Patent Number: 6,427,015

Title: Power supply for microphone

Abstract: The invention concerns a circuit for the amplification of signals from a microphone, comprising a power source and a current generator which supplies a microphone, such as an electret microphone, with electrical energy in the form of pulses. The circuit clocks the power supply to the microphone with an active pulse time t1, and the sampling circuit reads the microphone signal in a window with the duration t2 calculated from the rear flank of the active part of the supply pulse, whereby t1 is shorter than the time period T corresponding to the sampling frequency 1/T, and whereby t1 is of a length which is sufficient to enable the microphone current to reach a usable value, and whereby t2 can be shorter than t1.

Inventors: Backram; Lars (Saffle, SE), Backram; Hans-Erik (Saffle, SE), Gustafsson; Borje (Svanskog, SE)

Assignee: GN Netcom A/S

International Classification: H04R 3/00 (20060101); H03F 021/00 ()

Expiration Date: 07/30/2010