Senzori de temperatură monolitici avansați / Advanced monolithic temperature sensors

Precision thermometry may be achieved through a large range of methods. The outstanding problem is how to do so with as little costs, as conveniently and as precisely possible. There is scope in researching performance improvements of monolithic temperature sensors without sacrificing their other attributes (like low power, cost and size), thus allowing them to displace more expensive solutions in precision markets, at least for applications with temperature ranges compatible to operating temperature ranges of silicon-based integrated circuits. In this research, the accent is put on development of circuits with improved linearity which may be used in monolithic temperature sensors, thus reducing the required number of calibration points, and therefore lowering the total cost of use in precision applications. New circuit architectures for bandgap temperature sensors are proposed and implemented to design and release commercially monolithic temperature sensors in standard CMOS / BiCMOS manufacturing processes. Further research which seeks to address the residual nonlinearity of the proposed designs is then presented as an architecture developed to the level of advanced simulation. Also, the development of an architecture of a suitable sigma-delta analogue-to- digital converter (ADC) to process the output of temperature sensing circuits is further investigated. A new mathematical method of describing the operation of feed-forward discrete time second-order sigma-delta topologies is discussed, and a multi-bit ADC architecture suitable for DC signals while maintaining good linearity is proposed. Finally, the measured performance of this work is discussed in relation with other state of the art temperature measurement solutions. Figures of merit established in the field are used to make meaningful comparations. Conclusions are drawn, and future avenues for research uncovered during this work are discussed.