Low voltage programmable compressor
First Claim
1. An improved low voltage compressor or expander adapted for implementation on an integrated circuit comprising:
- (a) input means for inputting an audio signal;
(b) output means for outputting a processed audio signal;
(c) variolosser means having first and second control terminals, an input terminal coupled to said inputting means and an output terminal coupled to said outputting means, said variolosser further including means for generating said processed audio signal in a predetermined gain relationship with respect to said audio signal wherein the gain relationship of said audio signal and said processed audio signal is controlled by the ratio of the currents flowing in said first and second control terminals; and
(d) control circuit means coupled to said variolosser means for independently controlling the current flowing in each of said first and second control terminals of said variolosser means wherein the ratio of said currents is controlled based on a predetermined relationship between said audio signal and said current flowing in each of said first and second control terminals.
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Accused Products
Abstract
A programmable low voltage compressor circuit suitable for use with hearing aids is described. The compressor has a continuously variable compression ratio wherein the gain of the compressor may be programmably controlled over a wide range and the compressor may be powered from a power source as low as 1.1 volt. The compressor employs a variolosser wherein the gain is controlled by the ratio of the currents flowing out of first and second control terminals. A control circuit coupled to the variolosser controls the magnitude of the currents flowing out of the two control terminals. The control circuit includes a peak detector which generates a signal related to the peak positive envelope of the signal input to the compressor. A voltage to current converter is coupled to the peak detector for increasing the magnitude of the current flowing out of one of the control terminals of the variolosser as the voltage output of the peak detector increases. Furthermore, the gain and compression ratio of the compressor over a wide range is programmably controllable.
25 Citations
13 Claims
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1. An improved low voltage compressor or expander adapted for implementation on an integrated circuit comprising:
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(a) input means for inputting an audio signal; (b) output means for outputting a processed audio signal; (c) variolosser means having first and second control terminals, an input terminal coupled to said inputting means and an output terminal coupled to said outputting means, said variolosser further including means for generating said processed audio signal in a predetermined gain relationship with respect to said audio signal wherein the gain relationship of said audio signal and said processed audio signal is controlled by the ratio of the currents flowing in said first and second control terminals; and (d) control circuit means coupled to said variolosser means for independently controlling the current flowing in each of said first and second control terminals of said variolosser means wherein the ratio of said currents is controlled based on a predetermined relationship between said audio signal and said current flowing in each of said first and second control terminals. - View Dependent Claims (2, 3, 4, 5, 6, 8, 9, 10, 11, 12, 13)
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7. The apparatus of claim wherein said detector means includes means for limiting the maximum output signal of said detector means.
Specification