2400 MHz Digital Spread Spectrum Transceiver

RF109

100646A

Conexant

5

1/19/00

Conexant Proprietary

Recommendations on Layout and Implementation _______

A typical applications schematic is shown in Figure 5.

Decouple all Vcc pins as close as possible to the supply pin.

All ground pins should have minimum trace inductance to

ground. If a ground plane cannot be provided right at the pins,

the vias to the ground plane should be placed as close to the

pins as possible. There should be one via for each ground pin. If

the ground plane is at the bottom layer, it is recommended to

have two vias in parallel for each ground pin.

Connect all no connect (NC) pins to the ground.

VCC1 (pin 6), VCC2 (pin 7), VCC3 (pin 25), and VCC4 (pin 31)

should be connected to the common Vcc supply through

individual decoupling networks.

spectrum signal level of 0.10 Vp-p, to the TXD pin (pin 8).

The routing of the trace to pin 3 (FREF) is very important to

minimize the coupling of the reference clock (9.6 MHz) into the

LO. The FREF trace should be well isolated from all other

traces, preferably by grounded strips on either side of the trace.

All traces from the VCO to pins 38 and 39 should be as short as

possible with a characteristic impedance of 50

Ω.

Exposed Paddle Soldering ____________________________

The RF109 48-pin TQFP package has an exposed (metal)

paddle on the bottom. The footprint dimensions of the exposed

paddle are shown in Figure 6. The printed circuit board should

provide through hole connections to the ground plane to ground

the exposed paddle. The solder mask opening should have the

same size as the exposed paddle. All relevant manufacturing

considerations for this type of package should be taken into

account.

ESD Sensitivity______________________________________

The RF109 is a static-sensitive electronic device. Do not operate

or store near strong electrostatic fields. Take proper

Electrostatic Discharge (ESD) precautions.

CLK

FREF

DATA

1500pF

RXEN

LNAATTN

VBAT

0.047µF

8.2pF

STROBE

0.047

µF

Cservo

0.082µF

Cservo

0.082µF

10

Ω

VBAT

91

Ω

VREG

VCO

BALUN

100

Ω

91

Ω

VCO SHIELD AREA

12pF

12pF

VCC

GND

TUNE

OUT

GND

NC

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

0.01

µF

8.2

pF

VCC

GND2

OUT

CTRL

GND1

BYP

VBAT

VREG

10

Ω

8.2

pF

1.0pF

402

Ω

402

Ω

820pF

820pF

470

Ω

0.047

µF

1.2k

Ω

Rmod

2200

pF

12pF

12pF

Rgmc

390pF

0.01µF

10k

Ω

10k

Ω

330pF

TXD

825

Ω

82µH

3.6k

Ω

1.8pF

SYNTHEN

8.2pF

75 Ω

1500pF

3V REGULATOR

0.056µF

8.2

pF

1000

pF

8.2

pF

47

µF

1000

pF

10

Ω

10

Ω

PS1

PS2

AGC

RXI+

RXI-

RXQ+

RXQ-

LNAIN

RFO1

RFO2

TXEN

+

-

47

pF

47nF

47nF

8.2pF

8.2pF

8.2pF

0.01µF

47nF

8.2pF

8.2pF

8.2pF

8.2pF

8.2pF

Figure 5. Typical Application Diagram – RF109