Switched-Capacitor Level-Shifting Technique With Sampling Noise Reduction for Rail-to-Rail Input Range Instrumentation Amplifiers

This paper proposes a switched-capacitor Adaptive Level-Shifting (ALS) technique for Instrumentation Amplifiers (IA). When used at the front end of an IA the ALS circuit enables true rail-to-rail input common-mode (CM) range and reduces CMRR requirements for the following IA. In the proposed implementation, two ALS circuits are combined with the two input stages of an Indirect Current-Feedback (ICF) IA. To overcome the limited input differential voltage range of such IAs, the ALS circuits are cross-connected. As a result the IA has a wide input differential range and a true rail-to-rail input CM range. The IA is fabricated in 0.18 μm CMOS process, achieves 70 nV/√Hz noise spectral density, 115 μA supply current, 20 μV input offset voltage, 130 dB CMRR and 20 ppm gain error.

[1]  Wilko J. Kindt,et al.  A 140 dB-CMRR Current-Feedback Instrumentation Amplifier Employing Ping-Pong Auto-Zeroing and Chopping , 2010, IEEE Journal of Solid-State Circuits.

[2]  Johan H. Huijsing,et al.  Indirect Current Feedback Instrumentation Amplifier with a Common Mode Input Range That Includes the Negative Rail , 1992 .

[3]  Johan H. Huijsing,et al.  Compact low-voltage power-efficient operational amplifier cells for VLSI , 1998, IEEE J. Solid State Circuits.

[4]  J.H. Huijsing,et al.  A Chopper Current-Feedback Instrumentation Amplifier With a 1 mHz $1/f$ Noise Corner and an AC-Coupled Ripple Reduction Loop , 2009, IEEE Journal of Solid-State Circuits.

[5]  G. Geelen,et al.  A fast-settling CMOS op amp for SC circuits with 90-dB DC gain , 1990 .

[6]  Shouli Yan,et al.  A Robust Rail-to-Rail Input Stage with Constant-gm and Constant Slew Rate Using a Novel Level Shifter , 2007, 2007 IEEE International Symposium on Circuits and Systems.

[7]  Kofi A. A. Makinwa,et al.  A 1.8 $\mu$ W 60 nV$/\surd$ Hz Capacitively-Coupled Chopper Instrumentation Amplifier in 65 nm CMOS for Wireless Sensor Nodes , 2011, IEEE Journal of Solid-State Circuits.

[8]  M.F. Snoeij,et al.  A 36 V Programmable Instrumentation Amplifier With Sub-20 $\mu$V Offset and a CMRR in Excess of 120 dB at All Gain Settings , 2009, IEEE Journal of Solid-State Circuits.

[9]  John W. Jaquay.  Designers Guide to: Instrumentation amplifiers , 1977 .

[10]  J. Szynowski.  CMRR analysis of instrumentation amplifiers , 1983 .

[11]  Kofi A. A. Makinwa,et al.  A 21 nV/$\surd$ Hz Chopper-Stabilized Multi-Path Current-Feedback Instrumentation Amplifier With 2 $\mu$ V Offset , 2012, IEEE Journal of Solid-State Circuits.

[12]  Kofi A. A. Makinwa,et al.  A capacitively coupled chopper instrumentation amplifier with a ±30V common-mode range, 160dB CMRR and 5μV offset , 2012, 2012 IEEE International Solid-State Circuits Conference.

[13]  Un-Ku Moon,et al.  An Over-60 dB True Rail-to-Rail Performance Using Correlated Level Shifting and an Opamp With Only 30 dB Loop Gain , 2008, IEEE Journal of Solid-State Circuits.

[14]  D. Draxelmayr,et al.  A chopped Hall sensor with small jitter and programmable "True Power-on" function , 2005, IEEE Journal of Solid-State Circuits.

[15]  P.R. Gray,et al.  A MOS switched-capacitor instrumentation amplifier , 1982, IEEE Journal of Solid-State Circuits.