126 to affect the signal output by the second transistor 126. The dual-transistor operational amplifier 128 has a first input terminal 128a, a second input terminal 128b, and a voltage output terminal 128c. The first input terminal 128a is connected to the second terminal of the second transistor 126. The second input terminal is connected to the second input terminal 128a. 128b connected to the drain terminal of the first transistor 124, the voltage output terminal 128c which outputs the voltage signal V _out. In this embodiment, since the first transistor 124 and the second transistor 126 have the same size, the resistance values of the first load resistor 125 and the second load resistor 127 are also the same, and therefore, by the first transistors 124 and 126 outputs the second electrical signal to obtain the crystals of the voltage signal V _out, avoid the output of the power detector 120 when the voltage signal V _out by the change in the DC bias voltage, process, temperature and supply voltage Impact. However, since the signal of the 输出 extreme output of the second transistor 126 is a fixed DC level, when the biomedical sensor 110 detects the resonant frequency, the amplitude of the detection signal V _rf1 is the smallest, and the pair the output 128 of the operational amplifier to single voltage amplitude signal V _out will be minimized, in the present embodiment, the rear end of the voltage detector 130 detects the valley of the signal voltage V _out of the sweep to detect give The resonant frequency time point of the signal freq_sweep.

Referring to FIG. 10, in the embodiment, the voltage detector 130 has a second operational amplifier 131b, a second switching transistor 132b, a second charging capacitor 133b, a low torsion inverter 134b, and a first a second reset transistor 135b, the second operational amplifier having a second negative terminal 131b ne2, a second positive terminal and a second output terminal po2 op2, the second negative terminal ne2 receiving the voltage signal V _out, the The second output terminal op2 is connected to the gate terminal of the low-turning reverser 134b and the second switching transistor 132b. The second positive terminal po2 is connected to the second terminal of the second switching transistor 132b and the second charging capacitor 133b. And one end of the second charging capacitor 133b is connected to the voltage terminal VCC, the low torsion inverter 134b outputs the trigger signal, and the second reset transistor 135b is connected to the second charging capacitor 133b, the second reset transistor 135b is used to charge the potential of the second charging capacitor 133b to a high potential to prevent the potential of the second charging capacitor 133b from being unknown when the circuit is activated.

See FIG. 10, the voltage detector circuit 130 is actuated when the output is a voltage signal V _out continued to decline, the voltage signal V _out is smaller than the second po2 positive terminal of the second operational amplifier 131b received The voltage out _opa , at this time, an operation voltage vopa outputted by the second output terminal op2 of the second operational amplifier 131b is high, and the trigger signal trigger output by the low-torque inverter 134b is low, and The second switching transistor 132b is an N-type MOS field effect transistor. Therefore, when the operating voltage vopa received by the gate terminal of the second switching transistor 132b is at a high potential, the second switching transistor 132b is turned on to enable the second switching transistor 132b to be turned on. The second charging capacitor 133b is discharged, so that the potential of the second charging capacitor 133b is lowered, so that the output voltage out _opa also decreases, and when the voltage signal V _out stops falling or rising, the output voltage out _{opa is} smaller than the voltage signal V. _Out , therefore, the operating voltage vopa drops to a low potential, the trigger signal trigger outputted by the low-torque inverter 134b is high, the second switching transistor 132b is turned off and the second charging capacitor 133b stop the discharge, is the case when the voltage signal V _out of the valley, thereby actuating the circuit can be learned, Ruoyu obtained when the voltage signal generating valley V _out of time, to retrieve the last of the trigger signal trigger The time for the positive edge trigger (from low to high) is sufficient.

Please refer to FIGS. 7 and 8 respectively, which are circuit diagrams of the second operational amplifier 131b and the low torsional inverter 134b of the voltage detector 130, wherein the low torsion inverter 134b is a general CMOS inverter. By configuring the low-torsion inverter 134b with a PMOS having a smaller W/L ratio (channel width/channel length) and having a larger W/L ratio, the voltage signal V _out and the output voltage out _{opa can be} prevented. The potential is unstable during the value recovery process, and unnecessary noise is filtered by the low twist reverser 134b.

