A single battery, 0.9 V operated digital sound processing IC including AD/DA and IR receiver with 2 mW power consumption

The sound processing on this chip is done digitally by a programmable DSP processor. The sound processing algorithms are stored in an on-chip RAM. A new algorithm can be downloaded into the RAM through an infrared (IR) remote control. The onboard A/D and D/A converter and IR receiver make this chip a complete stand alone system, needing only a battery, a microphone and/or telecoil, an earphone, an IR diode and few external components. Applications are in hearing instruments and related products. The chip is supplied by a single 1.3V battery, runs at 1MHz clock frequency and consumes only 2mW in full functional mode. The audio sample rate is 16kHz. The dynamic ranges of the A/D and D/A converter (including digital filters, noise shaper and output amplifiers) are 80dBA and 93dBA respectively. The THD of the overall signal path is better than -45dB. The chip is manufactured in a standard low-threshold 0.8/spl mu/m CMOS process.