Roger S. Countryman

A wide-bandwidth low-voltage PLL for PowerPC microprocessors

A 3.3 V Phase-Locked-Loop (PLL) clock synthesizer implemented in 0.5 /spl mu/m CMOS technology is described. The PLL supports internal to external clock frequency ratios of 1, 1.5, 2, 3, and 4 as well as numerous static power down modes for PowerPC microprocessors. The CPU clock lock range spans from 6 to 175 MHz. Lock times below 15 /spl mu/s, PLL power dissipation below 10 mW as well as phase error and jitter below /spl plusmn/100 ps have been measured. The total area of the PLL is 0.52 mm/sup 2/. >

A scalable resistor-less PLL design for PowerPC/sup TM/ microprocessors

A new resistor-less phase locked loop implemented in a 2.5 V, 0.35 /spl mu/m, CMOS technology is described. The design supports 13 different clock multiplier settings and uses a current-controlled-oscillator along with switched current sources to adjust the clock phase. Practical issues concerning system design and PLL stability parameters are also discussed. Simulation and characterization results show the response of the PLL to power supply and input clock modulation.