A Wearable Real-time CMOS Dosimeter with Integrated Zero-bias Floating-Gate Sensor and an 86 inW 18-bit Energy-Resolution Scalable Time-based Radiation to Digital Converter

Radiation safety has become a major concern in recent years in healthcare, mining, security and nuclear applications. The problem is aggravated because of the absence of a real-time, accumulative radiation dosimeter of small form-factor that can provide digital output for continuous monitoring. In this paper, the first monolithically integrated wearable CMOS radiation dosimeter is presented, which consists a floating-gate resistive sensor with a sensitivity of 14ft/rad, and a time-based resistance to-digital-converter (RDC) functioning as an 18-bit ADC at 861n1 (at a measurement frequency of 100S/s) and 3.291)3/ conversionstep energy efficiency. Unlike traditional ADCs, the time-based RDC exhibits in-field resolution-energy scalability by controlling the total integrated time for measurement, and achieves 6-bit better resolution than state-of-the-art VCO-based low-frequency ( lkS/s) ADC architectures. The implemented integrated dosimeter achieves 8-bit better resolution and 7.5X lower power than the state-of-the-art CMOS Floating-Gate dosimeters. The dosimeter sensitivity is 40X better than the state-of-the-art with minimum resolvable dose reaching up to lOmrad.