Related Experiment Videos
A Low-Power Wide Dynamic-Range Current Readout Circuit for Ion-Sensitive FET Sensors
IEEE Transactions on Biomedical Circuits and Systems
|April 4, 2017
Summary
This study introduces a novel amplifier-less current-to-digital converter for ion-sensitive FET sensors. The digital-intensive design achieves efficient current conversion with first-order noise shaping and low power consumption.
Area of Science:
- * Electrical Engineering
- * Sensor Technology
- * Integrated Circuits
Background:
- * Ion-sensitive field-effect transistor (ISFET) sensors require efficient current-to-digital conversion for accurate signal processing.
- * Traditional converters often involve complex analog circuitry, leading to higher power consumption and larger footprints.
- * Developing digital-intensive solutions is crucial for miniaturization and integration in portable sensing devices.
Purpose of the Study:
- * To present an amplifier-less and digital-intensive current-to-digital converter (CDC) specifically designed for ISFET sensors.
- * To achieve first-order noise shaping of quantization error without continuous-time feedback circuits.
- * To minimize static power consumption through an innovative single-ended current-steering digital-to-analog converter (DAC) design.
Main Methods:
- * Utilization of input node capacitance as a residue accumulator for quantization.
- * Implementation of a clocked comparator for the analog-to-digital conversion process.
- * Employment of a single-ended current-steering DAC that mirrors the input current to reduce static power.
- * Adoption of a switching noise averaging algorithm for dynamic element matching to mitigate current source mismatch and noise.
Main Results:
- * The implemented 0.35 μm CMOS circuit successfully converts a current input range of 2.8 μA to a 15-bit digital output.
- * Achieved a conversion time of approximately 4 ms.
- * Demonstrated excellent linearity with Differential Nonlinearity (DNL) of +0.24/-0.25 Least Significant Bit (LSB) and Integral Nonlinearity (INL) of +1.98/-1.98 LSB.
- * Reported a low static power consumption of 16.8 μW.
Conclusions:
- * The proposed amplifier-less, digital-intensive CDC effectively converts ISFET sensor currents with high accuracy and low power.
- * The design achieves noise shaping and mitigates component mismatch through digital techniques, offering a robust solution.
- * This converter is suitable for low-power, integrated sensing applications where efficiency and miniaturization are paramount.