Identifying Parasitic Influences from Waveform

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threesheetsal

Joined Jul 19, 2019
3
I have the following circuit connected to a transformer via J2. The schotkys are not installed
The transformer goes to a glass chamber to produce Ozone by coronal discharge in the 5-20KHz and 5-20KV range

schematic.PNG

Below are a series of O-scope screen caps of the mosfet gate and drain terminals

1.) MOSFET gate with NO rectified AC applied
Notice after the pulse, the signal is completely flat straight

TEK00131.PNG

2.) MOSFET gate and drain WITH 10V 60Hz rectified AC applied (4.48% duty cycle)
It seems the signal on the drain is affecting the gate signal when the pulse goes low

TEK00127.PNG

3.) MOSFET gate and drain WITH 10V rectified AC applied (14.06% duty cycle)
TEK00128.PNG

4.) MOSFET gate and drain WITH 10V rectified AC applied (22.3% duty cycle)
TEK00129.PNG

5.) MOSFET gate and drain WITH 10V rectified AC applied (48.32% duty cycle)
TEK00130.PNG

Can anyone provide some insight as to why the gate is being affected when it goes low? Is this parasitic capacitance/inductance?
Here's by board layout
pcb.PNG
 

danadak

Joined Mar 10, 2018
3,630
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