Hearing aid amplifier circuitry
US5745587A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Jun 7, 1995 |
| Grant date | Apr 28, 1998 |
| Priority date | — |
| Expiry date | Jun 7, 2015 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04R25/502
- WIPO fieldBasic communication processes
- WIPO sectorElectrical engineering
Abstract
An electroacoustic device such as a hearing aid having a battery, microphone, speaker, a preamplifier, a voltage regulator and power amplifier. The power amplifier includes identically configured output and bridge stages connected to opposite sides of the speaker, the output signals from the output stage being connected through a blocking capacitor to the input of the bridge stage. The output/bridge stage circuit includes an interface stage and two current gain stages. The interface stage converts voltage signals to current signals with a pair of outputs respectively connected to the two like-configured current gain stages. Each current gain stage includes two successive sections, each having a pair of transistors, one of which is configured as a diode connected in series with a resistor to shunt current from the base of the other transistor. The current output of the current gain stages is thus responsive to the input current level, permitting low quiescent current with efficient delivery of current to the receiver, and providing high peak currents with minimum distortion. Also, quiescent current is essentially insensitive to variations in battery voltage and temperature.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.