A 1.1-V 270-/spl mu/A mixed-signal hearing aid chip

Abstract

This paper presents a single-chip mixed-signal IC for a hearing aid system. The IC consumes 270 /spl mu/A of supply current at a 1.1-V battery voltage. The presented circuit and architectural design techniques reduce the total IC power to 297 /spl mu/W, a level where up to 70 days of lifetime is achieved at 10 h/day for a small zinc-air battery. The measured input referred noise for the entire channel is 2.8 /spl mu/Vrms and the average THD in the nominal operating region is 0.02%. The jitter for the on-board ring oscillator is 147 ps rms. The chip area is 12 mm/sup 2/ in a 0.6-/spl mu/m 3.3-V mixed-signal CMOS process.