A CMOS temperature difference to frequency converter with calibration circuits for environmental temperature difference monitoring applications

In this paper, a CMOS temperature difference to frequency converter with calibration circuits for environmental temperature difference monitoring applications is newly proposed. A calibration technique is proposed in this work. Another innovation is that the outputs of the proposed chip are directly digitized, they could be easily sent over a wide range of transmission media, such as PSN, radio, optical, IR, ultrasonic, and etc. Before performing the proposed calibration circuits, the maximum linear error is 10.84%. After calibration, the maximum linear error is reduced to 0.54%. The temperature difference ranges from 12.43 to 36.7 °C, and the corresponding output frequency range is 150.49 to 432.81 kHz. The chip area is 1.25 × 1.24 mm². The proposed chip is suitable for devices of measuring temperature difference.