TRF2020 Datasheet, PDF (1/26 Pages) Texas Instruments – SYNTHESIZER FOR GLOBAL SYSTEM FOR MOBILE GSM CELLULAR TELEPHONES

TRF2020
SYNTHESIZER FOR GLOBAL SYSTEM
FOR MOBILE (GSM) CELLULAR TELEPHONES
SLWS020B – FEBRUARY 1995 – REVISED JANUARY 1998
D Three Separate Loops: 1 UHF and 2 VHF
PW PACKAGE
D Operation to 1.2-GHz for Main Synthesizer
(TOP VIEW)
D Operation to 250 MHz for Auxiliary
Synthesizers
D Fast Lock-up Time
D High-Speed Serial Data Bus
D Low Power Consumption
D Ideal for Global Systems for Mobile
V_DD
1
CLOCK
2
DATA
3
STROBE
4
LD
5
V_SS
6
REF_IN
7
24
AUX1_IN
23
V_DDP1
22
PDA1
21
SW1
20
RPA
19
V_DDA
18
SWM
Communications (GSM) Applications
description
The Texas Instruments (TI™) TRF2020 is an
V_SSP
8
PDA2
9
SW2
10
V_DDP2
11
AUX2_IN
12
17
PDM
16
V_SSA
15
RPM
14
V_DDPM
13
RF_IN
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.
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.
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.
Copyright © 1998, Texas Instruments Incorporated
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