transistors out of saturation in an op amp

Thread Starter

jsnx

Joined Mar 17, 2022
21
Hello, what would happen if, in my operational amplifier, some transistors are not in saturation at a certain input voltage? I find it quite hard, nearly impossible, to maintain tall the transistors in the saturation region for every input voltage, some of my transistors leave the saturation region when I have a -2V voltage in the inputs.
 

Papabravo

Joined Feb 24, 2006
18,770
Hello, what would happen if, in my operational amplifier, some transistors are not in saturation at a certain input voltage? I find it quite hard, nearly impossible, to maintain tall the transistors in the saturation region for every input voltage, some of my transistors leave the saturation region when I have a -2V voltage in the inputs.
What makes you think the transistors need to be in saturation?
 

Audioguru again

Joined Oct 21, 2019
4,794
Jsnx did not show a schematic with parts values.

With the input at -2V, the supply is +10V and -10V and the gain of the opamp is set at 1 then the output will be not saturated at +2V or -2V.
With the input at -2V, the supply is +10V and -10V and the gain of the opamp is set at 1000 then the output will be saturated at a positive or negative voltage as high as it can go.

Maybe he is talking about Mosfet transistors that are linear when saturated.
 

Papabravo

Joined Feb 24, 2006
18,770
Jsnx did not show a schematic with parts values.

With the input at -2V, the supply is +10V and -10V and the gain of the opamp is set at 1 then the output will be not saturated at +2V or -2V.
With the input at -2V, the supply is +10V and -10V and the gain of the opamp is set at 1000 then the output will be saturated at a positive or negative voltage as high as it can go.

Maybe he is talking about Mosfet transistors that are linear when saturated.
Was the TS talking about the output transistors or all of the transistors?
 
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