# Switching and amplifiers

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##### Newbie level 3
Thanks For your reply , But i didnt get the answer completely, The question was about a circuit that NEVER goes to saturation region. im looking for the circuit it self, or schematic diagram of the circuit.
thanks anyway

#### FvM

##### Super Moderator
Staff member
Your question is raising several doubts:
- the term saturation has a different meaning for BJT and MOS transistors, so it's not clear which operation region of transistors you actually mean

I assume, that you mean saturation as it's used for BJT.

- I don't agree to the conclusion, because the operation of some high speed logic circuits is usually descibed as non-saturated switching.

Anyway, it's not clear to me, which kind of circuit you are actuall looking for?

$h@ri ###$h@ri

Points: 2

#### chuckey

As all devices are limited in their output by their supply lines, i.e. you can't get 20V out of an amplifier that has a 5V supply line, the only way to proceed is to use a logerithmic amplifier, even these will run out of head room but their dynamic range is very wide.
Frank

#### \$h@ri

##### Newbie level 3
Thanks FVM,
By the Word "saturation" , i exactly meant saturation as used for BJTs. is it possible to have a circuit configuration for A BJT transistor that never reaches saturation region?
about non-saturated switching, thanks alot, ill search about those high speed logic gates,
Thanks once again.

#### FvM

##### Super Moderator
Staff member
I think the basic scheme for non-saturated switching is a differential amplifier. It performs current steering to the outputs without saturation (assume Vce > Vbe for simplicity). ECL logic is basically using this operation mode.

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