Why is a BJT slow to come out of saturation?

[uoficowboy]

So, my understanding with BJTs is that in a high speed circuit you never want to let them saturate as they take a while to de-saturate. I don't think the same applies to MOSFETs, right? What is the cause of this slow down?

Thanks!

 

[IanP]

What is the cause of this slow down?

When you saturate a transistor you forward bias the collector base junction and this stores a lot of charge in the base ..

You can use the Ebers-Moll model if you want to find out just how much charge you store, as well as all the voltages and currents and that allows you to analyze the switching speed of a saturated bipolar transistor ..

IanP
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