TRF2020

SYNTHESIZER FOR GLOBAL SYSTEM

FOR MOBILE (GSM) CELLULAR TELEPHONES

SLWS020B – FEBRUARY 1995 – REVISED JANUARY 1998

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POST OFFICE BOX 655303

Synthesizers

Communications (GSM) Applications

description

The Texas Instruments (TI

™) TRF2020 is an

integrated high performance frequency synthe-

sizer device. The TRF2020 consists of one main

1.2-GHz synthesizer and two auxiliary 250-MHz

synthesizers. Each synthesizer has an independent dual-modulus prescaler and separate powerdown modes.

These features provide maximum flexibility for the design of 900-MHz wireless systems.

The main synthesizer consists of a 32/33-modulus prescaler with an 11-bit counter, a phase-frequency detector,

and a charge pump. The phase-frequency detector is referenced to an internal reference frequency that is

derived from an external TCXO signal. The phase-frequency detector is also provided with a dead-zone

compensation circuit that reduces synthesizer phase noise during locked conditions.

Each auxiliary synthesizer consists of an independent 8/9-modulus prescaler with an 11-bit counter, a

phase-frequency detector, and a charge pump. Similar to the main synthesizer, each auxiliary synthesizer’s

phase-frequency detector is referenced to an internal reference frequency that is derived from an external

TCXO signal.

The external TCXO signal is prescaled by an 11-bit counter and then distributed to three independent

postscalers. Each postscaler provides a selectable, divide-by-1, -2, -4, or -8 function before the reference signal

is distributed to the associated synthesizer phase detector. The reference frequency prescaler and independent

postscalers are software programmable.

To achieve minimum lock-up time, each synthesizer contains a speed-up mode charge pump capable of

providing 2 mA output current and an analog switch that can change the loop-filter time constant. The duration

of the speed-up mode operations can be independently controlled with software.

The states of the three internal lock detectors are provided on a programmable, combinational logic output; each

synthesizer can be selected independently or ANDed together.

The device is programmed over a three- wire, synchronous, serial data bus (clock, data, strobe) with achievable

bit rates as high as 20 Mbits/sec. The data is partitioned into words in such a manner that static parameters may

be sent once during initialization, and dynamic parameters, such as frequency, may be sent as often as needed.

The TRF2020 is offered in a 24-pin plastic thin-shrink small-outline package (TSSOP) and is characterized for

free-air operation from – 40

°C to 85°C.

These devices have limited built-in ESD protection. The leads should be shorted together or the device placed in conductive foam

during storage or handling to prevent electrostatic damage to the MOS gates.

Copyright

© 1998, Texas Instruments Incorporated

PRODUCTION DATA information is current as of publication date.

Products conform to specifications per the terms of Texas Instruments

standard warranty. Production processing does not necessarily include

testing of all parameters.

Please be aware that an important notice concerning availability, standard warranty, and use in critical applications of

Texas Instruments semiconductor products and disclaimers thereto appears at the end of this data sheet.

TI is a trademark of Texas Instruments Incorporated.

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CLOCK

DATA

STROBE

LD

REF_IN

PDA2

SW2

AUX2_IN

AUX1_IN

PDA1

SW1

RPA

SWM

PDM

RPM

RF_IN

PW PACKAGE

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