DiscreteTransistor AC Op-AMP Circuit
See our other Circuits.
This circuit is an inverting descrete transistor ac op-amp. It doesn't pass DC signals. The gain is set by the feedback resistor R2 and input resistor R1. The transistor amp is a very high gain amplifier. D1 is a bias Diode. So the base of Q2, and collector of Q3 is biased at about 4V. The low pass filter R4 and C3 is a compensation network to stop oscillations. C2 and C1 block DC and pass AC through the circuit.
Since the the circuit has such high gain, the base of Q2 looks like a virtual AC ground, because Vout/infiity= 0V. Thus, any AC current flowing in R1 also flows through R2.
Vout/Vin = -R2/R1
Vout/Vin = -(R2/R1)
Do you need help with an electronics design? Daycounter provides contract electronics design services. Contact us to give you a quote on your electronics design project.
Salt Lake City, UT, USA
Disclaimer: Daycounter, Inc. doesn't guarantee the accuracy of any of it's content. Use at your own risk.