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9.4 W 285 Samples/s Capacitance to Digital Converter for Large Area Active EWOD Arrays in Thin-Film Transistor Technology

delete2026-01-01
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PRE
AI
L
Lopez, Mauricio Velazquez *
P
Papadopoulos, Nikolas
B
Berghmans, Francois
M
Myny, Kris
DOI:10.1109/OJCAS.2026.3670665delete
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Abstract

Abstract

En 中文
This work introduces a low-power, linear-in-log capacitance sensing circuit tailored for large-area electrowetting-on-dielectric (EWOD) arrays utilizing thin-film transistor (TFT) technology. By leveraging the intrinsic time constants of the circuit, the proposed approach achieves enhanced sensitivity at low capacitance levels, effectively addressing scenarios where the EWOD electrode capacitance is on par with parasitic capacitances present in the system. Fabricated using a 4.5 & micro;m Low Temperature Polysilicon (LTPS) TFT process, the circuit demonstrates up to 6-bit resolution, corresponding to 63 distinct measured capacitance levels, and measures capacitance variations as small as 61.3 fF. Two circuit variants are presented: the first, employing a one-transistor-one-resistor (1T1R) input stage, which operates at a peak/mean power consumption of 16 & micro;W / 3.0 & micro;W and occupies 324 & times; 324 & micro;m(2); the second, incorporating a current mirror (CM) input stage, consumes 35 & micro;W / 9.4 & micro;W with an area of 317 & times; 506 & micro;m(2). Both implementations mark a significant improvement in resolution, sensitivity and power efficiency compared to the current state-of-theart in TFT technology.
Keywords:
Capacitors
Circuits
Integrated circuits
Circuit synthesis
Circuits and systems
Current mirrors
Voltage-controlled oscillators
Voltage multipliers
Diodes
System-on-chip
Thin-film transistors (TFTs)
electrowetting-on-dielectric (EWOD)
capacitance sensing
large area sensing systems
low temperature polysilicon (LTPS)
linear-in-log
high resolution
low power

Journal

I
IEEE Open Journal of Circuits and Systems
IF:
2.4
Papers:
4.5K
Citations:
387

Organization

I
interuniversity microelectronics centre
Scholars:
6.2K
Papers: 3.9K
Citations: 0
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