Referring to FIG. 2, in the embodiment, the buffer 140 receives the trigger signal and the frequency sweep signal, and the buffer 140 is triggered according to the last positive edge of the trigger signal trigger. Taking the resonant frequency of the sweep signal freq_sweep, and the frequency shift reading circuit 100 respectively captures the resonant frequency of the sweep signal freq_sweep without any object to be tested and adds a scan of the object to be tested. The resonant frequency of the frequency signal freq_sweep, and a reference frequency signal and a resonant frequency signal are respectively provided by the register 140. Finally, the subtractor 150 receives the reference frequency signal and the resonant frequency signal, and the subtractor 150 calculates the frequency. A frequency difference between the resonant frequency signal and the reference frequency signal, and the frequency difference is analyzed to obtain characteristics of the measured object.

Please refer to Figures 2, 11, 12, 13 and 14 for a third embodiment of the present invention, which differs from the first embodiment in that the biomedical sensor 110 is a band-pass biomedical sensor. The characteristic of the spectrum analysis is a bandpass type, such as a Flexural Plate Wave (FPW). The frequency of the sweep signal freq_sweep received by the biomedical sensor 110 is closer to the resonance frequency. The amplitude of the detection signal V _rf1 output by the medical sensor 110 is higher. Referring to FIG. 12, the equivalent circuit of the biomedical sensor 110 has a second resistor 111b, a second inductor 112b and a second capacitor 113b. The one end of the second inductor 112b receives the sweep signal freq_sweep. The two ends of the second capacitor 113b are respectively connected to the second inductor 112b and a third node n3. The two ends of the second resistor 111b are respectively connected to the third node n3 and the ground. The detection signal V _{rf1 is} the third The voltage of node n3.

Referring to FIG. 13 , in the embodiment, the power detector 120 receives the detection signal V _rf1 and outputs the voltage signal V _out from the first terminal of the first transistor 124, because in this embodiment. The closer the frequency of the sweep signal freq_sweep received by the biomedical sensor 110 is to the resonance frequency, the higher the amplitude of the detection signal V _rf1 output by the biomedical sensor 110 is, so that the power detector is The lower the amplitude of the voltage signal V _out outputted by the 120, therefore, referring to FIG. 14, in the embodiment, the voltage detector 130 at the rear end adopts the same architecture as the second embodiment, and the voltage is the same. The detector 130 detects the time at which the voltage signal V _{out is} outputted by the power detector 120. The circuit of the voltage detector 130 is the same as that of the second embodiment, and details are not described herein. Referring to FIG. 2 , the register 140 receives the trigger signal trigger, and captures the resonant frequency of the sweep signal freq_sweep at the last positive edge trigger time of the trigger signal trigger, and the frequency shift reading circuit 100 By taking one without adding any test object The resonant frequency of the frequency sweeping signal freq_sweep and the resonant frequency of the swept frequency signal freq_sweep of the object to be tested are respectively provided by the register 140 to provide a reference frequency signal and a resonant frequency signal. Finally, the subtractor 150 The reference frequency signal and the resonant frequency signal are received, and the subtractor 150 calculates a frequency difference between the resonant frequency signal and the reference frequency signal, and the frequency difference is analyzed to obtain the characteristics of the measured object.

Referring to Figures 2, 11, 12, 15 and 16, a fourth embodiment of the present invention differs from the first embodiment in that the biomedical sensor 110 is constructed in the same manner as the third embodiment. The power detector 120 is configured in the same manner as the second embodiment. Referring to FIG. 12, the biomedical sensor 110 receives the sweep signal freq_sweep, and the scan is received by the biomedical sensor 110. The closer the frequency of the frequency signal freq_sweep is to the resonance frequency, the higher the amplitude of the detection signal V _rf1 output by the biomedical sensor 110 is.

Then, referring to FIG. 15 , the voltage detector 130 receives the detection signal. In this embodiment, when the frequency of the frequency sweep signal freq_sweep is closer to the resonance frequency, the amplitude of the detection signal V _rf1 is higher. The smaller the amplitude of the signal of the 汲 extreme output of the first transistor 124, and the signal of the 输出 extreme output of the second transistor 126 is a fixed DC level, when the biomedical sensor 110 reaches the resonant frequency. The amplitude of the detection signal V _rf1 is the largest, and the amplitude of the voltage signal V _out outputted by the dual-single operational amplifier 128 is the largest. In this embodiment, the voltage detector 130 at the back end is the same as the first embodiment. The voltage detector 130 has the same structure and is used to detect the peak value of the voltage signal V _out to detect the resonance frequency time point of the frequency sweep signal freq_sweep.

