AD1843

The AD1843 SoundComm™ Codec is a complete analog front nd for high performance DSP-based telephony and audio applications.The device integrates the real-world analog I/O requirements or many popular functions thereby reducing size,power consumption, and system complexity. The AD1843 oundComm is the world's first codec which can support four ifferent sample rates simultaneously, without any beat frequency oise issues. This is essential for highly integrated audio/modem/fax products since the sample rates associated with audio re very much distinct from the sample rates associated with elephony-oriented data communication. It is also the first codec o offer on-chip digital phase lock loops for sample rate synchronization o external clock signals. This sample rate flexibility is nabled through Analog Devices' Continuous Time Oversampling CTO) technology.

The main elements of the AD1843 are its extensive input and mixing ection, its two channels of sigma-delta () analog-to-digital onversion, its four channels of digital-to-analog conversion, its igital filters, and the clock and control circuitry for implementing he device's different modes. The AD1843 permits flexible samplerate election through programming and external synchronization,many input and output options, and many mixing options.

The versatility of the device is shown by the following examples of functions it can perform:
• Stereo audio input and/or quad output, simultaneously at different sample rates
• Stereo audio output with simultaneous full duplex modem or fax operation with frequency and phase resampling
• Mono audio input and stereo audio output with simultaneous modem receive and transmit for simultaneous voice and data communications
• Dual independent audio inputs with audio output for echocancelling speakerphones