Inter-Stage Coupling Capacitor

AnalogKid

Joined Aug 1, 2013
8,138
You don't say what you want the values to achieve. For example, if you want flat frequency response within the passband, then the R-C corner frequency should be at least one octave below the lowest frequency of interest. If you want a high-pass roll off to limit the output bandwidth, such as in a telecom application, then reducing the coupling or feedback capacitor size can achieve this.

In both cases, the equation above is the one to use. For the feedback cap CF, R is the sum of the stage 2 output impedance, the feedback resistor RF1, and the impedance at the Q1 emitter. For the coupling cap C13, R is the sum of the stage 1 output impedance and the stage 2 input impedance.

ak
 
Top