Microphone circuit

Abstract

The invention provides a microphone circuit. In one embodiment, the microphone circuit comprises a microphone, a self-biased amplifier with a finite gain, and a feedback capacitor. The microphone coupled between a ground and a first node generates a first voltage at the first node according to sound pressure. The self-biased amplifier has a positive input terminal coupled to the ground and a negative input terminal coupled to the first node and amplifies the first voltage according to the finite gain to generate a second voltage at a second node. The feedback capacitor coupled between the first node and the second node feeds back the second voltage to the first node. The second voltage is then output to a following module subsequent to the microphone circuit.

Description

technical field [0001] The present invention relates to microphones, and more particularly to microphone circuits. Background technique [0002] FIG. 1A is a block diagram of a conventional microphone circuit 100 . The microphone circuit 100 includes a microphone 102 , an electrostatic discharge protection circuit 104 , and a follow-up circuit 108 . Microphone 102 detects external sound waves and converts the sound waves into a voltage signal V o , the voltage signal V o It is output to the subsequent circuit 108 at node 131 . In one embodiment, the subsequent circuit 108 is a clamp amplifier or an analog-to-digital converter. The ESD protection circuit 104 includes two diodes 112 and 114 connected in opposite phase, and clamps the voltage signal V o The range of is within a certain limit, so as to protect the subsequent circuit 108 from the impact of electrostatic discharge. [0003] Microphone 102 includes two conductive plates, which form a capacitance value C m of...

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Problems solved by technology

However, 1Ω resistors occupy a large chip area and are difficult to manufacture in semiconductor processes

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