A Low-Power Wide Dynamic-Range Current Readout Circuit for Ion-Sensitive FET Sensors

作者：Son Hyunwoo^*; Cho Hwasuk; Koo Jahyun; Ji Youngwoo; Kim Byungsub; Park Hong June; Sim Jae Yoon

来源：IEEE Transactions on Biomedical Circuits and Systems, 2017, 11(3): 523-533.

DOI：10.1109/TBCAS.2016.2643784

• Biosensor applications
• current readout circuit
• current-to-digital converter
• delta-sigma modulation
• ion-sensitive FET
• ultra-low-power

This paper presents an amplifier-less and digital-intensive current-to-digital converter for ion-sensitive FET sensors. Capacitance on the input node is utilized as a residue accumulator, and a clocked comparator is followed for quantization. Without any continuous-time feedback circuit, the converter performs a first-order noise shaping of the quantization error. In order to minimize static power consumption, the proposed circuit employs a single-ended current-steering digital-to-analog converter which flows only the same current as the input. By adopting a switching noise averaging algorithm, our dynamic element matching not only mitigates mismatch of current sources in the current-steering DAC, but also makes the effect of dynamic switching noise become an input-independent constant. The implemented circuit in 0.35 mu m CMOS converts the current input with a range of 2.8 mu A to 15b digital output in about 4 ms, showing a DNL of + 0.24/ - 0.25 LSB and an INL of + 1.98/ - 1.98 LSB while consuming 16.8 mu W.

• 出版日期2017-6