1

TM

File Number

4860.2

CAUTION: These devices are sensitive to electrostatic discharge; follow proper IC Handling Procedures.

1-888-INTERSIL or 321-724-7143

PRISM® is a registered trademark of Intersil Americas Inc. PRISM and design is a trademark of Intersil Americas Inc.

ISL3685

2.4GHz RF/IF Converter and Synthesizer

The ISL3685 is a monolithic SiGe

half duplex RF/IF transceiver

designed to operate in the 2.4GHz

ISM band. The receive chain features

a low noise, gain selectable amplifier (LNA) followed by a

down-converter mixer. An up-converter mixer and a high

performance preamplifier compose the transmit chain. The

remaining circuitry comprises a high frequency Phase

Locked Loop (PLL) synthesizer with a three wire

programmable interface for local oscillator applications.

A reduced filter count is realized by multiplexing the receive

and transmit IF paths and by sharing a common differential

matching network. Furthermore, both transmit and receive

RF amplifiers can be directly connected to mixers as

bandwidth characteristics attenuate image frequencies. The

inherent image rejection of both the transmit and receive

functions allows this economic advantage.

The ISL3685 is housed in a 44 lead MLFP package well

suited for PCMCIA board and MINI PCI applications.

Simplified Block Diagram

Features

• Highly Integrated

• Multiplexed RX/TX IF Path prescribes Single IF Filter

• Programmable Synthesizer

• Gain Selectable LNA

• Power Management/Standby Mode

• Single Supply 2.7V to 3.3V Operation

Cascaded LNA/Mixer (High Gain)

• Gain . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .25dB

• SSB Noise Figure. . . . . . . . . . . . . . . . . . . . . . . . . . . 3.7dB

• Input IP3 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . -12dBm

• IF Frequency . . . . . . . . . . . . . . . . . . . 280MHz to 600MHz

Cascaded LNA/Mixer (Low Gain)

• Gain . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . -9dB

• Input P1dB . . . . . . . . . . . . . . . . . . . . . . . . . . . . . +2.5dBm

• IF Frequency . . . . . . . . . . . . . . . . . . . 280MHz to 600MHz

Cascaded Mixer/Preamplifier

• Transmit Cascaded Mixer/Preamplifier Gain . . . . . . .25dB

• SSB Noise Figure. . . . . . . . . . . . . . . . . . . . . . . . . . . .10dB

• Output P1dB. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4dBm

• IF Frequency . . . . . . . . . . . . . . . . . . . 280MHz to 600MHz

Applications

• IEEE802.11 1Mbps and 2Mbps Standard

• Systems Targeting IEEE802.11, 11Mbps Standard

• Wireless Local Area Networks

• PCMCIA Wireless Transceivers

• ISM Systems

• TDMA Packet Protocol Radios

• MINI PCI Wireless Transceivers

Ordering Information

PART NUMBER

TEMP RANGE

PACKAGE

PKG. NO

ISL3685IR

-40 to 85

44 Ld MLFP

L44.7x7

ISL3685IR96

-40 to 85

Tape and Reel

RX_MX_OUT

PLL

LO_IN

RX_IN

INTERFACE

TXA_OUT

REF_IN

TX_MX_IN

CP_DO

MODULE

Data Sheet

January 2001