Microphone component and method for operating same

摘要

A system and method are described for reducing the current consumption of a microphone component without adversely affecting performance. The system includes a micromechanical microphone capacitor, an acoustically inactive compensation capacitor, an arrangement for applying a high-frequency sampling signal to the microphone capacitor and for applying the inverted sampling signal to the compensation capacitor, an integrating operational amplifier which integrates the sum of the current flow through the microphone capacitor and the current flow through the compensation capacitor as a charge amplifier, a demodulator, which is synchronized with the sampling signal, for the output signal of the integrating operational amplifier, and a low-pass filter which uses the output signal of the demodulator to obtain a microphone signal that corresponds to the changes in capacitance of the microphone capacitor. The sampling signal is composed of a periodic sequence of sampling pulses and pause times. In addition, at least one first switching element is provided which reduces the current flow through the integrating operational amplifier during the pause times. The low-pass filter has a “sample-and-hold” characteristic so that during the pause times the low-pass filter in each case stores the output signal of the integrating operational amplifier averaged over the preceding sampling operation.

主权项

1. A microphone component, comprising:
a micromechanical microphone capacitor; an acoustically inactive compensation capacitor; a sampling signal arrangement to apply a high-frequency sampling signal to the microphone capacitor and to apply an inverted sampling signal to the compensation capacitor; an integrating operational amplifier which integrates a sum of a current flow through the microphone capacitor and a current flow through the compensation capacitor; a demodulator, which is synchronized with the sampling signal, for the output signal of the integrating operational amplifier; and a low-pass filter for obtaining a microphone signal, which corresponds to the changes in capacitance of the microphone capacitor, from the output signal of the demodulator; wherein the sampling signal is composed of a periodic sequence of sampling pulses and pause times, wherein at least one first switching element reduces the current flow through the integrating operational amplifier during the pause times, and wherein the low-pass filter has a “sample-and-hold” characteristic so that during the pause times the low-pass filter in each case stores the output signal of the integrating operational amplifier averaged over the preceding sampling operation.