High‐frequency wideband quadrature coupler using transformer and lumped elements

Abstract

A lumped quadrature coupler based on a ferromagnetic core is proposed for high-frequency (HF) application. The four terminals of the transformer are connected to the four ports, whereas two inductors and two capacitors are connected between two adjacent ports. The bandwidth is only limited by magnitude imbalance. A 13.56 MHz prototype is designed and tested. A 69% bandwidth is achieved with ±3 dB magnitude imbalance. Within the frequency band, the measured return loss is greater than 31.57 dB, port-to-port isolation is greater than 33.21 dB and the phase imbalance is <2°.

Compact size of the hybrid branch‐line coupler using π‐type transmission‐line

“…A lumped element approach was proposed in Ref. , where the combination of shunt capacitors (lumped element) and parallel coils was considered. In this case, the size of the structure is bulky due to coil device and the circuit is generated high cost and self‐resonant frequency (SRF) phenomenon.…”

Wideband filter-integrated coupled-line coupler with unequal power division and inherent DC-block function

“…Note that the insertion losses are relatively large and the bandwidth is extremely narrow, which limit its practical applications. In 2014, three different kinds of modified couplers were proposed in . The first one was suitable for high‐frequency (13.56 MHz) applications.…”

“…In 2014, three different kinds of modified couplers were proposed in . The first one was suitable for high‐frequency (13.56 MHz) applications. The second one focused on wideband operations.…”

“…The third one has dual‐band operations with chosen power division ratios and phase differences. It is obvious that all of these three couplers in do not integrate filtering function and the corresponding design processes are still complicated.…”