Clipping Diode Question

[mgrEIGHT]

when using two types of diodes in series for clipping does it matter the order (ge then silicon then ground or silicon then ge then ground) what about in opamp feedback loops?

[Khas Evets]

This a good question I've been meaning to ask as well.

Obviously with diodes in series, you add the forward voltage thresholds together and the order doesn't affect that. But how does this affect the knee? As I understand it, knee is a function of current over a voltage curve. So with two diodes as voltage rises, when you meet the threshold of the first diode no current will flow since its blocked by the second diode. The question is when the second diode's forward voltage is met will the knee for both diodes start at that point, or will only the second diode's knee come into play?

[mgrEIGHT]

also what about parallel diodes?

[Khas Evets]

With parallel diodes, the one with the lowest threshold becomes becomes effectively a closed circuit, and the other one never reaches it's threshold.