CML - Digital Voice - CMX7262

The CMX7262 Professional Radio Vocoder IC is a device supporting Tri-Wave Excited Linear Prediction (TWELP) vocoder in a single chip.

TWELP is the latest state-of-the-art vocoder technology providing the highest quality natural sounding voice and good reproduction of non-voiced signals such as: police, fire and ambulance sirens. TWELP is also extremely tolerant to acoustic noise and includes an advanced noise reduction system to suppress background noise and includes a decoder side noise gate. The robust FEC algorithm acts on individual vocoder frames for minimum latency and provides optimal performance mitigating bit errors inherent over narrowband radio channels. Modem soft decision bits are also supported to further maximise performance. Input and output signals may be passed through the C-BUS interface or the on-chip analogue-to-digital and digital-to-analogue converters (ADC/DAC).

The device utilises CML’s proprietary FirmASIC component technology. On-chip sub-systems are configured by a Function Image data file that is uploaded during device initialisation and that defines the device's function and feature set. The Function Image can be loaded automatically from a host µC over the C-BUS serial interface or from an external memory device. The device's functions and features can be enhanced by subsequent Function Image releases, facilitating in-the-field upgrades. The CMX7262 operates from a 3.0V to 3.6V supply and includes selectable power saving modes. It is available in a 64-VQFN (Q1) and 64-LQFP (L9) packages.

Block Diagram


  • Half-duplex Operation
  • FEC Built-in
  • Noise Reduction
  • No External DSP or Codecs Required
  • Choice of Signal Input/Out Sources
  • No royalty/license fee
  • C-BUS Host Serial Interface
    • SPI-like with Register Addressing
    • Streaming Input/Output Registers, Low Host Latency
    • C-BUS/Host, PCM Codec, Analogue Audio Output
  • Auxiliary Functions
    • GPIOs
    • Analogue Input/Output Multiplexer
  • Low Power 3.3V Operation with Powersave Functions
  • Small 64-pin VQFN and 64-LQFP (L9) Packages


  • Digital Radio Systems
  • Personal Area Networks
  • Secure Digital Voice Comms
  • Wireless PBX
  • VoIP Applications
  • Digital Software Defined Radio (SDR)

Supply Requirement:

  • 3.0 to 3.6 V