The application of double-gate MOSFET mixer in digital pressure sensor

A digital pressure sensor using a double-gate MOSFET mixer is presented. The sensitive unit of this pressure sensor is comprised of MOS ring oscillators. The syntonic frequency of the ring oscillators will change according to the stress caused by pressure due to the MOSFET piezoresistive effect. The double-gate MOSFET mixer is used as an internal signal processor in order to improve the characteristics of the output signal. The pressure sensor has many good characteristics such as high sensitivity, low temperature coefficient and simple fabrication process. The device was fabricated by a standard IC process mixed with a MEMS process. The sensitivity of fabricated devices is 1.52 kHz/kPa. The temperature shift of zero output is -0.5% FS.