HFA3724

Features:

• Integrates all IF Transmit and Receive Functions
• Broad Frequency Range . . . . . . . . . . . 10MHz to 400MHz
• I/Q Amplitude and Phase Balance . . . . . . . . . . . 0.2dB, 2o
• 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 . . . . . . . . . . . . . . . . . 1µs
• Power Management/Standby Mode
• Single Supply 2.7V to 5.5V Operation


Application

• 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


Pinout




Specifications

Supply Voltage . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . -0.3V to +6.0V
Voltage on Any Other Pin. . . . . . . . . . . . . . . . . . -0.3V to V_CC +0.3V


Description

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 HFA3724 is housed in a thin 80 lead TQFP package well suited for PCMCIA board applications.