LT5558 - 600MHz to 1100MHz High Linearity Direct Quadrature Modulator


  • Direct Conversion from Baseband to RF
  • High OIP3: + 22.4dBm at 900MHz
  • Low Output Noise Floor at 20MHz Offset:
      No RF: –158dBm/Hz
      POUT = 4dBm: –152.7dBm/Hz
  • Low Carrier Leakage: –43.7dBm at 900MHz
  • High Image Rejection: –49dBc at 900MHz
  • 3 Channel CDMA2000 ACPR: –70.4dBc at 900MHz
  • Integrated LO Buffer and LO Quadrature Phase Generator
  • 50Ω AC-Coupled Single-ended LO and RF Ports
  • High Impedance Interface to Baseband Inputs with 2.1V Common Mode Voltage
  • 16-Lead QFN 4mm × 4mm Package

Typical Application

LT5558 Typical Application
LT5558 Typical Application


The LT5558 is a direct I/Q modulator designed for high performance wireless applications, including wireless infrastructure. It allows direct modulation of an RF signal using differential baseband I and Q signals. It supports GSM, EDGE, CDMA, CDMA2000, and other systems. It may also be confi gured as an image reject upconverting mixer, by applying 90° phase-shifted signals to the I and Q inputs. The high impedance I/Q baseband inputs consist of voltage-to-current converters that in turn drive doublebalanced mixers. The outputs of these mixers are summed and applied to an on-chip RF transformer, which converts the differential mixer signals to a 50Ω single-ended output. The balanced I and Q baseband input ports are intended for DC coupling from a source with a common-mode voltage level of about 2.1V. The LO path consists of an LO buffer with single-ended input, and precision quadrature generators which produce the LO drive for the mixers. The supply voltage range is 4.5V to 5.25V.


CAD Symbols and Footprints: The downloadable Zip file below contains the schematic symbol and PCB footprints.

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

Part Number Package Code Temp Package
LT5558EUF#PBF 4x4 QFN-16 UF E 05-08-1692 Yes
LT5558EUF#TRPBF 4x4 QFN-16 UF E 05-08-1692 Yes

LT5558 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

Package Variations and Pricing

Part Number Package Temp Price
LT5558EUF#PBF 4x4 QFN-16 E $7.60 $5.35 Yes
LT5558EUF#TRPBF 4x4 QFN-16 E $5.40 Yes
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* The USA list pricing shown is for BUDGETARY USE ONLY, shown in United States dollars (FOB USA per unit for the stated volume), and is subject to change. International prices may differ due to local duties, taxes, fees and exchange rates. For volume-specific price or delivery quotes, please contact your local Linear Technology sales office or authorized distributor.

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.

Part Number Description Price Documentation
DC1017A LT5558EUF | 600-1100MHz I-Q Modulator w/ Hi-Z BB Rin, Vcm = 2.1V $125.00
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Click here to view our complete list of demo boards


  • RFID Single-Sideband Transmitters
  • Infrastructure TX for Cellular and ISM Bands
  • Image Reject Up-Converters for Cellular Bands
  • Low-Noise Variable Phase-Shifter for 600MHz to 1100MHz Local Oscillator Signals
  • Microwave Links

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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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