Automatic Offset Correction for Measurements in the Nanovolt Range

In this paper, the design of a new offset correction system employing a time-varying resistance as a probe for the detection of the sign and magnitude of the equivalent input offset of an operational amplifier in a series–shunt feedback configuration is presented. In order to considerably reduce the charge injection effects resulting from the switching of the MOS transistor that is used for the implementation of the time-varying resistance, we resort to a proper discrete time-sampling strategy for offset error detection. With respect to a previous topology, the new approach allows us to extend the useful amplifier bandwidth from a few hertz up to about 100 Hz with a gain boost from 201 to 1001. With the new approach, a residual offset on the order of a few tens of nanovolts is obtained, which allows us to classify the system as a nanovolt amplifier.

[1]  Zeynep Celik-Butler,et al.  Characterization of MEMS piezoresistive pressure sensors using AFM. , 2010, Ultramicroscopy.

[2]  Gabor C. Temes,et al.  Circuit techniques for reducing the effects of op-amp imperfections: autozeroing, correlated double sampling, and chopper stabilization , 1996, Proc. IEEE.

[3]  A. Lakhani,et al.  Simple and precise thermoelectric power measurement setup for different environments. , 2008, The Review of scientific instruments.

[4]  L. Storm,et al.  On the excess noise of dc current-carrying thin metal wires in dilute gases of different kind and pressure , 1985 .

[5]  G. Scandurra,et al.  Nanovoltmeter amplifier for low level voltage measurements , 2012, 2012 IEEE International Instrumentation and Measurement Technology Conference Proceedings.

[6]  A. Bakker,et al.  A CMOS nested-chopper instrumentation amplifier with 100-nV offset , 2000, IEEE Journal of Solid-State Circuits.

[7]  Carmine Ciofi,et al.  A Very Low Offset Preamplifier for Voltage Measurements in the $\mu\hbox{V}$ Range , 2010, IEEE Transactions on Instrumentation and Measurement.

[8]  J.B. McCormick,et al.  Distortion and noise-induced DC offset in operational amplifiers , 1975, IEEE Journal of Solid-State Circuits.

[9]  Miguel Angel Mayosky,et al.  AC coupled three op-amp biopotential amplifier with active DC suppression , 2000, IEEE Transactions on Biomedical Engineering.

[10]  Torsten Funck,et al.  Improved High-Input-Impedance mV-Amplifiers With Gain Factors From 10 to 900 , 2009, IEEE Transactions on Instrumentation and Measurement.