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Design >> RF Design >> Why do we have stability issues as the frequency of operation increases?
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Message started by Venky_analog on Jan 27^th, 2016, 11:12am

Title: Why do we have stability issues as the frequency of operation increases?
Post by Venky_analog on Jan 27^th, 2016, 11:12am

I read somewhere that we can have stability issues in basic CMOS open-loop circuits because of parasitic coupling between the input and output. My questions is why does it happen only in high frequency circuits such as RF/mm-Wave circuits?

Is it because when we design the circuit to have high gain at higher frequencies, because of coupling from output to input there is a positive feedback with loop gain > 1?

Title: Re: Why do we have stability issues as the frequency of operation increases?
Post by loose-electron on Jan 27^th, 2016, 11:10pm

The higher the frequency the lower the impedance for the parasitic capacitance.

Not terribly difficult...