Precision Rectifier

Experiment 6

Aim:

To study the Half Wave and Full Wave Rectifier and to obtain the required graph.

Apparatus Required:

Theory:

An inverting Op-Amp can be converted into a half wave rectifier by adding two diodes. When Vi is positive, diode D1 conducts causing Vo to go to positive by one diode drop. Hence diode D2 is reverse biased. The output voltage Vo is zero because for all practical purposes no current flows through D1 for –ve input, D2 conducts and D1 is OFF. The – ve input Vi forces the Op-Amp output Vo –ve and causes D2 to conduct. The circuit then acts like inverter for Rf = R1 and the output Vo becomes positive. The Op-Amp in the circuit must be high Op-Amp since it alternates between open loop and closed loop operations. The principal limitation of this circuit is the slew rate of the Op-Amp. As the input passes through zero the Op-Amp output Vo must change from 0.6 to -0.6v or vice versa as quickly as possible in order to switch over the conduction from one diode to another.

Circuit Diagram

Observations

Procedure

1. Connections are made as per the circuit diagram

2. A sinusoidal signal from audio oscillator is applied to the inverting terminal of op-amp

3. The rectified output is then obtained on the CRO

Link to experiment

Go here and select Experiment 6

Demonstration Video