RF109

2400 MHz Digital Spread Spectrum Transceiver

6

Conexant

100646A

Conexant Proprietary

1/19/00

Interface Description

Table 2. RF109 Pin Signal Description (1 of 2)

Pin

Signal

Type

Description

18

TXEN

Input

Transmit Enable. Switches on/off bias power to the transmitter circuitry.

1: Tx on

0: Tx off

9

RXEN

Input

Receive Enable. Switches on/off bias power to the receiver circuitry.

1: Rx on

0: Rx off

46

SYNTHEN

Input

Synthesizer Enable. Switches on/off bias power to the synthesizer circuitry.

1: Synthesizer on

0: Synthesizer off

21

22

PS1

PS2

Input

Input

Transmit Power. These two control bits select the PA output power.

PS1=0, PS2=0: High (–8 dBm typical, single-ended)

PS1=0, PS2=1: Medium (–18 dBm typical, single-ended)

PS1=1, PS2=0: Low (–26.5 dBm typical, single-ended)

PS1=1, PS2=1: Undefined

10

LNAATTN

Input

LNA Attenuator. This control signal toggles the LNA gain between the low gain state and the high gain state.

1: Low gain, attenuator enabled

0: High gain, attenuator disabled

3

FREF

Input

Reference Oscillator. This digital input clock signal is used to provide the reference frequency for the synthesizer. A 9.6 MHz

clock provides channel spacing of 1.8 MHz (see Table 1).

2

CLK

Input

Synthesizer Programming Clock. This is the clock input signal used to serially shift the synthesizer data bits into the

synthesizer input register. The rising edge of CLK is used to load each data bit.

4

DATA

Input

Synthesizer Programming Data. This is the serial data input bit stream used to program the synthesizer. Data bits are shifted

from MSB first to LSB. The DATA bit is loaded into the synthesizer input register on the rising edge of the CLK signal.

47

STROBE

Input

Synthesizer Programming Strobe. This signal is used to transfer the synthesizer data bits from the input register to the pulse

swallow counter, after all of the data bits have been shifted in. The data is transferred on the rising edge of the STROBE signal.

Analog Signals

8

TXD

Input

Transmit Data. This input signal is used as the modulating signal. TXD is a single-ended, 1.2 Mbps NRZ signal from the

baseband modem. The TXD signal shall be filtered first if any data/spectral shaping is desired. A resistor divider should be used

to provide the desired signal level at the TXD input of the RF109.

5

TXREF

Input

Tx Reference. This is the reference for the TXD input. It is AC-coupled to ground.

23

GCREF

Input

Gain Control Reference. This is the reference for the gain control input. It is connected to ground.

28

29

RXI-

RXI+

Output

Output

Received In-Phase Signal Negative, Received In-Phase Signal Positive. This differential signal pair is the in-phase portion of

the baseband output of the receiver. The differential output signal level is typically 0.5 Vp-p, within the AGC operating range of

1.35–1.9 V.

26

27

RXQ-

RXQ+

Output

Output

Received Quadrature Signal Negative, Received Quadrature Signal Positive. This differential signal pair is the quadrature

portion of the baseband output of the receiver. The differential output signal level is typically 0.5 Vp-p, within the AGC operating

range of 1.35–1.9 V.

24

AGC

Input

Auto Gain Control. This analog input signal is used to control the gain of the baseband VGAs in the receiver. This signal is

generated by the baseband ASIC as part of the AGC control loop. An increase in the AGC voltage decreases the baseband VGA

gain. The control loop provides a typical receive baseband differential signal of 0.5 Vp-p over the VAGC range of 1.35–1.9 V.

38

39

VCO1

VCO2

Input

Input

Voltage Controlled Oscillator. This differential input provides the local oscillator signal from an external VCO to the RF109

mixers. An external BALUN may be used to convert a single-ended external VCO signal to the differential signals, VCO1 and

VCO2, required by the RF109. The differential input signal level required is typically 200 mVp-p.

43

CHPO

Output

Charge Pump Output. This output signal is used to control the external 2.4 GHz VCO. The CHPO current is typically ±250 µA.

11

LNAIN

Input

RF Input. This is the received RF input signal that is routed to the LNA of the RF109. This pin should be externally matched to

50

Ω. The received signal must be AC coupled into LNAIN with a 12 pF series capacitor.

15

16

RFO1

RFO2

Output

RF Output. These are the differential transmit output signals from the RF109. The single-ended output impedance is 50

Ω. The

RF output signals are internally AC-coupled. The unused signal should be terminated to ground through a 50

Ω resistor.