Receiver with multiple drive coils

摘要

The invention provides a moving armature receiver, such as for a hearing aid, with at least two drive coils adapted to be driven by separate drive signal across different frequency ranges. This is achieved by a frequency dividing network adapted to split an audio input signal into first and second audio signals of predetermined different frequency ranges. In preferred two drive coil versions the frequency ranges overlap below 2-3 kHz, whether only one of the drive coils is active above 2-3 kHz. The drive coil being active in the upper frequency range has a lower impedance than the other drive coil. Thus, a more suitable effective impedance characteristics can be obtained. This enables an increased maximum acoustic high frequency output and an enhanced high frequency response of the receiver when driven by a low impedance amplifier, such as a class D amplifier. In a preferred embodiment the receiver is adapted to receive a digital audio input signal, the frequency division is performed digitally and two separate digital signals are applied to two separate digital amplifiers each operatively coupled to drive two separate drive coils. The invention also provides a hearing aid output stage adapted to drive a multiple coil moving armature receiver.