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3291-00

1200 MHz / 550 MHz Dual Fractional-N FlexiPower™ PLL for Frequency Synthesis

Peregrine Semiconductor 

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.

Product Specification

PE3291

1200 MHz / 550 MHz Dual

Fractional-N FlexiPower™ PLL

for Frequency Synthesis

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

Figure 1: FlexiPower technology enables

the prescaler to operate at voltages down to

0.8 volts. This significantly reduces the total

power.

To Loop Filter

3 Volts

0.8 3 Volts

Ref.

Input

Phase Comparator

and

Charge pump

Low

Speed Counters

Regulator

Prescaler

PE3291

Document No. 70-0009-04 │ www.psemi.com

©2005 Peregrine Semiconductor Corp. All rights reserved.

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