CMOS Sigma-Delta Thermal Modulator

This work presents the design of a 1(st)-order sigma-delta thermal modulator using a thermoresistive sensor in its feedback loop, as the summing and integrating elements. The proposed system architecture allows the measurement of physical quantities that interact with the sensor, as temperature, thermal radiation and fluid velocity. Procedures for obtaining the design specifications needed for its modeling in VHDL-AMS are presented. A layout for the sigma-delta thermal modulator was developed for the integrated circuit technology CMOS 0.35 mu m. Simulation results from this layout for temperature measurement are presented, showing that a resolution of 8.7 bits was attained, for a input signal frequency range of 12.5 kHz and a sampling frequency of 25.6 MHz.