Table of Contents
Voltage Follower, Voltage to Current Converter with floating loads (V/I), Voltage to current Converter with Grounded load
In the Non-inverting Amplifier Configuration, if R1= ∞ and Rf=0. The Amplifier functions as a voltage Follower or Unity-gain Amplifier.
The circuit consist of an op-amp and a wire connecting the output voltage to the input ,i.e the output voltage is equal to the input voltage, both in magnitude and phase.V0=Vi
The circuit is known as a voltage follower because its output voltage follows its input voltage. It provides very low output impedance and extremely high input impedance of the order of M. As a result, this circuit uses very little source current. So For impedance matching applications, the voltage follower can be used as a buffer between a high impedance source and a low impedance load.
1. Voltage to Current Converter with floating loads (V/I)
1. Voltage to current converter in which load resistor RL is floating (not connected to ground).
2. So Vin is applied to the non inverting input terminal, and the feedback voltage across R1 devices the inverting input terminal.
3. This circuit is also called as a current – series negative feedback amplifier.
4. Because the feedback voltage across R1 (applied Non-inverting terminal) depends on the output current i0 and is in series with the input difference voltage Vid
So From the fig input voltage Vin is converted into output current of Vin/R1 [Vin ->i0 ] . In other words, input volt appears across R1. So If R1 is a precision resistor, the output current (i0 = Vin/R1 ) will be precisely fixed.
Voltage follower Applications:
1. Low voltage ac and dc voltmeters
2. Diode match finders
4. Zener diode testers.
2. Voltage to current Converter with Grounded load
This is the other type V – I converter, in which one terminal of the load is connected to ground.
Analysis of the circuit:
The analysis of the circuit can be done by following 2 steps.
1. To determine the voltage V1 at the non-inverting (+) terminals and
2. To establish relationship between V1 and the load current IL .
So Applying KCL at node V1 we can write that,