TRF6903

SINGLECHIP MULTIBAND RF TRANSCEIVER

SWRS022D − MARCH 2004 − REVISED JUNE 2005

3

POST OFFICE BOX 655303

transmitter

The transmitter consists of an integrated VCO and tank circuit, a complete integer-N synthesizer, and a power

amplifier. The dividers, prescaler, and reference oscillator require only the addition of an external crystal and

a loop filter to provide a complete PLL with a typical frequency resolution of better than 200 kHz.

Since the typical RF output power is approximately 8 dBm, no additional external RF power amplifier is

necessary in most applications.

Four attenuation settings for the power amplifier are offered. This feature allows the user to fine tune the

amplifier for optimal output power.

receiver

The integrated receiver is intended to be used as a single-conversion FSK/OOK receiver. It consists of a low

noise amplifier, mixer, limiter, FM/FSK demodulator with an external LC tank circuit or ceramic resonator, LPF

amplifier, and a data slicer with clock recovery and an integrated data bit synchronizer. The received strength

signal indicator (RSSI) can also be used for fast carrier sense on/off keying, or amplitude shift keying,

(OOK/ASK) demodulator.

baseband interface

The TRF6903 can easily be interfaced to a baseband processor such as the Texas Instruments MSP430

ultralow-power microcontroller (see Figure 1). The TRF6903 serial control registers are programmed by the

MSP430 and the MSP430 performs baseband operations in the software.

A synchronized data clock, programmable for most common data rates, is provided by the TRF6903. This

feature reduces the need for extensive oversampling and data decision in the microcontroller during receive.

During transmit, the data clock can be used to clock the transmit data from the microcontroller to the TRF6903

at predefined data rates.

Data Clock

Transmit Data

Receive Data

Mode Select

Serial Control Data

Serial Control Clock

Serial Control Strobe

TX_DATA

RX_DATA

MODE

STDBY

DATA

CLOCK

STROBE

LNA_IN1, 2

PA_OUT

TRF6903

Transceiver

+

Discretes

RF Section

MSP430

Family

µC

Microcontroller

Section

Antenna

Standby

RF In

RF Out

RSSI Out (Analog Signal)

RSSI_OUT

Lock Detect Out

LOCK_DETECT

Brownout Detector Out

DET_OUT

Learn/Hold Select

LEARN/HOLD

DCLK

Receive Data Flag

RX_FLAG

Figure 1. System Block Diagram for Interfacing to the MSP430 Microcontroller