High-performance condenser microphone with fully integrated CMOS amplifierand DC-DC voltage converter

The development of a capacitive microphone with an integrated detection cir cuit is described. The condenser microphone is made by micromachining of po lyimide on silicon. Therefore, the structure can be realized by postprocess ing on substrates containing integrated circuits (IC's), independently of t he IC process. Integrated microphones with excellent performances have been realized on a CMOS substrate containing dc-dc voltage converters and pream plifiers. The measured sensitivity of the integrated condenser microphone w as 10 mV/Pa, and the equivalent noise level (ENL) was 27 dB(A) re, 20 mu Pa for a power supply voltage of 1.9 V, which was measured with no bias volta ge applied to the microphone. Furthermore, a back chamber of infinite volum e was used in all reported measurements and simulations. [338].