Design of a Switched Capacitor Negative Feedback Circuit for a Very Low Level DC Current Amplifier


To miniaturize a very low level dc current amplifier and to improve its output response speed, the switched capacitor negative feedback circuit (SCNF), instead of the conventionally used high-ohmage resistor, is presented in this paper. In our system, a switched capacitor filter (SCF) and an offset controller are also used to decrease vibrations and offset voltage at the output of the amplifier using SCNF. The theoretical output voltage of the very low level dc current amplifier using SCNF is obtained. The experimental results show that the unnecessary components of the amplifier’s output are much decreased, and that the response speed of the amplifier with both the SCNF and SCF is faster than that using high-ohmage resistor.

Share and Cite:

H. Higa and N. Nakamura, "Design of a Switched Capacitor Negative Feedback Circuit for a Very Low Level DC Current Amplifier," Circuits and Systems, Vol. 4 No. 4, 2013, pp. 356-363. doi: 10.4236/cs.2013.44048.

Conflicts of Interest

The authors declare no conflicts of interest.


[1] S. P. Presley, “Fast Response Picoammeter,” Review of Scientific Instruments, Vol. 37, No. 5, 1966, pp. 643-648. doi:10.1063/1.1720272
[2] K. Goto and K. Ishikawa, “Design and Construction of High Speed Pico-Ammeter,” The Journal of the Vacuum Society of Japan, Vol. 22, No. 6, 1979, pp. 235-246. doi:10.3131/jvsj.22.235
[3] I. Nakamura and T. Kano, “Noise and Fast Response of a Very Small dc Current Amplifier,” Oyo Buturi, Vol. 52, No. 4, 1983, pp. 330-338.
[4] F. Galliana and P. P. Capra, “Hamon 10 × 100 MΩ Resistor Based Traceable Source for Calibration of Pi coammeters in the Range 100 pA -100 nA,” Measurement, Vol. 43, No. 9, 2010, pp. 1277-1281. doi:10.1016/j.measurement.2010.07.006
[5] F. Galliana, P. P. Capra and E. Gasparotto, “Metrological Management of the High dc Resistance Scale at INRIM,” Measurement, Vol. 42, No. 2, 2009, pp. 314-321. doi:10.1016/j.measurement.2008.07.002
[6] I. Nakamura and M. Takemura, “Fast Respoinse of a Very Low-Level dc Current Amplifier Using Improve ment of Feedback Resistor Shielding Structure,” IEICE Transactions on Electronics, Vol. J72-C-II, No. 10, 1989, pp. 885-892.
[7] I. Nakamura and T. Kano, “High Speed Response of a Very Low Level dc Current Amplifier Using Positive Feedback Loop,” Oyo Buturi, Vol. 54, No. 9, 1985, pp. 945-951.
[8] A. B. Grebene, “Bipolar and MOS Analog Integrated Circuit Design,” John Wiley & Sons Inc., Hoboken, 1984.
[9] H. Higa, R. Onaga, N. Nakamura and I. Nakamura, “A Basic Study on a Very Low-Level dc Current Amplifier Using a Switched-Capacitor Circuit: Comparison between Simulation and Experimental Results,” Proceedings of ITC-CSCC2005, Jeju, 7 July 2005, pp. 1133-1134.
[10] N. H. E. Weste and K. Eshraghian “Principle of CMOS VLSI Design: A Systems Perspective,” T. Tomisawa and Y. Matsuyama, Translation, Maruzen, 1999.

Copyright © 2024 by authors and Scientific Research Publishing Inc.

Creative Commons License

This work and the related PDF file are licensed under a Creative Commons Attribution 4.0 International License.