SLWS020B - FEBRUARY 1995 - REVISED JANUARY 1998
The Texas Instruments (TITM) TRF2020 is an integrated high performance frequency synthesizer 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.
View more information about generic part numbers:TRF2020
Go to the Engineering Design Center to locate information on other TI Semiconductor devices.