LMX2335/LMX2336/LMX2337

Personal Communications

LMX2335

1.1 GHz/1.1 GHz

LMX2336

2.0 GHz/1.1 GHz

LMX2337

550 MHz/550 MHz

General Description

The LMX2335, LMX2336 and LMX2337 are monolithic, inte-

grated dual frequency synthesizers, including two high fre-

quency prescalers, and are designed for applications requir-

ing two RF phase-lock loops. They are fabricated using

National’s ABiC IV silicon BiCMOS process.

The LMX2335/36/37 contains two dual modulus prescalers.

A 64/65 or a 128/129 prescaler can be selected for each RF

synthesizer. A second reference divider chain is included in

the IC for improved system noise. LMX2335/36/37, which

employ a digital phase locked loop technique, combined with

a high quality reference oscillator and loop filters, provide the

tuning voltages for voltage controlled oscillators to generate

very stable low noise RF local oscillator signals.

Serial data is transferred into the LMX2335/36/37 via a three

wire interface (Data, Enable, Clock). Supply voltage can

range from 2.7V to 5.5V. The LMX2335/36/37 feature very

low current consumption; LMX2335/37 −10 mA at 3V,

LMX2336 −13 mA at 3V. The LMX2335/37 are available in

both a JEDEC SO and TSSOP 16-pin surface mount plastic

package. The LMX2336 is available in a TSSOP 20-pin sur-

face mount plastic package.

Features

n 2.7V to 5.5V operation

n Low current consumption

n Selectable powerdown mode:

I

n Dual modulus prescaler: 64/65 or 128/129

n Selectable charge pump current levels

Applications

n Cellular telephone systems (AMPS, ETACS, RCR-27)

n Cordless telephone systems (DECT, ISM, PHS, CT-1+)

n Personal Communication Systems

(DCS-1800, PCN-1900)

n Dual Mode PCS phones

n CATV

n Other wireless communication systems

Functional Block Diagram

DS012332-1

September 1996

© 1999 National Semiconductor Corporation

DS012332

www.national.com