A 3-bit pseudo flash ADC based low-power CMOS interface circuit design for optical sensor

The paper presents a CMOS interface circuit design for optical pH measurement that can produce an 8-bit digital output representing the color information (i.e., wavelength, l). In this work we are focusing at reducing the component count by design and hence reducing the cost and silicon area. While it could be further optimized for lower power consumption, the proposed design has been implemented using standard cells provided by the foundry (i.e., AMS 0.35 μm CMOS) for proof of concept. The biasing current and power consumption of the fabricated chip are measured at 11 μA and 37 μW respectively using 3.3 V supply voltage. Experimental results have further validated the proposed design concept. The number of detectable colors is eight and can be extended to a higher number without any major change in the architecture.