SU945810A1 - Device for converting voltage to current - Google Patents

Description

one

The invention relates to electrical measuring equipment, in particular, the conversion of voltage to current, and can be used in parametric control equipment for digital integrated circuits.

Voltage-to-current devices are known, comprising two operational amplifiers, a resistive voltage divider and a series-connected transistor, a current sensor and a load, the junction point of which is connected to the zero potential bus, a resistive divider connected between the non-inverting input of the first operational amplifier and the emitter of the transistor and its middle output is connected to the inverting input of the second operational amplifier, the output of which is connected to the non-inverting input of the first operating voltage silica gel. The first VHSD device is connected to the inverting input of the first

operational amplifier, and the second with non-inverting input of the second operational amplifier Cl}.

The disadvantage of this device is the low accuracy of voltage-to-current conversion due to different values of the conversion coefficients of the two input signals, since the current flowing through the re, Q is a sistive voltage divider, is part of the output current of the converter.

The purpose of the invention is to improve the accuracy of pre () development.

, 5 The goal is achieved by the fact that in a device for npeot Span voltage in that containing two operational amplifiers, a resistive voltage divider,

Claims (2)

20 one of the extreme terminals of which is connected to the output of the second operational amplifier, and the middle output to the inverting input of this operational amplifier, is a sequential but switched on transistor, the base of which is connected to the output of the first operational amplifier, current sensor and load, the connection point of which is connected to the zero potential bus , the emitter of the transistor is connected to the non-inverting input of the second operational amplifier, the output of which is connected to the inverting input of the first operational amplifier connected non-inverting vhrdom to the first input of the device, the second vhrd of which is connected to the other extreme output of the resistive voltage divider. The drawing shows a diagram of the proposed device. The device contains the first 4 and 2 operational amplifiers, a resistive voltage divider 3, made of two series-connected resistors and 5, and a transistor 6 connected in series, a current sensor 7 and a load 8. Non-inverting input the first operational amplifier 1 is connected to the first input 9 of the device, and the inverting input to the output of the second operational amplifier 2. Resistive voltage divider 3 is connected between the second input 10 of the device and the output of the second operational amplifier 2, and its middle output is connected to the inverting input of this amplifier, the non-inverting input of which is connected to the emitter of transistor 6, the output of the first operational amplifier 1 is connected to the base of transistor 6 whose collector is connected to the power bus 11. The operation of the device is as follows. When voltage Ug is applied to the first and second inputs of the device) (and current sensor 7 produces a voltage, the value of which is determined from the expression T-VIR BX "L R. 4. + R5. The output current of the device flows through the collector-emitter circuit of the transistor 6, - current sensor 7 - load 8. When an output current flows through current sensor 7, a voltage drop is generated at the latter, the value of which is equal to the voltage UT. 4 Therefore, the output current of the device is determined from the expression P v% - RT where K ( V, p is the conversion factor of the input voltage the input voltage U. If the values of the resistances of the resistors and 5 are equal, i.e. RR p, the values of conversion coefficients on the first and second inputs of the device are also equal, i.e. 2. In this case, the expression of the output current of the device will - KtUBxi Uexi), where K is the conversion ratio of the converter. The current of the resistive voltage divider 3 does not flow through the output current circuit and does not affect the accuracy of the conversion of voltage to current. Claim device A device for converting a voltage into a current containing two operational amplifiers, a resistive voltage divider, one of the extreme terminals of which is connected to the output of the second operational amplifier, and an average terminal to the inverting input of this operational amplifier, a series-connected transistor, the base of which is connected to the output of the first operational amplifier, the current sensor and the load, the coupling of which is connected to the zero potential bus, characterized in that, in order to increase the exact of the transformations, the emitter of transistor is connected to the noninverting input of the second operational amplifier of which the output is connected to the inverting input of the first operational amplifier non-inverting input connected to the first input device, the second input of which is connected to the other terminal of extreme resistive voltage divider. Sources of information taken into account in the examination 1. USSR author's certificate GR 706791, cl. G 01 R 19/00, 1978.