A CMOS integrated capacitance-to-frequency converter with digital compensation circuit designed for sensor interface applications

Abstract

In this work, a capacitive signal conditioner of a CMOS integrated capacitance-to-frequency converter wit h digital compensation circuit designed for sensor interface applications is newly proposed. The proposed converter has the low cost feature. That is due to that the output signal of the proposed converter is a digitized signal produced without realizing the analog to digital converter. Hence, the hardware cost could be reduced. Besides, the output of the proposed converter is a pulse stream, it could be easily sent over a wide range of transmission media, such as PSN, radio, optical, K ultrasonic, and etc. Based upon 0.35 um 2P4M CMOS technology, measurement results have successfully verified the correct functions and performance of the integrated capacitance-to-frequency converter with digital compensation circuit designed for sensor interface applications. The area of this fabricated chip is 940 x 1080 um 2 and the power consumption is 6.4 mW. The proposed converter is not only suitable for capacitive measurement systems, but also applications of demanding wide dynamic output frequency range.