A low-power wide dynamic-range current readout circuit for biosensors.

This paper presents an amplifier-less and digital-intensive current-to-digital converter for biosensors. The proposed circuit achieves a first-order noise shaping of the quantization error without any continuous-time feedback circuit. Also, it minimizes static power consumption by employing a single-ended current-steering digital-to-analog converter (DAC) which flows only the same current as the input. The effect of dynamic switching noise become input-independent constant by adopting switching averaging algorithm. The implemented circuit in 0.35μm CMOS converts an input range of 2.8μA to 15b digital output in about 4ms, while consuming 16.8μW.