CML - Radio Frequency - CMX991

The CMX991 is a single-chip, high performance, low cost RF transceiver that provides the core functions required to implement a full-featured radio transmitter and receiver.
It operates from 100MHz to 1GHz and its I/Q architecture supports multiple modulation types and bandwidths with a single radio design.

The half-duplex CMX991 integrates Tx modulators, Rx demodulators, IF PLL and IF VCO subsystems to minimise the external circuits needed when implementing a complete RF transceiver chip.

User-selected modes suit different application requirements.

The Tx path includes an I/Q modulator to accurately generate modulation at the IF frequency, which may then be translated to the final RF frequency by an integrated image-reject up-converter system.The I/Q modulator IF output is also made available for conversion to RF via external circuits, if desired.

The Rx path includes an integrated 1st Rx mixer having two outputs to support two external 1st IF filter choices, then an integrated 2:1 input MUX followed by VGA and wideband signal level measurement functions, to support AGC implementation.

The 1st IF signal is then either I/Q demodulated to Zero-IF or mixed to a Low IF output.

The CMX991 provides differential and single-ended Rx output options and differential amplifiers for flexible signal conditioning.

An application note is available below that facilitates operation of the CMX991 RF Transceiver below 100MHz.


  • High Performance (100MHz to 1GHz) RF Transceiver
  • Half-duplex Operation
  • Rx:
    •   RF Mixer with Output Select
    •   1st IF Input Select
    •   1st IF Variable Gain Amplifier (VGA)
    •   1st IF Signal Level Indicator (SLI)
    •   Two-mode Demodulator
    •   I/Q Zero IF with Diferential Outputs
    •   Selectable IF Outputs (450kHz or 455kHz)
  • Tx:
    •   I/Q Modulator to IF
    •   Image-reject Up-converter
    •   IF and RF Outputs
  • IF:
    •   IF LO Synthesiser
    •   IF VCO Negative-Resistance Amplifier


  • Analogue, Digital and Multimode Radio
  • Software Defined Radio (SDR)
  • Portable, Mobile and Base Station Terminals
  • Data Telemetry Modems
  • ETSI:
    •   EN 300 113, EN 301 166, EN 302 561, EN 300 220, TS 102 361 (DMR)
  • APCO Project 25: Phase 1 and Phase 2 TDMA:
    • TIA-102.CAAB
  • Automatic Identification System (AIS) Transponders
  • Constant Envelope and Linear Modulation
  • Narrowband Systems: eg. 25kHz, 12.5kHz and 6.25kHz
  • Wideband Systems: eg. up to 2MHz
  • Satellite Communications

Supply Requirement:

  • 3.3V