LT5503 - 1.2GHz to 2.7GHz Direct IQ Modulator and Mixer


  • Obsolete - Contact Factory For Replacement
  • Single 1.8V to 5.25V Supply
  • Direct IQ Modulator with Integrated 90° Phase Shifter*
  • Four Step RF Power Control
  • 120MHz Modulation Bandwidth
  • Independent Double-Balanced Mixer
  • Modulation Accuracy Insensitive to Carrier Input Power
  • Modulator I/Q Inputs Internally Biased
  • Available in 20-Lead FE Package

Typical Application

LT5503 Typical Application
LT5503 Typical Application


The LT5503 is a front-end transmitter IC designed for low voltage operation. 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 P 1dB is –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.


For complete and up to date package information and drawings, please refer to our packaging page

LT5503 Package Drawing

Order Info

  • Part numbers ending in PBF are lead free. Solder plated terminal finish (SnPb) versions are non-standard and special terms and conditions and pricing applies if available. Please contact LTC marketing for information.
  • Part numbers containing TR or TRM are shipped in tape and reel or 500 unit mini tape and reel, respectively
  • Please refer to our general ordering information or the product datasheet for more details

Demo Boards

Linear Technology offers many demo boards free of charge to qualified customers. Contact your local sales office or distributor to inquire about a demo board. Certain demo boards are also available for sale via credit card on this website. Demo boards are for evaluation purposes only. It remains the customer’s responsibility to verify proper and reliable operation in the actual end application.

Click here to view our complete list of demo boards


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

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Design Tools

Linear Technology provides a variety of custom design simulation tools and device models to allow even novice designers to quickly and easily evaluate circuits using high performance switching regulators, amplifiers, data converters, filters and more. Please visit our Design Tools page to view and download:

  • LTspice - A powerful SPICE simulator, schematic capture and waveform viewer with enhancements and models for easing the simulation of switching regulators
  • LTpowerCAD - A complete power supply selection, synthesis and design tool
  • LTpowerPlay - A development environment supporting Linear Technology's Digital Power System Management (PSM) products
  • PScope & QuikEval - USB-based product demonstration and data acquisition system for use with our ADCs, DACs, and more
  • Linduino - Arduino compatible system for developing and distributing firmware libraries and example code
  • LinearLab Tools - A collection of Matlab and Python programs that provide direct access to Linear Technology’s data converter evaluation boards
  • And More!

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