CMOS charge-transfer preamplifier for offset-fluctuation cancellation in low-power A/D converters

Koji Kotani, Tadashi Shibata, Tadahiro Ohmi

Research output: Contribution to journalArticlepeer-review

42 Citations (Scopus)


We have developed a low-power, high-accuracy comparator composed of a dynamic latch and a CMOS charge transfer preamplifier (CT preamplifier). The CT preamplifier amplifies the input signal with no static power dissipation, and the operation is almost insensitive to the device parameter fluctuations. The low-power and high-accuracy comparator has been realized by combining the CT preamplifier with a dynamic latch circuit. The fluctuation in the offset voltage of a dynamic latch is reduced by a factor of the preamplifier gain. A 4-bit flash A/D converter circuit has been designed and fabricated by 0.6-μm CMOS process. Low differential nonlinearity of less than ±4 mV has been verified by the measurements on test circuits, showing 8-bit resolution capability. Very low power operation at 4.3μW per MS/s per comparator has also been achieved.

Original languageEnglish
Pages (from-to)762-768
Number of pages7
JournalIEEE Journal of Solid-State Circuits
Issue number5
Publication statusPublished - 1998 May
Externally publishedYes


  • A/D converter
  • Charge transfer preamplifier
  • Comparator
  • Dynamic latch
  • Low power

ASJC Scopus subject areas

  • Electrical and Electronic Engineering


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