2.4GHz 802.11b Zero-IF Transceivers

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13

Pin Description (continued)

PIN

NAME

DESCRIPTION

20

VCC_DIG

Supply Voltage for Digital Circuitry. Bypass with capacitor as close to the pin as possible. Do not

share the bypass capacitor ground vias with other branches.

21

N.C.

No Connection. Not internally connected.

22

ROSCP

Reference Oscillator Positive Input. Analog, high-impedance differential input. DC-coupled. Requires

external AC-coupling. Connect an external reference oscillator to this analog input.

23

ROSCN

Reference Oscillator Negative Input. Analog, high-impedance differential input. DC-coupled.

Requires external AC-coupling. Bypass this analog input to ground with capacitor for single-ended

operation.

24

DIN

3-Wire Serial Interface Data Input. Digital, high-impedance input. Connect directly to baseband IC

serial interface CMOS output. (SPI/QSPI/MICROWIRE compatible)

25

SCLK

3-Wire Serial Interface Clock Input. Digital, high-impedance input. Connect this digital input directly to

baseband IC serial interface CMOS output. (SPI/QSPI/MICROWIRE compatible).

26

CSB

3-Wire Serial Interface Enable Input. Digital, high-impedance input. Connect directly to baseband IC

serial interface CMOS output. (SPI/QSPI/MICROWIRE compatible)

27

VCC_CP

Supply Voltage for PLL Charge Pump. Bypass with capacitor as close to the pin as possible. Do not

share the bypass capacitor ground vias with other branches.

28

CP_OUT

PLL Charge-Pump Output. Analog, high-impedance output. Current source. Connect directly to the

PLL loop filter input.

29

GND_CP

PLL Charge-Pump Ground. Connect to PC board ground plane.

30

GND_VCO

VCO Ground. Connect to PC board ground plane.

31

TUNE

VCO Frequency Tuning Input. Analog voltage input. High impedance. Connect directly to the PLL

loop filter output.

32

BYP

VCO Bias Bypass Pin. Bypass with a 2000pF capacitor to ground.

33

VCC_VCO

Supply Voltage for VCO. Bypass with capacitor as close to the pin as possible. Do not share the

bypass capacitor ground vias with other branches. Important note: Operate off separate regulated

supply voltage.

34

VCC_LO

Supply Voltage for VCO, LO Buffers, and LO Quadrature Circuitry. Bypass with capacitor as close to

the pin as possible. Do not share the bypass capacitor ground vias with other branches.

35

VCC_RXF

Supply Voltage for Receiver Baseband Filter. Bypass with capacitor as close to the pin as possible.

Do not share the bypass capacitor ground vias with other branches.

36

SHDNB

Active Low Shutdown Input. Digital CMOS input. High impedance. Connect directly to baseband IC

mode control CMOS output. Logic low to disable all device functions. Logic high to enable normal

chip operation.

37

DOUT

Serial Interface Data Output. Digital CMOS output. Optional connection.

38

RX_1K

Receiver 1kHz Highpass Bandwidth Control. Digital CMOS input. Connect directly to baseband IC

CMOS output. Controls receiver baseband highpass -3dB corner frequency; logic low for 10kHz,

logic high for 1kHz. See the Applications Information section for proper use of this function.

SPI and QSPI are trademarks of Motorola, Inc.

MICROWIRE is a trademark of National Semiconductor Corp.