Abstract
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 language | English |
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Pages (from-to) | 2157-2164 |
Number of pages | 8 |
Journal | IEEE Transactions on Circuits and Systems I: Regular Papers |
Volume | 51 |
Issue number | 11 |
DOIs | |
Publication status | Published - 2004 Nov |
Externally published | Yes |
Keywords
- 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