Data Sheet

Doc. No. 100646A

Conexant Proprietary

January 19, 2000

RF109

2400 MHz Digital Spread Spectrum Transceiver

The RF109, a fully integrated transceiver device, provides the transmit, receive, and

frequency synthesis functions for 2400 MHz digital spread spectrum systems operating

in the 2400–2483.5 MHz portion of the ISM (Industrial, Scientific, Medical) band. The

device has a direct conversion architecture that minimizes circuit complexity and cost.

The receive path of the RF109 provides complete RF-to-baseband I/Q demodulation,

including an LNA, double-balanced quadrature mixers, fully integrated baseband filters,

and baseband variable-gain amplifiers. The transmit path is a variable-gain direct

conversion modulator. Figure 1 shows the RF109’s pin signals. Figure 2 shows the

RF109 block diagram.

The RF109 generates the Local Oscillator (LO) frequencies using a Phase Lock Loop

(PLL) frequency synthesizer and an external 2.4 GHz Voltage Controlled Oscillator

(VCO). The PLL provides a full frequency range of 2392.2–2505.6 MHz.

The RF109 features low-voltage operation (3.0–4.5V) for low power consumption. A

complete RF system solution for 2.4 GHz cordless telephone applications can be

constructed with the RF109, a power amplifier, a differential 2.4 GHz frequency source

and a Transmit/Receive (T/R) switch.

RF109

1

2

3

4

5

6

7

8

12

9

10

11

36

35

34

33

32

31

30

29

25

28

27

26

CLK

NC1

FREF

TXD

VCC2

VCC1

TXREF

DATA

LNAATTN

RXEN

LNAIN

NC2

RXQ-

NC3

VCC3

SRI+

GND3

VCC4

SRQ-

SRQ+

SRI-

RXI-

RXI+

RXQ+

Figure 1. RF109 Pin Signals

Features

• Low power dissipation

• Fast settling from standby mode to active

mode

• Separate enable lines for transmit, receive,

and synthesizer

• 64 programmable channels with 1.8 MHz

channel spacing

• 3-battery-cell operation

• 48-pin TQFP package with exposed paddle

(refer to Figure 6)

• Receiver

− LNA/Quadrature mixer from RF down to

baseband

− Selectable LNA gain

− Integrated baseband filter with external

bandwidth adjustment

− Receiver baseband amplifier with

automatic gain control

− Direct conversion with differential

baseband outputs

− Low system noise figure (9.0 dB typical)

− Large dynamic range (89 dB typical)

• Transmitter

− Variable gain modulator

− Mixer for baseband-to-RF modulation

− Differential TX inputs and outputs

− Selectable transmitter output levels for

high, medium, and low power modes

Applications

• Digital Spread Spectrum (DSS) cordless

telephone

• Direct sequence spread spectrum systems

• Frequency hopping spread spectrum

systems

• Wireless LANs

• Wireless modems

• Wireless security

• Inventory control systems