Analysis and optimization of noise in continuous-time OTA-C filters

Slawomir Koziel*, Rolf Schaumann, Haiqiao Xiao

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

18 Citations (Scopus)


A general procedure is presented for noise analysis and optimization in continuous-time operational transconductance amplifier (OTA)-C filters of arbitrary order and topology. Based on a matrix description of a general OTA-C filter structure, universal expressions are derived that permit computing the filter noise and optimizing the noise performance in any OTA-C filter. The results are not only useful for classical (discrete or integrated) OTA-C designs at medium to high frequencies but also in modern radio-frequency integrated circuits (RFICs) by carefully replacing transistors or electronic subcircuits by OTA (macro) models. The formulas are easy to implement and are readily included in computer-aided analysis and optimization algorithms. The accuracy of the proposed algebraic method is confirmed by a comparison with SPICE-simulation results. Two application examples are given: Finding the minimum-noise a multiple-loop-feedback filter configuration to implement fifth-order Butterworth and Bessel transfer functions, and determining the optimal biquad sequencing and gain distribution in a cascade realization of an eighth-order Butterworth filter.

Original languageEnglish
Pages (from-to)1086-1094
Number of pages9
JournalIEEE Transactions on Circuits and Systems I: Regular Papers
Issue number6
Publication statusPublished - Jun 2005

Bibliographical note

Funding Information:
Manuscript received May 6, 2004; revised October 23, 2004. This work was supported in part by the State Scientific Research Committee, Poland, under Grant 4T11B01625. This paper was recommended by Associate Editor A. Wang.

Other keywords

  • Filter optimization
  • Noise analysis
  • Operational transconductance amplifier (OTA)-C filters


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