The discussion focuses on maximizing gain in a bipolar transistor amplifier, specifically using a 2N3904 transistor. The output voltage (Vout) should theoretically be around 7.5V when biased correctly at the Q-point with a quiescent collector current of approximately 1mA. The presence of a 15µF capacitor is crucial for increasing output voltage and gain, as removing it reduces gain. To further enhance gain, cascading stages or employing a current source instead of a collector resistor is recommended.
PREREQUISITESElectronics engineers, hobbyists designing audio amplifiers, and students studying transistor amplifier configurations will benefit from this discussion.
The gain of that configuration is about -Rc/Re, where Re is the sum of the intrinsic emitter resistance re and the external emitter resistor. You can ground the emitter to maximize the gain, but then your bias point is not as stable over temperature and transistor component variations. Using the capacitor in parallel with the emitter resistor gives you an effective grounding of the emitter at frequencies above 1/2piRC, which gives you max gain there. If you need more gain, you will need to cascade (not cascode...) a couple stages in series, or use a current source instead of the collector resistor.math&science said:One more question, if you have an input but took out the 15microF capacitor, is it possible to increase the gain in any way? I know that if you take out the capacitor, you get a lower gain because that capacitor increases the output voltage.