Stability Analysis of Non-Foster Circuit Using Normalized Determinant Function

Qi Tang, Hao Xin

Research output: Contribution to journalArticlepeer-review

18 Scopus citations


Non-Foster elements are highly desired to overcome the bandwidth limit of electrically small antennas, cloaking, and metamaterials. However, they are prone to be unstable and thus it is quite challenging to implement non-Foster circuits in practice. Hence a rigorous and effective method of analyzing the stability should always be the priority when designing a non-Foster network. This paper applies normalized determinant function to analyze the stability of non-Foster circuits. A floating-version negative capacitor based on Linvill's negative impedance converter is taken as the example. Factors affecting the stability in the practical design are thoroughly investigated, including device parasitics, dc biasing, distributed transmission line in the layout and load impedance. Circuit parameters are substituted with practical values to reduce the complexity of calculation. Finally, experiments are conducted to verify the analysis.

Original languageEnglish (US)
Article number7898508
Pages (from-to)3269-3277
Number of pages9
JournalIEEE Transactions on Microwave Theory and Techniques
Issue number9
StatePublished - Sep 2017


  • Negative impedance converter
  • non-Foster circuit
  • normalized determinant function (NDF)
  • stability analysis

ASJC Scopus subject areas

  • Radiation
  • Condensed Matter Physics
  • Electrical and Electronic Engineering


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