LT5503

Features:

Single 1.8V to 5.25V Supply
Direct IQ Modulator with Integrated 90° PhaseShifter*
120MHz Modulation Bandwidth
Independent Double-Balanced Mixer
Modulation Accuracy Insensitive to Carrier InputPower
 Modulator I/Q Inputs Internally Biased

Application

  IEEE 802.11 DSSS and FHSS
  High Speed Wireless LAN (WLAN)
  Wireless Local Loop (WLL)
 PCS Wireless Data MMDS


Pinout




Specifications

Supply Voltage ...................................................... 5.5V
Control Voltages .......................... 0.3V to (VCC + 0.3V)
Baseband Voltages (BI+ to BI and BQ+ to BQ) ...... ±2V
Baseband Common Mode Voltage .....1V to (VCC  0.3V)
LO1 Input Power .................................................. 4dBm
LO2 Input Power .................................................. 4dBm
MODIN Input Power ............................................. 4dBm
Operating Temperature Range .................40°C to 85°C
Storage Temperature Range ..................65°C to 150°C
Lead Temperature (Soldering, 10 sec).................. 300°C

Description

The LT®5503 is a front-end transmitter IC designed for low
voltage operation, and is compatible with the LTC family ofWLAN products. The IC contains a high frequency quadrature modulator with a variable gain amplifier (VGA) and a balanced mixer. The modulator includes a precision 90° phase shifter which allows direct modulation of an RF signal by the baseband I and Q signals.

In a superheterodyne system, the mixer can be used to generate the high-frequency RF input for the modulator by mixing the system's 1st and 2nd local oscillators. The LT5503 modulator output delivers 3dBm at 2.5GHz. The VGA allows output power reduction in three steps up to 13dB with digital control. The baseband inputs are
internally biased for maximum input voltage swing at low supply voltage. If needed, they can be driven with external
bias voltages.