A versatile 90-nm CMOS charge-pump PLL for SerDes transmitter clocking

This paper presents a low-jitter charge-pump phase-locked loop (PLL) built in standard 90-mn CMOS for 1 to 10 Gb/s wireline SerDes transmitter clocking. The PLL employs a programmable dual-path loop filter with integral path and resistorless sample-reset proportional path that are independently controlled for flexible setting of closed-loop bandwidth and peaking. Frequency is synthesized by a digitally calibrated LC-VCO achieving 45% calibration tuning range with inversion-mode nMOS varactors and area-efficient helical inductors. Following calibration, 4.8% hold range compensates for VCO sensitivity to supply voltage and temperature drift. The PLL exhibits 0.81 ps rms jitter at 10 Gb/s. Critical for ASICs integrating noisy digital cores and multiple SerDes channels, design considerations to minimize jitter induced by supply noise are described. Deep-submicron CMOS effects on design are also examined to improve manufacturability and performance.