Practical charge-transfer amplifier design architectures for low-power flash A/D converters

William J. Marble, Koji Kotani, Craig S. Petrie

Research output: Contribution to journalArticlepeer-review

7 Citations (Scopus)


Two improved charge-transfer amplifiers (CTAs), used as zero-static-bias comparator preamplifiers in flash analog-digital converters, are proposed. The first improvement eliminates the capacitive coupling at the amplifier input, reducing area and input capacitance. The second eliminates the need for a common-mode output reference voltage by deriving the common-mode output from a switched average of the power supplies. In the latter, nearly a full-scale input range is achieved while preserving the low-power low offset characteristics of earlier CTAs. Voltage comparator devices were constructed in 0.6-μm double-poly, triple-metal CMOS to test the prototype CTA architectures. Input common-mode range and offset performance consistent with simulation data is demonstrated with a 10X reduction in input capacitance. Measured dynamic power dissipation on the order of 3-6 μW/MSPS is observed. The experimental CTA preamplifiers occupy roughly 0.015 mm2.

Original languageEnglish
Pages (from-to)2157-2164
Number of pages8
JournalIEEE Transactions on Circuits and Systems I: Regular Papers
Issue number11
Publication statusPublished - 2004 Nov
Externally publishedYes


  • Analog-digital (A/D) converter
  • Charge-transfer amplifier (CTA)
  • Low-power CMOS circuit design
  • Switched capacitor
  • Switched passive
  • Transconveyance amplifier
  • Voltage comparator

ASJC Scopus subject areas

  • Electrical and Electronic Engineering


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