Search

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 nonidealities 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. [ABSTRACT FROM AUTHOR]

Nonreciprocal components, such as isolators and circulators, are critical to wireless communication and radar applications. Traditionally, nonreciprocal components have been implemented using ferrite materials, which exhibit nonreciprocity under the influence of an external magnetic field. However, ferrite materials cannot be integrated into IC fabrication processes and, consequently, are bulky and expensive. In the recent past, there has been strong interest in achieving nonreciprocity in a nonmagnetic IC-compatible fashion using spatio-temporal modulation. In this paper, we present a general approach to nonreciprocity based on switched transmission lines. Switched transmission lines enable broadband, lossless, and compact nonreciprocity and a wide range of nonreciprocal functionalities, including nonreciprocal phase shifters, ultra-broadband gyrators and isolators, frequency-conversion isolators, and high-linearity/high-frequency/ultra-broadband circulators. We present a detailed theoretical analysis of the various nonidealities that impact insertion loss and provide design guidelines. The theory is validated by experimental results from discrete-component-based gyrators and isolators and a 25-GHz circulator fabricated in a 45-nm SOI CMOS technology. [ABSTRACT FROM AUTHOR]