If a bypass capacitor is used the voltage drop across emitter resistance is reduced which in turn increases the gain.....
The capacitor is called a bypass capacitor , it provides a low impedence path for AC emitter current to groun.
Without a bypass capacitor it is just equal to Rc
a capacitor that bypasses a BJT's emitter bias resistor so the emitter is at AC ground but has a DC bias voltage on it to set operating conditions. without the bypass, the bias would not stay constant.
The emitter bypass capacitor in a common emitter amplifier will have less resistance as the frequency increases. Since gain in this configuration is collector resistance divided by emitter resistance (within limits of hFe), the gain will thus increase for higher frequencies, making this into a high pass filter.
Gain in a CE configuration of a BJT is collector resistance divided by emitter resistance, subject to the limit of hFe. The emitter bypass capacitor will have lower impedance at high frequency, so the gain will be higher at higher frequency, making this a high-pass amplifier.
The emitter bypass capacitor, in a typical common emitter configuration, increases gain as a function of frequency, making a high pass filter. Removing the capacitor will remove the gain component due to frequency, and the amplifier will degrade to its DC characteristics.
In the common emitter configuration, gain is hFe or collector resistance divided by emitter resistance, whichever is less. Placing a capacitor across the emitter resistor effectively makes the emitter resistor less, for higher frequencies, so the gain is higher for higher frequencies. This creates a high pass filter, or a low cut filter, depending on what you want to call it.
The emitter resistor is there to provide DC bias to the base. If it is not bypassed, then the AC output signal is also dropped across this resistor, effectively lowering the output swing. When a bypass capacitor is added, the DC bias still flows through the resistor, but the capacitor acts as a short circuit for the AC signal, so that the AC signal is not reduced. The capacitor selected must be large enough so it appears as a very low resistance at the lowest frequency the amplifier will pass.
A: THE EMITTER resistor sole function is to provide stability if it is by passed by a capacitor then this resistance will change due to frequency since as frequency increases the impedance decreases. The total gain will change accordingly
Emitter bypass capacitor is a capacitor which provide low impedance to AC and high impedance to DC . AC is shunt then only DC appears on RC and volage gain increses.
A: A TRANSISTOR gain is determined by current flow on the collector by adding a resistor to the emitter this current flow is reduced by adding or bypassing this resistor with a capacitor the net effect is that this emitter resistor will be reduced in value as frequency increases therefore change gain as a function of frequency input
to bypass current and charge and discharge current