Recent technology advances in thin film deposition and in etching of Si microstructures have made possible the fabrication of a new class of integrated sensors having electronics and sensing element on the same chip. The present paper describes a fully integrated acoustic sensor that combines high sensitivity, wide frequency range and low cost of batch processed miniature silicon components. A sputtered piezoelectric ZnO layer transforms the mechanical deflection of a thin etched Si diaphragm into a piezoelectric charge. This signal is directly connected to the gate of an MOS buffer amplifier through buried contacts. A unique annular electrode design provides cancellation of the temperature-induced parasitic signal due to the pyroelectric effect in ZnO. It also enables connections to be made at the Si/ZnO interface, avoiding step coverage problems and increases the sensitivity by a factor of two over a simple circular electrode design. Integrated devices were fabricated and tested. Measured performances for a 3 mm diameter, 30 μm thick diaphragm were: sensitivity of 25 μV/μbar, a signal-to-noise ratio of 5:1 at 2 μbar, a frequency response of 0.1 Hz to 10 kHz with a 10 10 Ω shunt resistor and a power consumption below 40 microwatts.