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LPF and Schmitt trigger alternative design for IC

imrankhanPNU

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Hello
I am recovering the PWM message signal at the demodulator side of the system. In the attached schematics you can see Low pass filter which filters high frequency, then the signal is fed to Schmitt trigger to retrieve the message signal. I aimed to design the whole system on IC 350nm technology, in which it's preferred to use small size and fewer components. I would like to know:

1) Is there any alternative for LPF, which perform the same job, with a small and fewer component? Especially I am concerned about dealing with a large resistor while implementing LPF on the IC chip.

2) Second, Is there any best alternative to my Schmitt trigger design, with fewer components?

Thanks in advance.
 

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dick_freebird

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Think about digital approaches to chatter suppression.
This might be called "debounce".

RC filter may attenuate signal "noise" but often the
bounce / chatter on slow moving signals is self-
induced through ground loops, which the RC won't
help and might hurt (cap to ground, is a high pass filter
for ground noise to reach the input).
 

BradtheRad

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I'm thinking of a zener diode (about 1.2V) acting as a clamp eliminating the upper peaks of the jagged waveform (your red scope trace).
Or, 2 plain diodes pointing downward have the same effect. They should add up to 1.2 volts which appears to be about right.
 

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