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CML IC offers voice codec/processor, audio PA

Posted: 26 Mar 2004 ?? ?Print Version ?Bookmark and Share

Keywords:cmx981? digital radio baseband processor ic? cml?

CML Microcircuits (UK) Ltd has released its latest digital radio baseband processor IC that is an advanced IC combined on-chip with a voice codec/processor and an audio PA.

A low-power device, the CMX981 interfaces the analog and digital sections of a digital radio system and performs many of the radio's DSP-intensive functions. According to the company, its overall functionality within a digital radio application relieves the host processor of a significant amount of processing, allowing for an overall reduction in power consumption.

The CMX981 supports digital fixed, portable and mobile TETRA, APCO 25, Tetrapol and the Japanese RCR and ARIB system applications, and is flexible for use in other digital radio systems. Its default coefficients provide the root raised cosine (RRC) path responses required for TETRA operation.

With the device, integrated functions, smaller processor requirement, less PCB area and components and minimized power consumption will lead to reduced design times and lower project and operational costs.

In its transmit path, the IC offers all the functions required to convert digital 'symbol' data into suitably filtered analog I and Q signals for external up-conversion and transmission. Also available to the Tx function is digital control of output amplitudes and offsets.

CML explains that the CMX981's receive path accepts differential analog baseband I/Q signals, samples them and performs digital channel select filtering to simplify host processing and data extraction. Internal digital offset correction and the digital filters are fully programmable.

The on-chip voice codec can be configured to apply a digital voice filter as required, including the operation to the G.712 specification. Its encode path accepts a differential analog audio input signal, converts it to digital form and applies digital voice filtering to produce a processed digital stream. The decode path accepts a digital stream written to the serial interface, applies digital voice filtering, converts the result to an analog signal and presents the signal at the speaker or single-ended earphone analogue driver outputs. The Rx path also includes a sidetone function and an audio-tone generator.

Available in a 64-lead VQFN package, the CMX981 has a low operating power requirement in the 2.25V to 2.75V range.

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