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SPICE - analog simulation

Pictured here is a multi-stage linear, differential amplifier project.  It functions much like an operational amplifier, but is composed of discrete components.  It requires +15V and –15V DC power supplies and has two inputs, which I’ve labeled Vin1 and Vin2 (e.g. V(n08) and V(n09), respectively).  The circuit provides a voltage gain of approximately 19000x, while suffering 12 degree phase shift over the audio bandwidth.  As I said, it is basically a baby opAmp circuit.

I’ve included a schematic, netlist and SPICE small signal AC analysis.  The SPICE analysis plots V(n011) (the emitter of Q8) as a function of Vin1 and Vin2 (which are excited by sine waves 180 degrees out of phase with each other and varying in frequency from 20 to 20,000 Hz).

 

All images are “clickable” for closer examination.  This analysis was carried out using Linear Technologies LTSPICE IV. 

A multi-stage, linear, differential amplifier

Basically flat ~85db gain throughout the entire audio spectrum

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