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Registered Member #33
Joined: Sat Feb 04 2006, 01:31PM
Location: Norway
Posts: 971
Sigurthr wrote ...
Just make a simple TTL inverter (NPN, pull up on collector) and use two non-inverting drivers.
Bipolar transistors take a while to come out of saturation, and an inverter made with one can easily take several microseconds to turn off. At typical SSTC frequencies, this can be a large fraction of a cycle, so the circuit will not function correctly, there is some good info here: . The same circuit made with a MOSFET will work much better. An inverter IC like the 74HC14 would be somewhat faster again, and have more symmetrical delay.
Thank you Wolfram, that is actually very valuable information. The nanosecond (and often, single microsecond) scale is hidden from me as I lack the equipment to visualize it.
I've used simple BJT inverters in SSTC drive circuits before, but only as stop-gaps until I got proper gate chips in, guess I just got lucky with the f0.
Registered Member #39190
Joined: Sat Oct 26 2013, 09:15AM
Location: Boise National Forest
Posts: 65
Wolfram wrote ... Bipolar transistors take a while to come out of saturation...
...which is a good reason not to drive them into saturation. Hence accommodations like Baker clamps or a reverse-biased Schottky diode between base and collector.
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Fullbridge SSTC Design Questions
