Millimeter-Wave On-Chip Dual-Mode Transmission Line with Low Insertion Loss and Wide Band Based on Composite Right-/ Left-Handed Theory

This article proposes a dual-mode millimeter-wave on-chip transmission line (TL) based on the composite right-/left-handed (CRLH) theory, featuring both wide bandwidth and low loss. In addition, both the right-handed (RH) band supporting the forward waves and the left-handed (LH) band supporting backward waves are realized. To address the issues of high loss and high parasitic effect in millimeter-wave range and on semi-conductor substrate, a T-type CRLH on-chip unit cell is proposed. To further reduce the transmission loss and extend the bandwidth, the circuit topology and structural realization are investigated. In addition, dual modes including the RH and LH bands are realized by analyzing the dispersion curve of the CRLH transmission line. Based on Gallium Arsenide (GaAs)-based integrated passive device (IPD) technology, a 3rd-order periodic CRLH TL ranging from 18~44.5 GHz was fabricated and measured. The proposed transmission line features a compact size of 1.3 mm × 0.55 mm including GSG (Ground Signal Ground) pads, a minimum insertion loss of 1.18 dB, and a 3 dB fractional bandwidth exceeding 90%. These measurement results demonstrate that the proposed on-chip transmission line can be widely applied in on-chip functional circuits and systems for unique electromagnetic phase characteristics. © 2024 Chinese Institute of Electronics. All rights reserved.