Triangular and sinusoidal signal generator project

Thread Starter

Iulia Baginean

Joined Apr 22, 2017
Hi! I need a little help with my school project.
I have to simulate in Pspice a triangular and sinusoidal signal generator with adjustable frequency and amplitude. I tought about using an astable multivibrator to generate a rectangular signal, which output goes into an integrator circuit to obtain a triangular waveform and after integrating this one I should get a sinusoidal wave.
The problem is that after simulating I don't get any of the waveforms I want. I tried to simulate each part. From the astable multivibrator I get a trapezoidal signal instead of a rectangular.
Can you help me a little bit? Maybe it's the idea bad from the begining


Joined Jun 4, 2014
The '741 is old and has very limited rise time and gain bandwidth product. Either try a much lower frequency or a faster opamp.


Joined Aug 1, 2013
First, you can't get a 10 kHz squarewave out of a 741. It does not have sufficient gain-bandwidth. Of course, your simulation program might not know this, depending on the quality of it's 741 model.
Second, unless the components are perfectly matched, the integrator will not make a perfect triangle wave because its timing has to be exactly the same as the square wave. If its time constant is a bit smaller, the triangle wave will be clipped. If its timing is a bit larger, the triangle will diminish to zero.

Search the web for function generator circuits, and you will see many examples of making the first opamp a comparator. Its output still will be a squarewave, but it will self-align to the timing parameters of the integrator for a constant integrator output amplitude regardless of frequency.