Mumbai University > Computer Engineering > Sem 3 > Electronic Circuits and Communication Fundamentals

Marks: 5 Marks

Year: Dec 2015

Phase shifter circuit in RC phase shift oscillator for 180° phase shift consists of three RC elements. Similarly, to provide 90° phase shift between the two signals is difficult to define and design by using a simple .RC circuit.

The phase shift between input signal Vin and output signal Vout is introduced by PLL. Phase shifts of magnitudes from 0° to 180° can be achieved by varying the free-running frequency of VCO. Further, phase shifter circuit to produce 0° to 180° phase shift is shown in Fig.

1. In AM detector circuit, carrier signal in PLL undergoes 90° phase shift in the feedback loop by the time it is applied to multiplier.
2. Therefore, an additional phase shift of 90° has to be introduced to the incoming AM signal before applying it to PD for AM detection process to take place. Such situation demand in some more modulation circuits.