Implementing compact current mode logic (CML) inductor capacitor (LC) voltage controlled oscillator (VCO) for high-speed data communications

摘要

A method and a phase locked loop (PLL) circuit for implementing compact current mode logic inductor capacitor voltage controlled oscillator for high speed communications, and a design structure on which the subject circuit resides are provided. The PLL circuit includes a current mode logic (CML) inductor capacitor (LC) Voltage Controlled Oscillator (VCO). The PLL circuit includes a reference circuit generates a virtual ground node for biasing noise sensitive components, providing level shifted VCO increment and decrement tuning values from a phase detector coupled by a respective resistor to tune a varactor of the LC VCO, and providing a loop filter function. The virtual ground node tracks a logic power supply noise, incurring no jitter penalty, and eliminating the need for a separate power supply for the PLL circuit.