An extended CMOS ISFET model incorporating the physical design geometry and the effects on performance and offset variation

Yan Liu*, Pantelis Georgiou, Themistoklis Prodromakis, Timothy G. Constandinou, Christofer Toumazou

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

Abstract

This paper presents an extended model for the CMOS-based ion-sensitive field-effect transistor, incorporating design parameters associated with the physical geometry of the device. This can, for the first time, provide a good match between calculated and measured characteristics by taking into account the effects of nonidealities such as threshold voltage variation and sensor noise. The model is evaluated through a number of devices with varying design parameters (chemical sensing area and MOSFET dimensions) fabricated in a commercially available 0.35-μm CMOS technology. Threshold voltage, subthreshold slope, chemical sensitivity, drift, and noise were measured and compared with the simulated results. The first- and second-order effects are analyzed in detail, and it is shown that the sensors' performance was in agreement with the proposed model.

Original languageEnglish
Article number6058632
Pages (from-to)4414-4422
Number of pages9
JournalIEEE Transactions on Electron Devices
Volume58
Issue number12
DOIs
Publication statusPublished - 21 Oct 2011

Keywords

  • Chemical sensor
  • CMOS
  • drift
  • geometry
  • ion-sensitive field-effect transistor (ISFET)
  • noise
  • passivation capacitance
  • subthreshold slope
  • threshold voltage

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