A 30.3 fA/√Hz Biosensing Current Front-End With 139 dB Cross-Scale Dynamic Range
- Resource Type
- Periodical
- Authors
- Ying, D.; Tseng, C.; Chen, P.; Lo, Y.; Hall, D.
- Source
- IEEE Transactions on Biomedical Circuits and Systems IEEE Trans. Biomed. Circuits Syst. Biomedical Circuits and Systems, IEEE Transactions on. 15(6):1368-1379 Dec, 2021
- Subject
- Bioengineering
Components, Circuits, Devices and Systems
Sensors
Proteins
Delta-sigma modulation
Biosensors
Quantization (signal)
Biosensor
current front-end
CT ΔΣ
IIR quantizer
sub-pA
tri-level DAC
- Language
- ISSN
- 1932-4545
1940-9990
This paper presents an 8-channel array of low-noise (30.3 fA/√Hz) current sensing front-ends with on-chip microelectrode electrochemical sensors. The analog front-end (AFE) consists of a 1 st -order continuous-time delta-sigma (CT ΔΣ) modulator that achieves 123 fA sensitivity over a 10 Hz bandwidth and 139 dB cross-scale dynamic range with a 2-bit programmable current reference. A digital predictor and tri-level pulse width modulated (PWM) current-steering DAC realize the equivalent performance of a multi-bit ΔΣ in an area- and power-efficient manner. The AFE consumes 50.3 µW and 0.11 mm 2 per readout channel. The proposed platform was used to observe protein-ligand interactions in real-time using transient induced molecular electronic spectroscopy (TIMES), a label- and immobilization-free biosensing technique.