A Compact and Wideband mmWave Passive CMOS Circulator Based on Switched All-Pass Networks

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openAccess

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Journal Title

Journal ISSN

Volume Title

A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä

Date

2024

Major/Subject

Mcode

Degree programme

Language

en

Pages

4
41-44

Series

IEEE Microwave and Wireless Technology Letters, Volume 34, issue 1

Abstract

This letter presents a compact and wideband passive CMOS circulator for mmWave phased array transceivers. The letter focuses on achieving a compact die area while still offering competitive performance in terms of loss, isolation, and linearity. Our implemented circulator includes two reciprocal phase shift branches as well as a single-path nonreciprocal phase shift branch. We propose to use first-order lattice all-pass filters with coupled inductors to create the required phase shifts, which offer more compact, wideband, and predictable results compared to conventional lattice all-pass filters with two separate inductors. We also propose to use four identical first-order lattice cells in reciprocal and nonreciprocal branches. This can further reduce the size of the nonreciprocal branch due to fewer inductors compared to a typical second-order all-pass filter like bridged-T. The circuit is implemented in a 28 nm CMOS process, and the active die area is only $0.17~\text {mm}^{{2}}$ . Our measurements demonstrate that the implemented circulator operates over a 1 dB insertion loss bandwidth of 14–28 GHz that achieves 66% fractional bandwidth with an insertion loss of 3.8 dB, isolation of over 20 dB, and input third-order intercept point of +19 dBm.

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Keywords

Circulators, Inductors, Millimeter wave communication, Microwave filters, Loss measurement, Lattices, Wideband

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Citation

Naghavi , S , Gao , J , Stadius , K & Ryynänen , J 2024 , ' A Compact and Wideband mmWave Passive CMOS Circulator Based on Switched All-Pass Networks ' , IEEE Microwave and Wireless Technology Letters , vol. 34 , no. 1 , 10314534 , pp. 41-44 . https://doi.org/10.1109/LMWT.2023.3329963