Compact and Slow-Wave Tunable 28 nm CMOS-SOI Twisted Hybrid Couplers for 5G Applications

This article presents four twisted hybrid couplersexhibiting low insertion losses for 5G applications. Thanks to anaccurate pre-sizing methodology and an electromagnetic model,three different twisted hybrid coupler architectures are presentedand compared to offer different form factor trade-offs whilemaintaining state-of-the-art performances. A 26-44-GHz multi-band 90(degrees )twisted hybrid coupler exhibiting low insertion lossesis then presented to improve its inherent bandwidth. Using atunable 3-bit slow-wave architecture, the hybrid coupler offerseight operating modes allowing it to select the desired centerfrequency and covers a bandwidth of more than 51% whileminimizing its losses. The hybrid coupler achieves insertion losseslower than 2.2 dB with a minimum of 1.45 dB at 26 GHz anda phase shift between the two output paths of 95(degrees)+/- 5(degrees). Thecoupler is highly robust to process variations, and offers a highpower handling up to 35 dBm input. All of these circuits areimplemented in a CMOS 28 nm FD-SOI process.