SU1388977A1 - Voltage-to-current converter - Google Patents

Abstract

The invention relates to radio engineering and m. used in integrated semiconductor circuitry. The purpose of the invention is to increase the linearity of conversion into current by Bbixodf Bm81 iLje. The converter contains three amplifying elements (CI) 1-3, having one type of structure, and CI 4-6, having another type of structure, g-ry 7 and 8 current. Led 9, 10 current, resistor (P) 11, and UE 1-6 are implemented on field-effect transistors. The voltage on P 11 completely repeats the difference of the input voltage, since P-- the device is linear, then the difference in the output current of the converter will depend linearly on the difference in the input voltage, and the equivalent slope of the converter will be equal to the resistance value P 11. 1 Il. and B6fxffd2 (L L- 8xed2 00 00 00; o |

Description

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This invention relates to radio engineering and can be used in integrated semiconductor circuitry.

The purpose of the invention is to increase the linearity of the voltage-to-current conversion.

The drawing shows an electrical circuit diagram of a voltage-to-current converter.

The voltage to current converter contains the first 1, second 2, third 3, fourth A, fifth 5 and sixth 6 amplifying elements made on field-effect transistors, first 7, second 8, third 9 and fourth 10; current generators, resistor 11 ; Voltage to current converter

I works as follows.

I When the input voltage I 8xa from zero, through the siren-- I torus II current flows, For this reason, through the field transistors 1-6 I voltage-to-current converter various currents and their difference flow; between the gate and the source | Qi, -Ci1 C, and} -isi4e is different from | zero. Using Kirchhoff's laws, it is possible to write down the equations relating the potentials of the shells of the nodes:

U ,, Ke-U.,:;

Thu + and, and, -i, TsC, + and, "3 ,,, -и, Ш,„

(one

Voltage to current depends on the input voltage difference linearly, and the equivalent slope of the voltage to current converter is equal to the value of the resistor P. Condition (2) is satisfied when, in the above converter circuit, the topological dimensions of the field transistors and the currents of the current generators satisfy the following conditions;

K, S,

T T T t

 2 2g 2

(3)

0

five

where K; - the specific steepness of the 1st on the left transistor; S; - the ratio of the width to the channel length of the i-ro transistor; 1 | - current value of i-ro. current generator.

At the same time, the difference in the output current U Igjj, is connected with the difference in the input voltage by the linear relation

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R

1.b, .iv,

(four)

The validity of expression (4) is easy to check if you substitute into the system (Voltages expressed through their drain currents. Accepting;, the quadratic dependence of the drain current 1 of the field-effect transistor on the voltage between the gate and the source

where and, „; - voltage between the gate and the source of the 1st field-effect transistor; and - voltage on the resistor P. to

The third equation in system (1) is m; it can be rewritten as

 , - (and, „, - and,„ J + (u ,,, u ,,,).

(2)

A linear voltage-to-current converter is obtained when the condition and,) is fulfilled. The physical meaning of this condition is that, if the displacement monitor voltage difference is the error signal of the voltage converter Ei current, then the voltage across the resistor 11 will completely repeat the difference of the input voltage AUg. And since the resistor is a linear device, the difference in output current is 1 kB {and, „- and

where K is the specific slope;

S is the ratio of the channel width to

channel length;

and - threshold voltage. we get that

We substitute this expression at the extreme point of the dynamic range of the voltage to current converter, i.e. when the current through the second field-effect transistor 2 is zero, and the current through the first field-effect transistor 1 is equal to twice the value of its modal current, it. In this case, we obtain (see system (1))

2loI 21, + 2lo (2I ,, llo-lo ,,,.

K7. "

217+ Ilo-Io 12 V2I ,, - llo-Io. „. /five)

icTsrNl KTs; i-kjs; -, -

u "MK, S,

As can be seen from the system (5), & Ug under the condition

(3) Thus, the voltage across the resistor 11 repeats the input voltage, and the dynamic range of the converter is t | 21o / / K, S ,. A similar verification of the validity of the system (PI and Eq. (4), under condition (3), can be carried out at any point within the dynamic range of the device. The result is the same.

Thus, the proposed voltage-to-current converter has a high accuracy of linear conversion voltage to current.

Claims (1)

Claims of Invention A voltage to current converter comprising first and second amplifying elements having one type of structure and third, fourth, fifth, and sixth amplifying elements having a different type of structure, and the control inputs of the first and second amplifying elements are first and second inputs of the voltage to current converter, the output of the first amplifying element is connected to the outputs of the third and sixth The amplifying element is connected to the outputs of the fourth and fifth amplifying elements, the antiphase outputs of the first and second amplifying elements are respectively the first and second outputs of the voltage to current converter, the control input of the third amplifying element is connected to its antiphase output, with a control input n that usi- 50 Compiled by N. Dubro. Editor E. Kopcha Tehred M. Khodanych the first element of the current generator, the control input of the fourth amplifying element is connected to its anti-phase output, the control input of the sixth amplifying element and the first output of the second current generator, the second terminals of the current generator are connected to the corresponding power supply bus, characterized in that , in order to increase the linearity of the voltage-to-current conversion, a resistor and the third and fourth current generators are introduced, and the amplifying elements are made on field-effect transistors, and The currents of the transistors of the fifth and sixth amplifying elements are connected to the first terminals of the second and first current generators, respectively, and the first and second terminals of the resistor; the first terminals of the third and fourth current generators are connected to the sources of the transistors of the first and second amplifiers, respectively; current is connected to the corresponding power supply bus, while the topological dimensions of the transistors and the mode currents of the current generators satisfy the following ootnosheni m: 1, -1, K, S, -K, jS, -K, 2r - 3T, - K. is the specific slope of the i-ro transistor; S is the ratio of the channel width to channel length i-ro transis-. Torah; I; current value of i-ro current generator. Proofreader A.T. sko