Referring to FIG. 16 , in the embodiment, the voltage detector 130 detects a time point at which the voltage signal V _{out is} outputted by the power detector 120, and the circuit of the voltage detector 130 is activated. The same as the first embodiment, and the details are not described herein again. Referring to FIG. 2, the register 140 receives the trigger signal trigger, and captures the frequency sweep signal by the last negative edge trigger time point of the trigger signal trigger. a resonance frequency of the freq_sweep, and the frequency shift reading circuit 100 respectively obtains a resonance frequency of the frequency sweep signal freq_sweep without any object to be tested and a resonance of the frequency sweep signal freq_sweep of the object to be tested a reference frequency signal and a resonant frequency signal are respectively provided by the register 140. Finally, the subtractor 150 receives the reference frequency signal and the resonant frequency signal, and the subtractor 150 calculates the resonant frequency signal and the Referring to a frequency difference between the frequency signals, the frequency difference is analyzed to obtain the characteristics of the test object.

The power detector 120 detects the detection signal V _rf1 output by the biomedical sensor 110, and the power detector 120 has a high input bandwidth, so it can be applied to multiple bandwidths. The biosensor sensor furthermore, because the power detector 120 has a high conversion gain, the amplitude change of the detection signal V _rf1 output by the biomedical sensor 110 can be more easily detected, which can be accelerated. The detection speed of the voltage detector 130 at the back end is finally obtained by the register 140 and the subtractor 150 of the back end to obtain the frequency difference of the frequency sweeping signal freq_sweep to measure the object to be tested. characteristic.

The scope of the present invention is defined by the scope of the appended claims, and any changes and modifications made by those skilled in the art without departing from the spirit and scope of the invention are within the scope of the present invention. .

100‧‧‧frequency shift reading circuit
110‧‧‧ biomedical sensor
111a‧‧‧First resistance
112a‧‧‧first inductance
113a‧‧‧first capacitor
111b‧‧‧second resistance
112b‧‧‧second inductance
113b‧‧‧second capacitor
120‧‧‧Power Detector
121‧‧‧DC blocking capacitor
122‧‧‧AC blocking inductor
123‧‧‧Bias circuit
124‧‧‧First transistor
125‧‧‧First load resistor
126‧‧‧second transistor
127‧‧‧second load resistor
128‧‧‧Double-turn single operational amplifier
128a‧‧‧ first input
128b‧‧‧ second input
128c‧‧‧voltage output
130‧‧‧Voltage Detector
131a‧‧‧First operational amplifier
132a‧‧‧First switch transistor
133a‧‧‧First charging capacitor
134a‧‧‧High Torsion Inverter
135a‧‧‧First reset transistor
131b‧‧‧Second operational amplifier
132b‧‧‧Second switch transistor
133b‧‧‧second charging capacitor
134b‧‧‧Low torsion reverser
135b‧‧‧Second reset transistor
140‧‧‧ register
150‧‧‧Subtractor
N1‧‧‧ first node
N2‧‧‧ second node
N3‧‧‧ third node
VCC‧‧‧ voltage terminal
Po1‧‧‧first positive end
Ne1‧‧‧first negative end
Op1‧‧‧first output
Po2‧‧‧second positive end
Ne2‧‧‧second negative end
Op2‧‧‧second output
A‧‧‧sweep signal generator
Freq_sweep‧‧‧Sense signal
Rst‧‧‧Reset signal
V _rf1 ‧‧‧detection signal
V _out ‧‧‧voltage signal
Out _sensor ‧‧‧Sense signal
V _{rf_bias ‧‧‧bias}
Trigger‧‧‧trigger signal
Out _opa ‧‧‧output voltage
Out _{1pf ‧‧‧Filter} signal
Peak‧‧‧peak signal
Vopa‧‧‧Operating voltage
200‧‧‧frequency shift reading circuit
210‧‧‧ biomedical sensor
220‧‧‧low pass filter
230‧‧‧ Peak Detector

