Patent ID: 6625277
Filing Date: 2003-09-23
Classification: H04M

Abstract:
A low voltage compression circuit interposed in the signal path between a telephone receiver and a telephone headset earphone, comprising:a) an operational amplifier having a pair of input terminals comprising a negative input terminal and a positive input terminal, and an output terminal, the amplifier having the amplification characteristic such that the voltage at the output terminal is determined by the difference between the voltage applied to the positive input terminal and the negative input terminal; the negative input terminal being connected to said telephone receiver, and the output terminal being connected to said telephone headset earphone; b) a reference voltage connected to the positive input terminal of said amplifier; c) a feedback path comprising resistors connected between said output terminal and said negative input terminal; and d) a Schottky diode circuit connected to said output terminal, and a semiconductor switch having a control gate connected to said Schottky diode, said semiconductor switch having a pair of output switched terminals, one output terminal connected to said resistor feedback path and the other output terminal connected to said reference voltage.