3291-04 데이터 시트보기 (PDF) - Peregrine Semiconductor

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3291-04

1.2 GHz / 550 MHz Dual Fractional-N FlexiPower PLL for Frequency Synthesis

Peregrine Semiconductor 

Product Description

The PE3291 is a dual fractional-N FlexiPower phase-lock

loop (PLL) IC designed for frequency synthesis and

fabricated on Peregrine’s patented UTSi® CMOS

process. 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 2.1mA. 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 1.2 GHz

and the 16/17 IF prescaler (PLL2) operates up to 550

MHz.

Applications

• CDMA handsets

• CDMA base stations

• Analog Cordless phones

• One and two way pagers

PRODUCT SPECIFICATION

PE3291

1.2 GHz / 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 temp.

• Improved phase noise

compared to integer-N

architectures

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

Regulator

Low

Speed Counters

Prescaler

PE3291

PEREGRINE SEMICONDUCTOR CORP.  | http://www.peregrine-semi.com

Copyright  Peregrine Semiconductor Corp. 2001

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