Design Equations for Lumped Element Balun With Inherent Complex Impedance Transformation
Journal article, 2017

This paper demonstrates a novel lumped design approach for complex impedance transformation, based on symmetry relaxation in the out-of-phase-compensated-power-splitter. In the modified topology, a total of four component values are used, of which two values analytically depend upon the other two, keeping the balance parameter maximally flat and independent of the source and load impedance, as well as of the balun internal components. From the condition of zero input reflection loss, the two other component values are also determined analytically, hence specifying all component values uniquely. A Monte Carlo sensitivity analysis predicts an amplitude imbalance, which in practice defines the limit in balance operational bandwidth, of better than +/-1 dB, over a 20% bandwidth at 925 MHz operating frequency. Based on the design equations, demonstrators for four different design cases are fabricated, verifying the simulated performance.


Balance parameter

complex impedance transformation

Monte Carlo analysis


Markus Frank

Chalmers, Microtechnology and Nanoscience (MC2), Electronics Material and Systems

Mattias Thorsell

Chalmers, Microtechnology and Nanoscience (MC2), Microwave Electronics

Peter Enoksson

Chalmers, Microtechnology and Nanoscience (MC2)

IEEE Transactions on Microwave Theory and Techniques

0018-9480 (ISSN) 15579670 (eISSN)

Vol. 65 12 5162-5170 8107540

Areas of Advance

Information and Communication Technology

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4/5/2022 6