Open AccessSemi-lumped Balun Transformer using Coupled LC Resonators
Author(s) -
Jong-Cheol Park,
Minkyu Yoon,
Jae Yeong Park
Publication year - 2015
Publication title -
journal of electrical engineering and technology/journal of electrical engineering and technology
Language(s) - English
Resource type - Journals
eISSN - 2093-7423
pISSN - 1975-0102
DOI - 10.5370/jeet.2015.10.3.1154
Subject(s) - balun , transformer , resonator , electrical engineering , acoustics , materials science , electronic engineering , physics , engineering , voltage , antenna (radio)
This paper presents a semi-lumped balun transformer using conventional PCB process and its design theory and geometry for the maximally flat response and wide bandwidth using magnetically coupled LC resonators. The proposed balun is comprised of two pairs of coupled resonators which share one among three LC resonators. It provides an identical magnitude and phase difference of 180° between two balanced ports with DC isolation and an impedance transformation characteristic. Theoretical design and analysis were performed to optimize the inductance and capacitance values of proposed balun device for obtaining the wide bandwidth and maximally flat response in its pass-band. Three balun transformers with a center frequency of 500 MHz were demonstrated for proving the concept of design proposed. They were fabricated by using lumped chip capacitors and planar inductors embedded into a conventional 4-layered PCB substrate. They exhibited a maximum magnitude difference of 0.8 dB and phase difference within 2.4 degrees.