1

HFA3724

400MHz Quadrature IF

Modulator/Demodulator

The Intersil 2.4GHz PRISM™ chip set is a

highly integrated five-chip solution for RF

modems employing Direct Sequence

Spread Spectrum (DSSS) signaling. The

HFA3724 400MHz Quadrature IF

Modulator/Demodulator is one of the five chips in the PRISM™

chip set (see the Typical Application Diagram).

The HFA3724 is a highly integrated baseband converter for

quadrature modulation applications. It features all the necessary

blocks for baseband modulation and demodulation of I and Q

signals. It has a two stage integrated limiting IF amplifier with 84db

of gain with a built in Receive Signal Strength Indicator (RSSI).

Baseband antialiasing and shaping filters are integrated in the

design. Four filter bandwidths are programmable via a two bit

digital control interface. In addition, these filters are continuously

tunable over a

±20% frequency range via one external resistor. The

modulator channel receives digital I and Q data for processing. To

achieve broadband operation, the Local Oscillator frequency input

is required to be twice the desired frequency of

modulation/demodulation. A selectable buffered divide by 2 LO

output and a stable reference voltage are provided for convenience

of the user. The device is housed in a thin 80 lead TQFP package

well suited for PCMCIA board applications.

Features

• Integrates all IF Transmit and Receive Functions

• Broad Frequency Range . . . . . . . . . . . 10MHz to 400MHz

• 5th Order Programmable

Low Pass Filter. . . . . . . . . . . . . . . . . . . 2.2MHz - 17.6MHz

• 400MHz Limiting IF Gain Strip with RSSI. . . . . . . . . .84dB

• Low LO Drive Level . . . . . . . . . . . . . . . . . . . . . . . -15dBm

• Fast Transmit-Receive Switching . . . . . . . . . . . . . . . . . 1

µs

• Power Management/Standby Mode

• Single Supply 2.7V to 5.5V Operation

Applications

• Systems Targeting IEEE 802.11 Standard

• TDD Quadrature-Modulated Communication Systems

• Wireless Local Area Networks

• PCMCIA Wireless Transceivers

• ISM Systems

• TDMA Packet Protocol Radios

• PCS/Wireless PBX

• Wireless Local Loop

Simplified Block Diagram

Ordering Information

PART NUMBER

TEMP. RANGE

PACKAGE

PKG. NO.

HFA3724IN

-40 to 85

80 Ld TQFP

Q80.14x14

HFA3724IN96

-40 to 85

Tape and Reel

™

LIM1_IN

MOD_LO_IN

MOD_TX_IF_OUT

LPF_RXQ _OUT

RSSI2

MOD_LO_OUT

RSSI1

÷2

LPF_TXI_IN

LPF_TXQ_IN

2V

REF

LPF_RXI_OUT

I

Q

LO_GND

IF

IF

∑

M

U

X

M

U

X

Data Sheet

November 1999

File Number

4067.7

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 Corporation. PRISM logo is a trademark of Intersil Corporation.