Design of a humidity sensor with PVT variations using AMI C5 CMOS technology

Humidity sensor can be defined as a device, which consists of plastic material whose characteristics change as per the amount of humidity present in the air. Its various application areas include controlling of the climate, storage of food articles, domestic applications etc. The reference paper implemented the humidity sensor uses post-CMOS processing of CMOS fabricated chips to obtain suspended and thermally isolated diodes. However, the paper does not include the read out circuit and the design of op-amp. Industry however always considers the design under PVT (process, voltage & temperature) variations to make it commercial. This paper aims in designing op-amp, which is used in the read out circuit of the CMOS humidity sensor based on PVT variation (process, voltage and temperature variation). The design issues for switch capacitor used in the humidity sensor are also described. The thermal design equations for the sensor diode model have also been considered and presented.