RE: 10+MHz SSTC Gate Drive Circuit Finalized

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Original poster: "Mccauley, Daniel H" <daniel.h.mccauley-at-lmco-dot-com> 


Ken,

The mistake was that the P-Channel FET was just placed backwards on the
schematic. It will work fine
once you switch it around.  Also, though you really don't need a 10 ohm
resistor there, you need it
for any shoot-through conditions between the P-Channel FET and the NPN
transistor.

Dan



 > I tried simulating the circuit (in SIMetrix, -at- 100 KHz) & couldn't get
 > much out of it!  I thought to change it a bit & submit my
 > schematic, via
 > hot-streamer, at http://hot-streamer-dot-com/temp/ssdrvr-kch.pdf.
 >
 > A 20 V pp source drives the xfmr, simulating the "monster"
 > circuit.  In
 > the top secondary ckt, D1, C2 & Q1 are as before except C1's
 > capacitance
 > is much reduced (1 uF takes forever to charge; I'd be worried
 > about those
 > 1st few cycles as to MOSFET drive).  The MOSFET/10-ohm branch
 > is replaced
 > by Q2 and both Q1 & Q2 are driven via the D3/R1 pair.  D3
 > provides max.
 > drive for + excursions while R1 limits xfmr current during "-"
 > excursions.  (Without R1, Q2's b:c junction will short out TX1.)  R3
 > simulates TX1's resistance & R6 is for parasitic suppression
 > (in the real
 > ckt).  R2 damps oscillation a bit.
 >
 > Ken Herrick
 >
 >
 >