Single-Chip Codec Raises Voice Quality, Cuts Power Consumption

A mixed-signal codec for CDMA-based wireless handset applications is said to provide designers with greater programming flexibility and ease of design while simultaneously improving system voice quality and reducing power consumption. The TWL1101 voice-band audio processor performs the transmit encoding (A/D conversion) and receive decoding (D/A conversion) for handsets. It also provides transmit and receive filtering for wireless phones and other voice-band communication systems.In addition to supporting CDMA systems, the TWL1101 processor is also compatible with any other application requiring an interface between a human voice and a DSP ormicrocontroller. These applications might include hands-free cellular kits, speaker phones, answering machines, voice modems, digital intercoms, digital PBXs, wireless local-loop handsets, voice interfaces to computers, and voice-actuated security systems.Among the chip's features are sigma-delta conversion technology and digital filtering, which require less power and produce a higher-quality voice signal compared to earlier codecs, it's claimed. Added sidetone produces a more natural-sounding voice from speakers. It also simplifies DSP programming by offloading sidetone algorithms. Further, to simplify system clocking, the chip generates all the necessary clocks itself.All of the new features are fully programmable by means of the chip's I²C bus serial interface, giving designers a significant amount of control.