Abstract: An improved analog hearing aid is provided which incorporates a current source transconductance amplifier as an input stage. The gain defining bias current of the input stage transconductance amplifier is adjusted upon the application of battery power to the hearing aid to define a low input signal gain, and is then reduced by two gain regulators to define a compression threshold and compression ratio, and to provide a maximum output ceiling. Also provided is a method of trimming the low signal gain of the hearing aid at the time battery power is applied.

Abstract: An improved hearing aid amplifier circuit employs a Class D amplifier which includes an output to input feedback loop to minimize distortion, stabilize gain, and simplify the design requirements for several circuit elements of the Class D amplifier.