## Monday, April 4, 2011

### INTEGRATOR

INTEGRATOR

Obtain the output of an Integrator circuit with component values R1Cf = 0.1ms, Rf = 10 R1 and Cf = 0.01 µF , if 2 V peak to peak square wave at 1000Hz is applied as input.

AIM:

To design an Integrator circuit for the given specifications using Op-Amp IC 741.

APPARATUS REQUIRED:

 S.No Name of the Apparatus Range Quantity 1. Function Generator 3 MHz 1 2. CRO 30 MHz 1 3. Dual RPS 0 – 30 V 1 4. Op-Amp IC 741 1 5. Bread Board 1 6. Resistors 7. Capacitors 8. Connecting wires and probes As required

THEORY:

A circuit in which the output voltage waveform is the integral of the input voltage waveform is the integrator.  Such a circuit is obtained by using a basic inverting amplifier configuration if the feedback resistor Rf  is replaced by a capacitor Cf .  The expression for the output voltage is given as,

Vo = - (1/Rf C1) ∫ Vi dt

Here the negative sign indicates that the output voltage is 180 0 out of phase with the input signal.  Normally between fa and fb the circuit acts as an integrator.  Generally, the value of fa < fb .  The input signal will be integrated properly if the Time period T of the signal is larger than or equal to Rf Cf.  That is,

T ≥ Rf Cf

The integrator is most commonly used in analog computers and ADC and signal-wave shaping circuits.

PIN DIAGRAM:

CIRCUIT DIAGRAM OF INTEGRATOR:

DESIGN:

We know   the frequency at which the gain is 0 dB, fb = 1 / (2π R1 Cf)
Therefore fb = _____
Since fb = 10 fa, and also the gain limiting frequency fa = 1 / (2π Rf Cf)
We get, Rf = _______   and hence R1 = __________

PROCEDURE:

1.  Connections are given as per the circuit diagram.
2. + Vcc and - Vcc supply is given to the power supply terminal of the Op-Amp IC.
3. By adjusting the amplitude and frequency knobs of the function generator, appropriate input voltage is applied to the inverting input terminal of the Op-Amp.
4. The output voltage is obtained in the CRO and the input and output voltage waveforms are plotted in a graph sheet.

OBSERVATIONS:

 S.No. Amplitude( No. of div x Volts per div ) Time period( No. of div x Time per div ) Input Output

MODEL GRAPH:

RESULT:

The design of the Integrator circuit was done and the input and output waveforms were obtained.