Waveshaper: Amplitude changing as frequency changes

Question

I have designed a Sawtooth to triangular waveshaper using a precision full wave rectifier.I added C1 to stop clipping and the parallel resistors R7 and R5 to get the triangle's ampitude the same as the sawtooth (5V). But as the frequency gets higher, the amplitude is decreasing. Any ideas of how this can be prevented?

UPDATE: This desing is for a music synthesiser, so the input sawtooth will vary from 30Hz to 1Khz while wanting to keep the amplitude about the same. It is also important that the triangle wave has an average offset of 0. So that it can be again converted into a sin wave later

Without Capacitor

Answer 1

I am not quite sure that I can fully understand what you are intending to achieve with your circuit configuration but there are a couple of problems that you need to correct.

1. Get rid of the capacitor C1. The reason you are getting clipping is because you are asking the second opamp to produce an output that is 10V peak and yet the power supply to that opamp is only 9V. Increase the power supply to a higher value like 12V.
2. I believe that you need to be setting up your input saw tooth waveform to be a bipolar signal instead of one that goes from 0 to 5V. (But I may be misunderstanding your design intent so maybe you could describe in your question a bit more how you wanted this circuit to function).