A chopper-stabilized source follower coupling based low-pass filter with noise reduction

  • Yang Xu
  • Un-Ku Moon
Mixed Signal Letter


A highly compact source follower coupling based low-pass filter (LPF) topology is proposed that synthesizes a 3rd-order low-pass transfer function in a single stage with no use of operational amplifiers. Chopper stabilization technique is utilized to reduce 1/f noise for minimizing the in-band integrated noise. Implemented and simulated in a 0.18 μm CMOS process, the 3rd-order LPF achieves a − 3 dB bandwidth of 20 MHz with a 280 μA total current from a 1.4 V supply voltage, defining a power-per-pole/bandwidth efficiency of 6.5 μW/MHz. The output noise density at low frequencies is largely reduced with chopper stabilization technique. The integrated output noise from 10 kHz to 2 MHz is minimized from 22.47 to 7.04 μVrms, with a 10.1 dB improvement. The averaged output noise density over the filter bandwidth is 9.4 nV/√Hz, which is mostly contributed by thermal noise of transistors.


Low-pass filter Chopper stabilization 1/f noise Noise reduction Source follower coupling 



Funding was provided by Semiconductor Research Corporation (Grant No. 2550.021).


  1. 1.
    Xu, Y., Leuenberger, S., Venkatachala, P., & Moon, U. (2016). A 0.6 mW 31 MHz 4th-order low-pass filter with +29 dBm IIP3 using self-coupled source follower based biquads in 0.18 μm CMOS. In IEEE symposium on VLSI circuits, pp. 132 − 133.
  2. 2.
    Enz, C., & Temes, G. (1996). Circuit techniques for reducing the effects of op-amp imperfections: Autozeroing, correlated double sampling, and chopper stabilization. Proceedings of the IEEE, 84(11), 1584–1614. Scholar

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© Springer Science+Business Media, LLC, part of Springer Nature 2018

Authors and Affiliations

  1. 1.School of Electrical Engineering and Computer ScienceOregon State UniversityCorvallisUSA

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