SS0105A – CMOS audio amplifier for hearing aids

SS0105A – CMOS audio amplifier for hearing aids


The SS0105A is an audio amplifier composed of a variable gain preamp and a power amplifier capable of delivering 15 mW of peak output power to a differential loudspeaker (balanced loudspeaker) with nominal impedance down to 70 ohm.

The amplifier is tailored for medical hearing aid, being able to supply miniature electret condenser microphones and to drive miniature magnetic balanced receivers from a single zinc-air battery.

SS0105A proofs excellent sound quality and low distortion operation over large supply range for long lifetime application.

Capacitors charge transients causing typical annoying click/pop at the startup are not audible thanks to the clickless/popless feature of the SS0105A.

The circuit is designed for chip-on-board direct mounting but packaging can be organized on demand (24 lead 4X4 QFN).

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  • Very low voltage 1 – 1.6 V DC supply
  • Internal voltage regulator
  • Microphone supply 0.9 V
  • Class AB operation
  • Open drain push-pull output stage
  • Differential loudspeaker, 70 ohm min
  • THD < 1 %
  • 15 mW output power @ 10% THD
  • Low quiescent current
  • Soft startup for popless/clickless operation
  • CMOS technology
  • Die size 1220 um x 1220 um
  • Naked die for space saving chip-on-board mounting
  • 24 lead 4X4 QFN package available on demand


  • Medical hearing aid audio amplifier
  • Portable audio systems
  • Designed to be a replacement chip of the Gennum’s LV549 (amplifier) + LC506 (pre-amplifier) embedding the functionality of two chips (pre-amplifier + power amplifier) in a single die




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