A Highly Sensitive Wide-Range Weak Current Detection Circuit for Implantable Glucose Monitoring

Abstract

A highly sensitive weak current detection circuit for implantable glucose monitoring is presented. The circuit consists of a current splitter, an integrator, a sampling/holding (S/H) circuit, and an 8-bit successive approximation register (SAR) analog-to-digital convertor (ADC). T-switches, source voltage shifting and correlated double sampling (CDS) technology are adopted to reduce the effects of leakage currents, charge injection, dc offset and low-frequency 1/f noise. The work range is divided into 5 sub-ranges to reduce the complexity and power consumption of current detection. The chip was fabricated with 0.13μm CMOS technology. Test results show that the circuit can detect weak signal from 10fA to 1nA with 1.5 V supply and 7.2μW power consumption. The tested leakage current of the design is 4fA.