modified 7 years ago

LTP-based Schmitt trigger

00:41:48

Just wanted to try this. It goes high at 3.45V, low at 1.83V. Capable of about 500kHz.

published 7 years ago

jason9

7 years ago

Add one more inverting stage to the output and hook that up to the input and it goes at just over 1MHz.

eekee

7 years ago

hook what up to the input?

jason9

7 years ago

Add one more inverting stage to the output and hook the output of that second inverting stage to the input.

eekee

7 years ago

That's strange, that would be negative feedback. I don't want to bother adding all that for a x2 gain, but I've got another idea now.

eekee

7 years ago

@jason9: 3MHz: http://everycircuit.com/circuit/5955120608313344

jason9

7 years ago

I know it’s negative feedback, but because it’s a Schmitt trigger there is no stable point. When the output is high it crosses the upper threshold causing the output to go low causing it to cross the lower threshold causing the output to go high again, the speed only limited by the design.

eekee

7 years ago

Oh right, you mean to make an oscilator out of it. Yeah, that works. It reminds me of the last time I tried to make an op-amp. I put in several amplification stages, so it amplified well, but had a high propagation delay. When I gave it negative feedback, it oscilated! It was stable with positive feedback, so I called it a comparator.

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