The AD1803/AD1804 chipset allows the implementation of a low-cost full Modem DAA Line Interface and codec with minimal external components. The AD1803 can also be used as a stand-alone codec for voice/handset/telephony applications, or as a cellular telephone interface. The AD1803 is an Intel AC'97 Rev 2.1-compliant modem codec (refer to Intel's AC'97 specifications at www.intel.com) with selectable AC'97 or a DSP-style serial interface. The AD1803 codec uses high-performance sigma-delta ADC and DACs with programmable gain/attenuation. It has a digital monitor output with selectable mix from ADC and DAC channels for call progress monitoring. The AD1803 supports ring validation and wake-up interrupt output signalling. The AD1803 has programmable filters dedicated to impedance synthesis and when used with the AD1804, it provides a complete digital line termination impedance synthesis control loop. The AD1804 is a solid-state line-side analog phone interface device that replaces a conventional discrete DAA. The AD1804 eliminates the need for transformer, relays, opto-isolators and a 2-to-4-wire hybrid. The AD1804 uses high-performance sigmadelta ADC and DACs with programmable gain/attenuation. It has digitally selectable line termination impedances.