MAX2832 datasheet(21/34 Pages) MAXIM

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2.4GHz to 2.5GHz 802.11g/b

RF Transceivers with Integrated PA

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Detailed Description

The MAX2831/MAX2832 single-chip, low-power, direct

conversion, zero-IF transceivers are designed to support

802.11g/b applications operating in the 2.4GHz to

2.5GHz band. The fully integrated transceivers include a

receive path, transmit path, voltage-controlled oscillator

(VCO), sigma-delta fractional-N synthesizer, crystal oscil-

lator, RSSI, PA power detector (MAX2831), temperature

sensor, Rx and Tx I/Q error-detection circuitry, baseband-

control interface and linear power amplifier (MAX2831).

The only additional components required to implement a

complete radio front-end solution are a crystal, a pair of

baluns, a BPF, a switch, and a small number of passive

components (RCs, no inductors required).

Receiver

The fully integrated receiver achieves a noise figure of

2.6dB in high-gain mode, and an input compression point

of -6dBm in low-gain mode, while consuming only 62mA

of supply current. The receiver integrates an LNA and

VGA with a 95dB digitally programmable gain control

range, direct-conversion downconverters, I/Q baseband

lowpass filters with programmable LPF corner frequen-

cies, analog RSSI and integrated DC-offset correction cir-

cuitry. A logic-low on the RXTX input (pin 48) and a

logic-high on the SHDN input (pin 12) enable the receiver.

LNA Input Matching

The LNA features a differential input that is internally

AC-coupled and internally matched to 100

Ω. Connect a

2:1 balun transformer directly to the RXRF+ (pin 4) and

RXRF- (pin 5) ports to convert the differential 100

input impedance to a single-ended 50

Ω input. Provide

electrically symmetrical input traces from the LNA input

to the balun to maintain IP2 performance and RF com-

mon-mode noise rejection.

LNA Gain Control

The LNA has three gain modes: max gain, max gain -

16dB, and max gain - 33dB. The three LNA gain modes

can be serially programmed through the SPI™ interface

by programming bits D6:D5 in Register 11 (A3:A0 =

1011) or programmed in parallel through the digital

logic gain-control pins, B7 (pin 6) and B6 (pin 3). Set

bit D12 = 1 in Register 8 (A3:A0 = 1000) to enable pro-

gramming through the SPI interface, or set bit D12 = 0

to enable parallel programming. See Table 1 for LNA

gain-control settings.

Pin Description (continued)

NAME

FUNCTION

RXBBQ-

RXBBQ+

Receiver Baseband Q-Channel Differential Outputs. In TX calibration mode, these pins are the LO

leakage and sideband detector outputs.

RXBBI-

RXBBI+

Receiver Baseband I-Channel Differential Outputs. In TX calibration mode, these pins are the LO

leakage and sideband detector outputs.

VCCRXVGA

Receiver VGA Supply Voltage

RXHP

Receiver Baseband AC-Coupling High-Pass Corner Frequency Control Logic Input

VCCRXFL

Receiver Baseband Filter Supply Voltage

TXBBQ-

TXBBQ+

Transmitter Baseband I-Channel Differential Inputs

TXBBI-

TXBBI+

Transmitter Baseband Q-Channel Differential Inputs

VCCRXMX

Receiver Downconverters Supply Voltage

GNDTEST

Connect to Ground

RXTX

RX/TX Mode Control Logic Input. See Table 31 for operating modes.

Exposed Paddle. Connect to the ground plane with multiple vias for proper operation and heat

Table 1. LNA Gain-Control Settings (Pins

B7:B6 or Register A3:A0 = 1011, D6:D5)

B7 OR D6

B6 OR D5

NAME

DESCRIPTION

High

Max gain

Medium

Max gain - 16dB (typ)

Low

Max gain - 33dB (typ)

SPI is a trademark of Motorola, Inc.

MAX2832 Datasheet(PDF) 21 Page - Maxim Integrated Products

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