CMOS Integrated Magnetless Circulators Based on Spatiotemporal Modulation Angular-Momentum Biasing

TL;DR

This paper presents the first integrated CMOS circuit implementation of magnetless circulators using spatiotemporal modulation with angular-momentum biasing, achieving significant size reduction and practical chip-scale realization.

Contribution

It introduces a novel CMOS IC design for spatiotemporally modulated magnetless circulators with a simplified topology and validated performance.

Findings

Good agreement between simulated and measured results.

Significant size reduction compared to previous implementations.

Reliable performance in CMOS technology.

Abstract

In this paper, we introduce the first integrated circuit (IC) implementation of spatiotemporally modulated angular-momentum (STM-AM) biased magnetless circulators. The design is based on a modified current-mode topology which is less sensitive to parasitics and relies on switched capacitors rather than varactors to achieve the desired modulation, thus reducing the circuit complexity and easing its chip-scale realization. We analyze the presented circuit and study its performance in the presence of inevitable non-idealities using an in-house so-called composite Floquet scattering matrix (CFSM) numerical method. We also validate the analysis with simulated and measured results using a standard 180 nm CMOS technology, showing good performance. Compared to previous discrete implementations of STM-AM circulators, the presented CMOS chip reduces the form factor by at least an order of magnitude and occupies a total area of only 36 mm2.