Silicon micromachined condenser microphone array for bionic ears

A miniature condenser microphone array that combines array signal processing and micro-electro-mechanical systems technologies is developed for bionic ears. Electro-acoustical analogy is employed to establish a linear dynamic model of the silicon microphone, while a quasi-static analysis based on the finite difference method is conducted to find the collapse condition. The array configuration serves two purposes: enhancement of the sensitivity and directivity of the transducer. A least square beamforming design based on the template resulting from the multiple signals classification algorithm is proposed to achieve a highly directive beam pattern. To minimize the parasitic effects on the MEMS device, a system-on-chip design is proposed in the paper. The design is composed of a microphone module, a bias circuit, an impedance matching circuit, an on-chip amplifier and array beamforming filter. The performance of the proposed design is evaluated in the frequency response through numerical simulations and the results are discussed.