Self powered audio compressor circuit

摘要

The application relates to a compressor circuit for a listening device, the compressor circuit comprising a pair of input terminals and a pair of output terminals, the compressor circuit being adapted for receiving an electric input signal representing an audio signal with an input voltage swing Vipp at the input terminals and for providing a possibly compressed version of the input signal as an output signal with an output voltage swing Vopp at the output terminals, the compressor circuit comprising. The application further relates to a listening device and to the use of the compressor circuit. The object of the present application is to provide a compressor circuit with a proper functioning also at relatively low input levels. The problem is solved in that an AC to DC voltage converter for generating a DC-control voltage based on the electric input signal or an AC signal derived therefrom, and a voltage controlled resistance for providing an output voltage swing Vopp controlled by the DC-control voltage, wherein the compressor circuit is energized by the electric input signal. An advantage thereof is that a compressor circuit facilitating a flexible adjustment of the maximum output level is provided. The invention may e.g. be used in portable and non-powered listening devices, e.g. headsets or active ear protection devices.

主权项

1. A compressor circuit for a listening device, the compressor circuit comprising:
a pair of input terminals; and a pair of output terminals, wherein the compressor circuit is configured
to receive an electric input signal representing an audio signal with an input voltage swing Vipp at the input terminals andto provide a possibly compressed version of the input signal as an output signal with an output voltage swing Vopp at the output terminals, and the compressor circuit further comprises
an AC to DC voltage converter for generating a DC-control voltage based on the electric input signal or an AC signal derived therefrom; anda voltage controlled resistance for providing the output voltage swing Vopp controlled by the DC-control voltage, wherein the compressor circuit is energized by the electric input signal, and wherein the voltage controlled resistance comprises a first FET transistor and a second FET transistor, each FET transistor including a source terminal, a gate terminal, and a drain terminal, and wherein the source terminal of the first FET transistor is directly electrically connected in series to the source terminal of the second FET transistor.