Push pull oscillator

[aj1000]

Hi I have a 5v oscillator taken from 3v3 to 5v using a mosfet push pull circuit. . There is a small pulse on top of each rising edge of each pulse. What causes it and how can I get riid of it?

Thnaks for your help
Al

 

[danadak]

Did you calibrate your scope probes ? Ground lead on probe very short ? Probe
set to X10 (if your scope does not auto detect probe setting) ?

Sears Circuits Lab | Case School of Engineering | Case Western Reserve University

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Probing Tips and Tricks

An oscilloscope probe’s ground connection to a Device Under Test (DUT) is often a significant contributor to measurement error. Here we look at a classic 10x passive probe, its various ground

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Regards, Dana.

 

[rjenkinsgb]

The circuit you show is not really suitable for building with discrete components, or for voltage level translation.

Both FETs will be turned on briefly during each input transition, and with the input only reaching 3.3V the upper FET may be permanently conducting to some extent.
The upper FET will also be receiving a rather higher gate-source voltage when on, which could explain the overshoot?

Some of the pulse on the scope could also be capacitive feedthrough internally to the FETs, plus the dive asymmetry?

(I don't think it's a scope artefact, as they are usually symmetrical & there is no negative overshoot at all).

 

[ZipZapOuch]

Add some decoupling capacitors across your Vdd and ground pins one 0.1uF ceramic and a larger 10uF or bigger electrolytic. Then make sure your probe is set up correctly as suggested above.

 

[ZipZapOuch]

I don't think it's a scope artefact, as they are usually symmetrical & there is no negative overshoot at all

Which makes me think the N-channel Isn't getting turned on fully to get back to ground quickly.