Jung precision clipper - smoothing transient spikes?

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I want to get rid of the transient spikes in this clipper circuit from Jung's opamp cookbook.

I know I can reduce the value of R4 - e.g. taking it to 1K gets rid of them completely - but it also significantly increases the current draw across R4 when the circuit is not clipping.

The input signals will be AC and within the audio range.

Is there a way to get rid of - or at least reduce - the spikes without a big increase in current draw across R4?

Thanks.

 

[KlausST]

Hi,

* use a high speed OPAMP
* high frequency diode (low capacitance)
* limit OPAMP U2 output voltage during "clip" to avoid overdrive of OPAMP input stage. Read about OPAMP "phase reversal", "latch up" and "input overdrive recovery"

In your circuit, the OPAMP outut voltage usually is 0.55V below V+ inut voltage. But when the limiter is active the OPAMP output voltage (marked wit "2") immediately rises to positive supply rail. Maybe coupling from output to V- input causes the spikes.

The spikes could be because of
* traces capacitive coupling
* diode capacitance
* diode reverse recovery (time, charge)

Consider a low pass filter at the output

Also take care that the signal you see is really the signal of the limiter, and not effects of the scope´s jig.

Good luck

Klaus