Using OP-AMP to convert square wave to triangle wave

Allen Du

Hi Team,

My I ask a question, is there any simple method to convert a square wave to triangle wave.

The square wave lower voltage is 0V, higher voltage is 2V-4V, frequency 50kHz, periodic 20uS.
For example when input square wave is 0-2V, need output is 0-2V triangle wave. and only rising edge is important.

I tried simulate using op-amp integrator but didn't get the expected result. could you help advice, thanks in advance.

over 1 year ago

0 kai klaas69 over 1 year ago

Guru 140200 points

Hi Allen,

you may need to discharge the integrating capacitor by the help of a transistor or analog switch.

Can you show your simulation file?

These threads may interest you:

https://e2e.ti.com/support/amplifiers-group/amplifiers/f/amplifiers-forum/981548/tlv9062-need-assistance-in-a-problem-with-triangle-wave-generator

https://e2e.ti.com/support/amplifiers-group/amplifiers/f/amplifiers-forum/743851/lm741-balancing-signal

Kai

0 Allen Du over 1 year ago in reply to kai klaas69

Prodigy 250 points

Hi Kai,

Thanks for your reply, I am using analog switch to discharge when input is low voltage, please advice will it work, thnaks!

+1 kai klaas69 over 1 year ago in reply to Allen Du

Guru 140200 points

Hi Allen,

the low-to-high edge ("attack") is curved and not linear because U2 is no true integrator. You would need to increase R12 to make the feedback loop look more like an ideal capacitance.

The high-to-low edge ("decay") is not sharp and fast because C1 and R30 form a time constant of about 7µs. You need to decrease this time constant.

I would increase R15 by a factor of ten and decrease C1 also by a factor of ten. And I would increase R12 by a factor of at least twenty. To be able to accomplish this you may need to take a different OPAmp in the integrator section which provides lower input bias currents and accepts higher valued feedback resistors.

Kai