Hearing aid with an H-bridge output stage and a method of driving an output stage

摘要

A digital, three-level output driver (7) of the H-bridge variety for a hearing aid (20) obtains a reduced capacitive interference by providing a primary voltage (3) and a secondary voltage (8) for the output driver (7) and applying the secondary voltage (8) to both sides of the output driver (7) whenever the middle level of the three-level output driver (7) is present in the input signal for the output driver (7). The output driver (7) may be controlled from a pulse-width modulated signal, a sigma-delta pulse-density modulated signal, or a combination of those signals. The output driver (7) produces a clocked output signal consisting of a positive level, a negative level, and a zero level for driving an acoustic output transducer of the hearing aid (20). The invention provides a hearing aid (20) and a method of driving an output stage (7) of a hearing aid (20).

主权项

1. A hearing aid comprising an input transducer, an analog-to-digital converter, a digital signal processor, a three-level output modulator connected to a three-level output driver, a first voltage source providing a first voltage, a second voltage source providing a second voltage different from said first voltage, a common voltage node and an acoustic output transducer, wherein the output driver comprises an H-bridge output stage configured to control the connection of a first and a second terminal of the acoustic output transducer, the H-bridge being configured to connect the first voltage source to the first terminal of the acoustic output transducer and the common voltage node to the second terminal of the acoustic output transducer when the output modulator generates a first level, to connect the second voltage source to both the first and the second terminal of the acoustic output transducer when the output modulator generates a second level, and to connect the first voltage source to the second terminal of the acoustic output transducer and the common voltage node to the first terminal of the acoustic output transducer when the output modulator generates a third level.