Electrical Engineering ⇒ Topic : Voltage to Current Converter
Voltage to Current Converter
Figure (a) shows the schematic diagram for converting the voltage to current in which load resistance RL is floating, i.e., neither side grounded. In this case, the circuit provides a current proportional to the voltage signal.
figure (a) Voltage to current converter
The voltage gain Aν, is very large for OP Amp, Vi = O. Therefore, it can be written as:
VS = Vf = R1IL
Equation (1) represents the load current /L through the load resistor RL at output. The input Vs in this case is converted into an output current Vs/R1. So it can be said that the input Vs appears across R1. The output current IL = Vs/R1 can be fixed precisely when R1 is a precision resistor.
If the load RL is grounded, the circuit shown in Figure (a) should not be used. The schematic diagram in this case is shown in Figure (b) where one side of load resistance RL is grounded
Figure (b) Voltage to current converter.
Applying KCL at node x,
I1 + I2 = IL
From Eq. (2), the load current depends on the input voltage VS, and resistor R. The load resistance should be less than or equal to R for satisfactory operation.
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