Electronics > Projects, Designs, and Technical Stuff
High-voltage, high-speed pulse generator
mbless:
--- Quote from: David Hess on June 08, 2020, 04:46:12 am ---I would use a completely different topology but you seem to be restricted to improving this one.
--- End quote ---
After I have a working baseline, I can change as much as I want as long as it's reliable. So suggest away :-+
David Hess:
--- Quote from: mbless on June 08, 2020, 01:03:31 pm ---
--- Quote from: David Hess on June 08, 2020, 04:46:12 am ---I would use a completely different topology but you seem to be restricted to improving this one.
--- End quote ---
After I have a working baseline, I can change as much as I want as long as it's reliable. So suggest away :-+
--- End quote ---
I would replace the drain resistor with an active pull-up to make the output push-pull. AC coupling from the drive to the lower transistor can drive the upper transistor. However this change might not provide any advantage in your application.
An example of this sort of design can be found in the z-axis amplifier used for analog oscilloscopes which easily meets your performance requirements but with a much lighter load. Z-axis amplifiers are also linear so stable in their linear range which is not required in a pulse amplifier which leaves open the possibility of faster performance.
mbless:
I started laying out the baseline PCB and had some layout questions.
1. Is there an issue with a ground plane surrounding high-speed, high-current switching? This PCB is switching 500V into a 10Ohm resistor for 50-500ns with estimated 10ns edges. The attached images show a 3D view of the AC-coupled MOSFET gate driver, the top PCB layer (red) and the bottom layer (green). The blue line in the Top Layer image is the high-voltage path from the connector, through capacitors, through mosfet, and to resistor. Because the top layer is rather bare, I have a ground pour taking up the remaining space. (Note that I haven't done any via stitching yet.) My concern is if the fast, high-current switching will inject noise into the ground planes surrounding the high-current path. Most of what I have seen deals with removing ground planes around circuits sensitive to parasitic capacitance, so I am unsure of this scenario.
2. The Art of Electronics x Chapters discussed earlier have a high-voltage monitor circuit shown in the last attached image. What is intended with the "shield." Is it supposed to be a via-stitched ground trace surrounding the components with little openings for the input & output?
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