Silicon Microphone Pre-amplifier Design

A pre-amplifier of Si-microphone is developed in this thesis. The history and the status of the microphones will be introduced before the design of pre-amplifier of Si-microphone, and meanwhile the principle and characteristic of the ECM which is mostly used at present are particularly described. Then the Si-microphone which is very popular today will be brought out. The basic principle, structure and acoustic & electrical performance of MEMS (Micro Electro Mechanical Systems) microphone are studied. The application and market prospect of MEMS microphones using in the IT products are presented briefly too.The pre-amplifier of Si-microphone is designed and manufactured in 0.35μm CMOS mixed technology with supply voltage of 2.2V and on-chip clock at 0.5MHz. The performance of the circuit which is simulated can satisfy the specification. The ASIC has passed the wafer test and the standard test in a microphone module. It has been verified by the customer too.The main contributions of this thesis can be concluded as following:By changing the structure of the band-gap, some unacceptable effects of reference voltage under the control of the changing temperature has been removed.The capacitors of the charge pump circuit with the structure of M3IM2IM1IP have been changed into the structure of PIP, and then it can reduce the effect of the parasitic capacitance and improve the efficiency of the charge pump circuit.When a lot of persons think that it is difficult to make the input capacitance less than 50fF, this thesis proves that an appropriate 0.35μm CMOS mix process can realize the request of the input capacitance.