Product Description
The PE3291 is a dual fractional-N FlexiPowerTM phase-lock loop (PLL) IC designed for frequency synthesis. Each PLL includes a FlexiPowerTM prescaler, phase detector, charge pump and on board fractional spur compensation.
The FlexiPower prescalers are supplied power on dedicated pins and can operate at a substantial power savings at voltages as low as 0.8 volts, while allowing a 3 volt charge pump supply. For 3 volt only systems, on-chip voltage regulation may be used to generate the prescaler power supplies.
Figure 1 illustrates the implementation of the FlexiPower
technology. The prescaler power supply may be provided externally or internally regulated down from VDD. In a typical 950 MHz application the total current consumed by the PLL is 2.1 mA. Operation at reduced current levels provides significant battery life extension. The PE3291 allows the system designer to minimize power consumption by controlling the voltage on the prescaler. For additional operating speeds and current consumptions refer to Figures 5 and 6.
PE3291 provides fractional-N division with power-of-two denominator values up to 32. This allows comparison frequencies up to 32 times the channel spacing, providing a lower phase noise floor than integer PLLs. The 32/33 RF prescaler (PLL1) operates up to 1200 MHz and the 16/17 IF prescaler (PLL2) operates up to 550 MHz.
The PE3291 Phase Locked-Loop is manufactured on Peregrine’s UltraCMOS™ process, a patented variation of silicon-on-insulator (SOI) technology on a sapphire substrate, offering the performance of GaAs with the economy and integration of conventional CMOS.

FEATUREs
• Ultra-Low Power via FlexiPower variable supply voltages
• Modulo-32 fractional-N main counters
• On-board fractional spur compensation: No tuning required, stable over temperature
• Improved phase noise compared to integer-N architectures

APPLICATIONs
• CDMA handsets
• CDMA base stations
• Analog Cordless phones
• One and two way pagers