A 10-20GHz Wide Locking Range Multi-Phase Generator PLL for 80Gb/s Serial Data Communication

An 8-phase 20 GHz PLL has been designed for a serial transceiver. The PLL has a wide locking range from 10 GHz to 20 GHz with a phase noise of -112 dBc/Hz at 10 kHz offset. The PLL uses a four-stage ring oscillator that has a wide tuning range with a feedforward interpolation topology for coarse frequency tuning and a varactor diode load capacitance variation for fine frequency tuning. The PLL is fabricated in 0.13-mum SiGe BiCMOS technology.