arXiv subjects

Andreia Cathelin

Publications and source records attributed to Andreia Cathelin.

4 recordsLinked to original sources

arXiv2026

A Study on THz Plasmonics in a CMOS Continuum Transistor Array

This work addresses the limitations of CMOS at terahertz (THz) frequencies, where charge transit time and parasitic capacitances restrict the maximum operating frequency, fmax. As transistor dimensions shrink, reduced current handling capabilities further challenge CMOS, necessitating novel circuit design approaches for the THz domain. By leveraging the plasma characteristics of electron channels in CMOS transistors, this study explores a potential solution for THz signal amplification. Key mechanisms in plasma wave amplification within a continuum transistor array (CTA) formed by 28 nm fully depleted silicon-on-insulator (FD-SOI) CMOS transistors are investigated. A hydrodynamic transport model combined with Pierce's theory is presented to describe plasma wave propagation along the CTA. Simulations of gated amplifiers demonstrate the potential for THz signal amplification in advanced fabrication nodes. Finally, a proof-of-concept plasma wave amplifier operating at 700 GHz has been designed and fabricated, exhibiting amplification along the plasma wave propagation path.

eess.SY↗

arXiv2026

Super-resolution ranging using a sub-terahertz self-injection-locked frequency-modulated radar

Sub-terahertz (sub-THz) and terahertz (THz) frequency-modulated continuous-wave (FMCW) radars have opened a plethora of scientific and industrial applications, especially in the imaging field. While strong candidates for sub-THz/THz FMCW radar imagers are implemented using photonic methods, there is a desire to achieve the full integration and portability that only electronics can offer. However, integrated electronic sub-THz/THz FMCW radars have significantly lower bandwidth (< 100 GHz) than photonic-based radars, restricting the radar range resolution to the millimeter scale (> 1.5 mm). In addition, the electronic FMCW radar's broad bandwidth comes with increased transmitter phase noise, consequently degrading the radar range accuracy. Here, we present a sub-THz fully-integrated autodyne frequency-modulated (AFM) radar utilizing a self-injection locking (SIL) mechanism that fundamentally overcomes the aforementioned challenges of FMCW radars. The AFM radar supports an exceptionally wide effective bandwidth extending into the terahertz sweep range by forming an intermediate frequency comb spectrum in a quadratic receiver, unlocking the path for super-resolution ranging. Furthermore, SIL significantly reduces the transmitter's phase noise, allowing high-accuracy range measurements. We theoretically describe and experimentally demonstrate the SIL operation of the AFM radar. The proposed radar experimentally achieves sub-millimeter range resolution and a range accuracy of < 0.002%, enabling the imaging of covered printed letters with micrometer features.

eess.SP↗

arXiv2024

Post-resonance reflections break the loss-vs-phase-resolution trade-off in microwave electronics

Precise phase control of microwaves and millimeter waves is critical for today's wireless communication and signal processing electronics. For decades, achieving even modest phase-shifting resolution has demanded a complex mix of transistor switches and passive electromagnetic structures. These true-phase delay, true-time-delay or quasi-true-time-delay circuits operate near resonances that heavily attenuate and distort signals, limiting transmission bandwidth. Despite numerous attempts, passive phase shifters have remained lossy and incompatible with high-channel-capacity beamforming, irrespective of the semiconductor fabrication process. In this article, we introduce a mechanism whereby waveguide reflectors based on coupled resonances can be reprogrammed to evade loss. Central to their operation is that loss from internal resonances is confined to low frequencies, while at high frequencies, their reflectivity is maximized and broadband phase variations, induced by those resonances, still persist. Since performance in the low-loss post-resonance spectrum is largely agnostic to the number of switches, ultra-fine digital tuning is possible. This breaks the historical tradeoff between loss and precision to achieve resolution surpassing state-of-the-art integrated circuits by over three orders (bits) of magnitude. The device does not distort the transmitted signal and consumes no power. Moreover, the chip occupies a sub-wavelength footprint in a Complementary Metal Oxide Semiconductor platform. This makes it an optimal candidate for seamless integration in on-chip multi-gigabit data links, radio astronomy transceivers and control hardware for millimeter-wave qubits.

eess.SP↗

arXiv2020

Heartbeat-Based Synchronization Scheme for the Human Intranet: Modeling and Analysis

Sharing a common clock signal among the nodes is crucial for communication in synchronized networks. This work presents a heartbeat-based synchronization scheme for body-worn nodes. The principles of this coordination technique combined with a puncture-based communication method are introduced. Theoretical models of the hardware blocks are presented, outlining the impact of their specifications on the system. Moreover, we evaluate the synchronization efficiency in simulation and compare with a duty-cycled receiver topology. Improvement in power consumption of at least 26% and tight latency control are highlighted at no cost on the channel availability.

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