Contents Introduction
Voltage controlled oscillator (VCO) associated with phased-locked loop (PLL) is indispensable to most of the communication systems (using a high frequency carrier to transmit and receive data) for a channel or band selection. Phase noise requirements for the VCO is so stringent that many systems often use a discrete oscillator with a discrete transistor that has a good flicker noise performance. As the number of users increases in the shared bandwidth, the radio receiver must be designed with careful considerations to a local oscillator phase noise in the receiver to avoid reciprocal mixing due to the poor phase noise of the VCO and large undesirable signals near the desired band or channel [1].
