Basic Operation
In the ideal OTA, the output current is a linear function of the differential input voltage, calculated as follows:
where Vin+ is the voltage at the non-inverting input, Vin− is the voltage at the inverting input and gm is the transconductance of the amplifier.
The amplifier's output voltage is the product of its output current and its load resistance:
The voltage gain is then the output voltage divided by the differential input voltage:
The transconductance of the amplifier is usually controlled by an input current, denoted Iabc ("amplifier bias current"). The amplifier's transconductance is directly proportional to this current. This is the feature that makes it useful for electronic control of amplifier gain, etc.
Read more about this topic: Operational Transconductance Amplifier
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