Figure 1: A block diagram of a frequency shift read circuit of the prior art. 2 is a block diagram of a frequency shift read circuit in accordance with an embodiment of the present invention. 3 is a block diagram of a biomedical sensor, a power detector, and a voltage detector in accordance with an embodiment of the present invention. Figure 4: An equivalent circuit diagram of the biomedical sensor in accordance with an embodiment of the present invention. Figure 5 is a circuit diagram of the power detector in accordance with a first embodiment of the present invention. Figure 6 is a circuit diagram of the voltage detector in accordance with a first embodiment of the present invention. Figure 7 is a circuit diagram of a first operational amplifier in accordance with an embodiment of the present invention. Figure 8 is a circuit diagram of a high torsional inverter and a low torsion inverter in accordance with an embodiment of the present invention. Figure 9 is a circuit diagram of the power detector in accordance with a second embodiment of the present invention. Figure 10 is a circuit diagram of the voltage detector in accordance with a second embodiment of the present invention. 11 is a block diagram of a biomedical sensor, a power detector, and a voltage detector in accordance with an embodiment of the present invention. Figure 12 is an equivalent circuit diagram of the biomedical sensor in accordance with an embodiment of the present invention. Figure 13 is a circuit diagram of the power detector in accordance with a third embodiment of the present invention. Figure 14 is a circuit diagram of the voltage detector in accordance with a third embodiment of the present invention. Figure 15 is a circuit diagram of the power detector in accordance with a fourth embodiment of the present invention. Figure 16 is a circuit diagram of the voltage detector in accordance with a fourth embodiment of the present invention.

100‧‧‧frequency shift reading circuit

110‧‧‧ biomedical sensor

120‧‧‧Power Detector

130‧‧‧Voltage Detector

140‧‧‧ register

150‧‧‧Subtractor

A‧‧‧sweep signal generator

Claims (21)

