This paper presents the design of a low-complexity, linear and sub-pF CMOS capacitance-frequency converter for reading out capacitive bacterial bio/sensors in an attempt to create a widespread bio/sensor readout module. The significant design objectives included a high resolution as well as an extensive dynamic range. The circuit was based on a method which outputs a digital frequency signal directly from a differential capacitance by the accumulation of charges produced by repetitive charge integration and charge preservation. A prototype was designed for manufacture using the 0.35 µm, 3.3V ams CMOS technology. At a 1 MHz clock speed, the results obtained for the designed converter were: (i) a power consumption of 1.37mW; (ii) a resolution of at least 5fF for sensitive capacitive transduction; (iii) an input dynamic range of at least 43.5 dB from a measurable capacitance value range of 5-750fF and (iv) a Pearson's coefficient of linearity of 0.99. Furthermore, a large-scale CFC was constructed with discrete IC's in order to verify the function of the CMOS design.
Reference:
Ghoor, IS, Bezuidenhut PH, Joubert TH. 2017. High-resolution capacitance-frequency converter for biosensor applications. IEEE Africon 2017 Proceedings, 18-20 September 2017, V&A Waterfront, Cape Town, South Africa, 4pp.
Ghoor, I. S., Bezuidenhout, P. H., & Joubert, T. H. (2017). High-resolution capacitance-frequency converter for biosensor applications. IEEE. http://hdl.handle.net/10204/10382
Ghoor, Ikraam S, Petrone H Bezuidenhout, and Trudi H Joubert. "High-resolution capacitance-frequency converter for biosensor applications." (2017): http://hdl.handle.net/10204/10382
Ghoor IS, Bezuidenhout PH, Joubert TH, High-resolution capacitance-frequency converter for biosensor applications; IEEE; 2017. http://hdl.handle.net/10204/10382 .
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