2.4GHz 802.11b Zero-IF Transceivers

12

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Pin Description

PIN

NAME

DESCRIPTION

1

VCC_LNA

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

bypass capacitor ground vias with other branches.

N.C.

No Connection. Not internally connected. (MAX2820 only)

2

VREF

Voltage Reference Output. (MAX2821 only)

3

RF_GAIN

LNA Gain Select Logic Input. Logic high for LNA high-gain mode, logic low for LNA low-gain mode.

4

RX_RFN

Receiver LNA Negative Input. On-chip AC-coupling. Requires off-chip impedance match and

connection to 2:1 balun.

5

RX_RFP

Receiver LNA Positive Input. On-chip AC-coupling. Requires off-chip impedance match and

connection to 2:1 balun.

6

VCC_REF

Supply Voltage for Bias Circuitry and Autotuner. Bypass with a capacitor as close to the pin as

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

7

RBIAS

Precision Bias Resistor Pin. Connect a 12k

Ω precision resistor (≤ 2%) to GND.

8

TX_RFP

match and connection to 4:1 balun.

9

TX_RFN

impedance match and connection to 4:1 balun.

10

PA_BIAS

Power-Amplifier Bias-Current Control Signal. Analog output. High-impedance, open-drain current

source. Connect directly to bias-current control input on external PA.

11

VCC_DRVR

Supply Voltage for Transmit Driver. Bypass with a capacitor as close to the pin as possible. Do not

share the bypass capacitor ground vias with other branches.

12

TX_GC

Transmit Gain-Control Input. Analog high-impedance input. Connect directly to baseband IC DAC

output. See the Typical Operating Characteristics for Transmitter Gain vs. Gain-Control Voltage.

13

VCC_TMX

Supply Voltage for Transmit Mixer and VGA. Bypass with a capacitor as close to the pin as possible.

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

14

TX_BBIN

Transmit Negative In-Phase Baseband Input. Analog high-impedance differential input. Connect

directly to baseband IC DAC voltage output. Requires a 1.2V common-mode voltage.

15

TX_BBIP

Transmit Positive In-Phase Baseband Input. Analog high-impedance differential input. Connect

directly to baseband IC DAC voltage output. Requires a 1.2V common-mode voltage.

16

TX_BBQP

Transmit Positive Quadrature Baseband Input. Analog high-impedance differential input. Connect

directly to baseband IC DAC voltage output. Requires a 1.2V common-mode voltage.

17

TX_BBQN

Transmit Negative Quadrature Baseband Input. Analog high-impedance differential input. Connect

directly to baseband IC DAC voltage output. Requires a 1.2V common-mode voltage.

18

VCC_TXF

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

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

19

GND_DIG

Digital Ground