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RF Quadrature/Low IF Receiver



  • High Performance (100MHz to 1GHz) RF Receiver
  • 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
      Two Selectable IF Outputs (450kHz or 455kHz)
  • IF:
      IF LO Synthesiser
      IF VCO Negative-Resistance Amplifier


  • Analogue, Digital and Multi-mode Radio
  • Software Defined Radio (SDR)
  • Portable, Mobile and Base Station Terminals
  • TETRA and APCO P25: Phase 1 and Phase 2 TDMA
  • Automatic Identification System (AIS) Transponders
  • Constant Envelope and Linear Modulation
  • Compatible with CMX998
  • Narrowband Systems: 25kHz, 12.5kHz and 6.25kHz
  • Wideband Systems:
    (eg.EN 302 561)
  • APCO Project 25:
    ETSI: EN 300 113, EN 301 166, EN 300 220,
    TS 102 361 (DMR)
  • Satellite Communications

Supply Requirement:

  • 3.3V

The CMX992 is a single-chip, high performance, RF receiver IC for analogue and digital radio systems. It operates from 100MHz to 1GHz and its I/Q architecture supports multiple modulation types and bandwidths with a single radio design.

The CMX992 integrates first mixer, Rx demodulators, IF PLL, and IF VCO subsystems that minimise the external circuits needed to implement a complete receiver. User-selected modes suit different application requirements.

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 CMX992 provides differential and single-ended Rx output options and differential amplifiers for flexible signal conditioning.The CMX992 includes the core RF and IF functions of a high performance receiver and can be used in a wide range of narrowband and wideband wireless products including multi-mode analogue/digital terminals.

The CMX992 can be used where highly linear modulations are being used, e.g. for applications such as TETRA, where a typical transmitter solution would include the CMX998 Cartesian Feedback Transmitter.

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

Block Diagram

CMX992 Block Diagram

Design Support Information

CMX991 and CMX992 Operation Below 100MHz This Application Note seeks to provide useful guidance on the use of the devices below 100MHz and contains details of how such operation can be demonstrated through component changes to the matching circuits on the EV9910B and EV9920B Evaluation Kits.
Frequency Estimation for a VCO using a Negative Resistance Amplifier Application Note describing how to estimate the operating frequency of VCO designs using a negative resistance amplifier. An Excel spreadsheet that automates the calculation is available below.
Excel Spreadsheet - Frequency Estimation for a VCO using a Negative Resistance Amplifier An Excel spreadsheet that calculates the operating frequency of VCO designs using a negative resistance amplifier. An Application Note describing the process is available above.
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