Capacitive sensor interfacing circuit using 0.18-nm CMOS technology for MEMS application

Abstract

The aim of this paper is design of interface circuit while it is applied in capacitive sensor applications. In this paper, the circuits were designed in 0.18-μm Silterra CMOS technology and simulated in Mentor Graphic DA-IC. The proposed capacitive sensor includes two major building blocks: a wide-swing current mirror with enhanced output impedance which is usually used in wide-signal-swing op-amps, and an operational transconductance amplifier (OTA). OTA is an amplifier which its differential input voltage generate an output current. Thus, it is a voltage controlled current source (VCCS). The proposed OTA in this paper is a two-stage telescopic OTA that compared to the other types of OTA, it has higher gain, highest output swing and lower noise which are suitable for our target. In this paper, some parameters such as gain, power consumption and maximum output swing are given and compared with other researches to show relative performance of this circuit. The OTA with 78-dB gain and high-output swing has been driven by a high impedance current mirror which provides low error in its output voltage.