Homodyne vs. Heterodyne Architectures in Sub-THz Transceivers: A Phase Noise Perspective

TL;DR

This paper compares homodyne and heterodyne transceiver architectures in sub-THz systems, showing heterodyne designs better mitigate phase noise effects at higher frequencies, thus enabling more robust wireless communication.

Contribution

It provides an analytical comparison of phase noise impact in homodyne and heterodyne architectures using a realistic model, highlighting the advantages of heterodyne designs at sub-THz frequencies.

Findings

Heterodyne architectures reduce phase noise variance by distributing frequency translation.

Heterodyne designs shift impairment from inter-carrier interference to common phase error.

Heterodyne architectures offer improved robustness at 70 GHz and 140 GHz.

Abstract

This letter examines the impact of oscillator phase noise on sub-terahertz OFDM transceiver architectures, with a focus on the comparison between homodyne and heterodyne designs. Using a Hexa-X compliant phase noise model, we analytically show that heterodyne architectures reduce the total accumulated phase noise variance by distributing frequency translation across lower-frequency oscillators under realistic phase-noise scaling laws, thereby shifting the dominant impairment from inter-carrier interference to common phase error. OFDM simulations at 70 GHz and 140 GHz demonstrate that while homodyne architectures remain competitive at mmWave frequencies, heterodyne designs provide improved robustness to phase noise at higher sub-THz carriers. These results highlight transceiver architecture as a key design lever for relaxing oscillator and phase-locked loop constraints in future sub-THz wireless systems.