Designing programmable hearing aids using BiCMOS

BiCMOS is used for digitally programmable hearing aids. The analog signal processing function is implemented with bipolar circuits to provide amplification, automatic gain control (AGC), and filtering in the time-continuous domain, while digital logic and memory are implemented using standard cell CMOS. With on-chip chrome-silicon resistors and poly-to-p/sup +/ capacitors, a 17.8-mm/sup 2/ chip has been designed that includes long time-constant integrators.<
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