because that's how God intended the way of the world to be..
180 degree phase shift
In a two stage RC coupled amplifier, the two transistors are identical and a common power supply is used. The input is provided to the first stage of the amplifier where it is amplified and this output is used as input for the second stage. This is amplied once again by the other transistor in the second stage and the final output is obtained. There will be a 180 degree phase shift after the first stage amplification which is nullified by the 180 degree phase shift of the second stage amplification.Thus, we obtain an output which is an amplified signal of the input and is in phase with the input signal.
In the common emitter amplifier, an increase of base-emitter current causes a larger increase of collector emitter current. This means that, as the base voltage increases, the collector voltage decreases. This is a 180 degree phase shift.
A transistor
The Class A common emitter BJT design has input on the base and output on the collector. This design is inverting, or 180 degrees phase shift.
Class b complementry symetry is nothing but the amplifier which have double amplification,in this the transistor used is npn and pnp so one get the phase shift of 180 and other also so the total phase shift is 360 degre.so it is very useful for the amplification purpose
A phase-shift oscillator using a PNP transistor consists of an RC network in the feedback path, a PNP transistor biased to operate in the active region, and a network of resistors and capacitors that provide the required phase shift for oscillation. The RC network introduces a 180-degree phase shift at the desired frequency, and the transistor provides the additional 180-degree phase shift needed for sustained oscillation. By properly selecting the values of resistors and capacitors, along with biasing the transistor correctly, a stable sinusoidal oscillation can be achieved.
no phase shift
A transistor does not act as an amplifier. It is used as a component in an amplifier circuit.
A phase-shift oscillator is a simple electronic oscillator circuit. It consists of an inverting amplifier element such as a transistor or op amp, with its output fed back into its input through an filterconsisting of a network of resistors and capacitors. The feddback network 'shifts' the phase of the amplifier output by 180 degrees at the oscillation frequency, to give positive feedback.[1] Phase shift oscillators are mostly used at lower frequencies, often in the audio frequency range as audio oscillators.
An amplifier needs at least one active device (transistor or op-amp), a feedback loop, and proper phase shift to create oscillations. The loop gain of the amplifier must be greater than or equal to one and the phase shift around the loop must be 360 degrees or a multiple of 360 degrees. Additionally, some form of energy storage (inductors or capacitors) is typically required in the feedback loop to sustain oscillations.
180 degree phase shift
The Junction Field Effect Transistor (JFET)exhibits characteristics which often make it more suited to a particular application than the bipolar transistor. Some of these applications are: - High Input Impedance Amplifier - Low-Noise Amplifier - Differential Amplifier - Constant Current Source - Analogue Switch or Gate - Voltage Controlled Resistor
A PNP transistor has no advantage or disadvantage over an NPN transistor in its ability as an amplifier. Rather, the current-handling capacities of the transistor determine if it's usable as an amplifier.
Current gain. At the cost of no voltage gain.
In a two stage RC coupled amplifier, the two transistors are identical and a common power supply is used. The input is provided to the first stage of the amplifier where it is amplified and this output is used as input for the second stage. This is amplied once again by the other transistor in the second stage and the final output is obtained. There will be a 180 degree phase shift after the first stage amplification which is nullified by the 180 degree phase shift of the second stage amplification.Thus, we obtain an output which is an amplified signal of the input and is in phase with the input signal.
In any transistor circuit , there is a phase shift. It takes a finite time for the controlling signal, usually on the base connection, to have an effect on the circuit and cause a change to the output. The shape of the signal remains but it is shifted in time (phase). The difference varies by configuration. It can be as much as180 degrees if the circuit is inverting the signal. The addition of passive components add to the shift.