# Electronics - Operational Amplifiers - Discussion

Discussion Forum : Operational Amplifiers - General Questions (Q.No. 4)

4.

What is the output waveform?

Discussion:

47 comments Page 1 of 5.
Karuppasamy kpk said:
1 decade ago

If the input voltage is zero, no input current will flow. Therefore no feedback current can flow and the output voltage will remain constant. If the input voltage is non-zero, the basic equation for the output voltage becomes Vout = -Vin/RC + K, where R is the input resistance in ohms, C is the feedback capacitance in farads, and K is a fixed constant representing the accumulated voltage from the past.

If the input voltage is constantly changing, the output voltage at any instant will be the integral of all past input voltage values. For example, a bipolar sine wave input will actually produce another sine wave as its output, at a phase angle of 90° from the input sine wave. Technically, the output will be an inverted cosine wave.

If the input is a constant positive dc voltage, the output will be a negative linear ramp. There is no exponential factor in an op amp integrator. The equation for the ramp will be Vout = -Vint/RC, where t is time in seconds.

If the input voltage is constantly changing, the output voltage at any instant will be the integral of all past input voltage values. For example, a bipolar sine wave input will actually produce another sine wave as its output, at a phase angle of 90° from the input sine wave. Technically, the output will be an inverted cosine wave.

If the input is a constant positive dc voltage, the output will be a negative linear ramp. There is no exponential factor in an op amp integrator. The equation for the ramp will be Vout = -Vint/RC, where t is time in seconds.

Ramyy said:
9 years ago

If we think logically, we have capacitor in feedback so capacitor here initially charge when supply is given and than it discharge so we get two types of wave either saw tooth and triangular but here capacitor discharge slowly. So answer is triangular waves.

Santosh Kumar sahu said:
6 years ago

It's not possible to find output. Without any input wave form. But to my point of view, according to answer if the input is a square wave. Then only the output will be a triangular wave. Otherwise not possible to find the output waveform.

Karuppasamy kpk said:
1 decade ago

So according to given above statement, input must be need to desire the output of the integrator

when sine input --------> co(sine) output

when dc input-------> ramp output(squar wave---> triangular wave)

when sine input --------> co(sine) output

when dc input-------> ramp output(squar wave---> triangular wave)

GIRISH KUMAR N G said:
7 years ago

It's an integrator where capacitor charges and discharges which produce a sawtooth waveform. Then the sawtooth waveform is given to the comparator which gives a square waveform. So it's not a triangular waveform.

Ahmed khan said:
10 years ago

When I/P is unit step then O/P is ramp signal. When I/P is Square wave then O/P is triangular wave. Because circuit is integrator But in this question we do not have given then answer will be Data insufficient.

Vanshika Agarwal said:
6 months ago

Until the input waveform is not specified we cannot guess the output waveform.

The integrator also behaves like a waveform converter :

sine - cos

step - ramp

ramp - parabolic and

square - triangular wave.

The integrator also behaves like a waveform converter :

sine - cos

step - ramp

ramp - parabolic and

square - triangular wave.

Sanjay kumar said:
6 years ago

Input is not cleared then how are you say that output is triangular?

When the input is rectangular wave then the output is a trangular wave.

When the input is rectangular wave then the output is a trangular wave.

Sanjay kumar said:
6 years ago

Input is not cleared then how are you say that output is triangular?

When the input is rectangular wave then the output is a trangular wave.

When the input is rectangular wave then the output is a trangular wave.

(1)

Kumar rahul said:
9 years ago

Input should be square wave then integration of square wave (can be represented by unit step) gives ramp function i.e triangular.

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