A CMOS pressure sensor with integrated interface for passive RFID applications

This paper presents a CMOS pressure sensor with integrated interface for passive RFID sensing applications. The pressure sensor consists of three parts: top electrode, dielectric layer and bottom electrode. The dielectric layer consists of silicon oxide and an air gap. The bottom electrode is made of polysilicon. The gap is formed by sacrificial layer release and the Al vapor process is used to seal the gap and form the top electrode. The sensor interface is based on phase-locked architecture, which allows the use of fully digital blocks. The proposed pressure sensor and interface is fabricated in a 0.18 mu m CMOS process. The measurement results show the pressure sensor achieves excellent linearity with a sensitivity of 1.2 fF kPa(-1). The sensor interface consumes only 1.1 mu W of power at 0.5 V voltage supply, which is at least an order of magnitude better than state-of-the-art designs.