A frequency shift reading circuit includes: a biomedical sensor that receives a sweep signal, and the biomedical sensor outputs a detection signal; a power detector receives the detection signal, and the power detection The detector outputs a voltage signal, wherein the amplitude of the voltage signal is related to the amplitude of the detection signal; a voltage detector receives the voltage signal, and the voltage detector is configured to detect a peak or a valley of the voltage signal, And the voltage detector outputs a trigger signal; a register receives the trigger signal and the frequency sweep signal, and the buffer acquires a resonant frequency of the frequency sweep signal according to the trigger signal, and the register provides the a reference frequency signal and a resonant frequency signal; and a subtractor receiving the reference frequency signal and the resonant frequency signal, and the subtractor calculates a frequency difference between the resonant frequency signal and the reference frequency signal. The frequency shift reading circuit of claim 1, wherein the biomedical sensor is a strip type biomedical sensor. The frequency shift reading circuit of claim 2, wherein the power detector has a DC blocking capacitor, an AC blocking inductor, a bias circuit, a first transistor, and a first load resistor. One end of the DC blocking capacitor receives the detection signal, and the other end of the DC blocking capacitor is connected to a second node, and the two ends of the AC blocking inductor are respectively connected to the second node and the bias circuit, the first transistor The gate of the first transistor is connected to the second node. The first terminal of the first transistor is connected to a voltage terminal via the first load resistor. The source of the first transistor is grounded. The voltage signal is the terminal of the first transistor. The voltage. The frequency shift reading circuit of claim 3, wherein the first transistor is an N-type metal oxide half field effect transistor. The frequency shift reading circuit of claim 3, wherein the voltage detector has a first operational amplifier, a first switching transistor, a first charging capacitor, and a high twisting inverter. An operational amplifier has a first negative terminal, a first positive terminal and a first output terminal. The first negative terminal receives the voltage signal, and the first output terminal is connected to the high-torque inverter and the first switching device. The first positive terminal is connected to the first terminal of the first switching transistor and the first charging capacitor, and one end of the first charging capacitor is grounded, and the high-torque inverter outputs the trigger signal. The frequency shift reading circuit of claim 5, wherein the first switching transistor is a P-type gold oxide half field effect transistor. The frequency shift reading circuit of claim 5, wherein the voltage detector has a first reset transistor, the first reset transistor is connected to the first charging capacitor, and the first reset power The crystal is used to lower the potential of the first charging capacitor to a low potential. The frequency shift reading circuit of claim 3, wherein the power detector has a second transistor, a second load resistor and a double-turn single operational amplifier, and the gate terminal of the second transistor is connected. The bias circuit and the alternating current blocking inductor, the second terminal of the second transistor is connected to the voltage terminal via the second load resistor, the source of the second transistor is grounded, and the double-turn single operational amplifier has a first An input end, a second input end and a voltage output end, wherein the first input end is connected to the 汲 terminal of the second transistor, the second input end is connected to the 汲 terminal of the first transistor, and the voltage output end outputs the Voltage signal. The frequency shift reading circuit of claim 8, wherein the voltage detector has a second operational amplifier, a second switching transistor, a second charging capacitor, and a low torsional inverter. The second operational amplifier has a second negative terminal, a second positive terminal and a second output terminal. The second negative terminal receives the voltage signal, and the second output terminal is connected to the low torsion inverter and the second switch. a gate terminal of the crystal, the second positive terminal is connected to a drain terminal of the second switch transistor and the second charging capacitor, and one end of the second charging capacitor is connected to the voltage terminal, and the low twist reverser outputs the trigger signal . The frequency shift reading circuit of claim 9, wherein the second switching transistor is an N-type metal oxide half field effect transistor. The frequency shift reading circuit of claim 9, wherein the voltage detector has a second reset transistor, the second reset transistor is connected to the second charging capacitor, and the second reset power The crystal is used to charge the potential of the second charging capacitor to a high potential. The frequency shift reading circuit of claim 1, wherein the biomedical sensor is a band pass biomedical sensor. The frequency shift reading circuit of claim 12, wherein the power detector has a DC blocking capacitor, an AC blocking inductor, a bias circuit, a first transistor, and a first load resistor. One end of the DC blocking capacitor receives the detection signal, and the other end of the DC blocking capacitor is connected to a second node, and the two ends of the AC blocking inductor are respectively connected to the second node and the bias circuit, the first transistor The gate of the first transistor is connected to the second node. The first terminal of the first transistor is connected to a voltage terminal via the first load resistor. The source of the first transistor is grounded. The voltage signal is the terminal of the first transistor. The voltage. The frequency shift reading circuit of claim 13, wherein the first transistor is an N-type gold oxide half field effect transistor. The frequency shift reading circuit of claim 13, wherein the voltage detector has a second operational amplifier, a second switching transistor, a second charging capacitor, and a low torsional inverter. The second operational amplifier has a second negative terminal, a second positive terminal and a second output terminal. The second negative terminal receives the voltage signal, and the second output terminal is connected to the low torsion inverter and the second switch. a gate terminal of the crystal, the second positive terminal is connected to a drain terminal of the second switch transistor and the second charging capacitor, and one end of the second charging capacitor is connected to the voltage terminal, and the low twist reverser outputs the trigger signal . The frequency shift reading circuit of claim 14, wherein the second switching transistor is an N-type metal oxide half field effect transistor. The frequency shift reading circuit of claim 15, wherein the voltage detector has a second reset transistor, the second reset transistor is connected to the second charging capacitor, and the second reset power The crystal is used to charge the potential of the second charging capacitor to a high potential. The frequency shift reading circuit of claim 13, wherein the power detector has a second transistor, a second load resistor and a double-turn single operational amplifier, and the gate terminal of the second transistor is connected. The bias circuit and the alternating current blocking inductor, the second terminal of the second transistor is connected to the voltage terminal via the second load resistor, the source of the second transistor is grounded, and the double-turn single operational amplifier has a first An input end, a second input end and a voltage output end, wherein the first input end is connected to the 汲 terminal of the second transistor, the second input end is connected to the 汲 terminal of the first transistor, and the voltage output end outputs the Voltage signal. The frequency shift reading circuit of claim 18, wherein the voltage detector has a first operational amplifier, a first switching transistor, a first charging capacitor, and a high twisting inverter. An operational amplifier has a first negative terminal, a first positive terminal and a first output terminal. The first negative terminal receives the voltage signal, and the first output terminal is connected to the high-torque inverter and the first switching device. The first positive terminal is connected to the first terminal of the first switching transistor and the first charging capacitor, and one end of the first charging capacitor is grounded, and the high-torque inverter outputs the trigger signal. The frequency shift reading circuit of claim 19, wherein the first switching transistor is a P-type gold oxide half field effect transistor. The frequency shift reading circuit of claim 19, wherein the voltage detector has a first reset transistor, the first reset transistor is connected to the first charging capacitor, and the first reset power The crystal is used to lower the potential of the first charging capacitor to a low potential.