Hearing aid amplifier circuitry
First Claim
1. A power amplifier comprising:
- a. an interface stage having a first pair of current gain devices, each having a base connected to receive incoming voltage signals, and respective first and second outputs for current signals to which said voltage signals are converted by said interface stage;
b. a first current gain stage having a first input connected to receive said current signals from said first output, a third output connected to a load, and a first variable gain means connected between said first input and said third output for increasing current gain in response to increases in said current signals; and
c. a second current gain stage having a second input connected to receive said current signals from said second output, a fourth output connected to said load, and second variable gain means connected between said second input and said fourth output for increasing current gain in response to increases in said current signals.
4 Assignments
0 Petitions
Accused Products
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.
46 Citations
26 Claims
-
1. A power amplifier comprising:
-
a. an interface stage having a first pair of current gain devices, each having a base connected to receive incoming voltage signals, and respective first and second outputs for current signals to which said voltage signals are converted by said interface stage; b. a first current gain stage having a first input connected to receive said current signals from said first output, a third output connected to a load, and a first variable gain means connected between said first input and said third output for increasing current gain in response to increases in said current signals; and c. a second current gain stage having a second input connected to receive said current signals from said second output, a fourth output connected to said load, and second variable gain means connected between said second input and said fourth output for increasing current gain in response to increases in said current signals. - View Dependent Claims (2, 3, 4, 5)
-
-
6. In a sound amplification device comprising a battery, a means for receiving audible sounds and converting them to voltage signals, a power amplifier, and a speaker for receiving amplified voltage signals and converting them to audible sounds;
- the improvement which comprises using a power amplifier comprising;
a. an interface stage having a first pair of current gain devices, each having a base connected to receive incoming voltage signals, and respective first and second outputs for current signals to which said voltage signals are converted by said interface stage; b. a first current gain stage having a first input connected to receive said current signals from said first output, a third output connected to the speaker, and a first variable gain means connected between said first input and said third output for increasing current gain in response to increases in said current signals; and c. a second current gain stage having a second input connected to receive said current signals from said second output, a fourth output connected to the speaker, and second variable gain means connected between said second input and said fourth output for increasing current gain in response to increases in said current signals. - View Dependent Claims (7, 8, 9, 10)
- the improvement which comprises using a power amplifier comprising;
- 11. A power gain configuration comprising two essentially identically configured power amplifiers having respective outputs connected across a load, the first power amplifier having an input connected to receive incoming voltage signals and the second power amplifier having an input connected to the output of the first power amplifier, each of the power amplifiers including means for effecting gain of current signals which increases in response to increases in the level of the current signals.
-
18. In a sound amplification device comprising a battery, a means for receiving audible sounds and converting them to voltage signals, a power gain configuration, and a speaker for receiving amplified voltage signals and converting them to audible sounds;
- the improvement which comprises using a power gain configuration comprising two essentially identically configured power amplifiers having respective outputs connected across the speaker, the first power amplifier having an input connected to receive incoming voltage signals and the second power amplifier having an input connected to the output of the first power amplifier, each of the power amplifiers including means for effecting gain of current signals which increases in response to increases in the level of the current signals.
- View Dependent Claims (19, 20, 21, 22, 23, 24)
Specification