Calibration of ASIC for pressure sensors

• Main Author: Qin, Tianhe
• Other Authors: Goh Wang Ling
• Format: Final Year Project
• Language: English
• Published: 2014
• Subjects: DRNTU::Engineering::Electrical and electronic engineering::Integrated circuits
• Online Access: http://hdl.handle.net/10356/60422
• Institution: Nanyang Technological University

Modern circuitry systems have brought thermal issues into the spotlight due to increases in circuit density and complexity of components. Previous research has indicated that the thermal problem can cause significant performance decay as well as reducing of circuitry reliability.[1] As such, temperature sensors are widely implemented in modern systems. In the last couple of years, CMOS temperature sensors have become increasingly popular due to the rapid growth of Integrated Circuit(IC) industry.[2] The temperature sensors are generally constructed using BJT (Bi-polar Junction Transistors) or MOSFET (Metal-Oxide Semiconductor Field-Effect Transistor) and are able to achieve a relatively linear voltage-temperature output relationship. However, there are still some limitations when using such temperature sensors, with non-linearity being a significant factor. This project aims to design a MOSFET temperature sensor with high non-linearity (≤1.0%) over a temperature range of -25℃ to 125℃, with a voltage input of 1.8V using the 0.18μm process. The output voltage is also expected to have temperature sensitivity of at least 5mV/℃ amongst other specifications. Two final temperature sensor circuits are being presented in this paper. The first circuit comprises of a basic MOSFET temperature sensor circuit with the implementation of a trimmer to maintain linearity of the sensor’s output in the case of varying circuit environment and conditions. The second circuit uses two identical basic MOSFET temperature sensor circuits with similar outputs and passed through a differential single-stage 5-transistor operational amplifier so as to remove higher-order temperature coefficients, thus reducing the non-linearity of the final output.