A Quiet Digitally Assisted Auto-Zero-Stabilized Voltage Buffer with 0.6pA Input Current and 0.6μV Offset

Conference paper (2018)

Authors

C.T. Rooijers Electronic Instrumentation - EEMCS
J.H. Huijsing Electronic Instrumentation - EEMCS
K.A.A. Makinwa Microelectronics
Research Group
Electronic Instrumentation (EEMCS) (TU Delft)
Copyright: © 2018 C.T. Rooijers, J.H. Huijsing, K.A.A. Makinwa
DOI
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https://doi.org/10.1109/ISSCC.2018.8310178
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Published Date

2018

Language

English

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Faculty

Electrical Engineering, Mathematics and Computer Science

Department

Microelectronics

Research Group

Electronic Instrumentation

Abstract

The readout of high impedance sensors and sampled voltage references [1]
requires amplifiers with both low offset and low input current. Chopper amplifiers
can achieve low offset, but the switching of their input chopper gives rise to
significant input current (40 to 110pA) [2-4]. Auto-zero (AZ) amplifiers require
less input switching, but exhibit more voltage noise. However, ping-pong
amplifiers continuously swap two auto-zeroed input stages, leading to more
switching [5,7]. In this work, an AZ stabilized topology is proposed, in which a
single amplifier is always present in the signal path. Only one input switch is
required, resulting in an input current of 0.6pA (max), a 66× improvement on the
state-of-the art [4]. Furthermore, a digitally assisted offset-reduction scheme
reduces its low-frequency (LF) noise to the theoretical √5× limit. It also achieves
a state-of-the-art maximum offset of 0.6μV.