Precision Temperature Sensors in CMOS Technology (Analog Circuits and Signal Processing)

This book describes the analysis and design of precision temperature sensors in CMOS IC technology. It focusses on so-called smart temperature sensors, which provide a digital output signal that can be readily interpreted by a computer. The sensors described in this book are based on bipolar transistors, which are available as parasitic devices in standard CMOS technology. The relevant physical properties of these devices are described. It is shown in detail how their temperature characteristics can be used to obtain an accurate digital temperature reading. A sigma-delta converter plays a key role in the conversion to a digital output. Both the system-level design of such a converter, and the circuit-level implementation using both continuous-time and switched-capacitor techniques are described. Special attention is paid to the application of precision interfacing techniques, such as dynamic offset cancellation and dynamic element matching. A separate chapter is devoted to low-cost calibration techniques. Precision Temperature Sensors in CMOS Technology ends with a detailed description of three realized prototypes. The final prototype achieves an inaccuracy of only ±0.1ºC (3Sigma) over the temperature range of –55ºC to 125ºC, which is the highest performance reported to date.