Artificial-Synthesized Edge-Coupled Transmission Lines for Compact CMOS Directional Coupler Designs

Abstract

This paper presents artificial-synthesized edgecoupled transmission lines (TLs) based on complementary metaloxide semiconductor (CMOS) technology. The artificial coupledline (CL), the so-called the complementary-conducting-strip coupled line (CCS CL), consists of the unit cell and is meandered in the 2-D plane. The unit cell, whose dimensions are much smaller than the guiding wavelength at the operating frequency, provides five structural parameters for CL syntheses. The synthesized CLs, which are fully characterized by using theoretical and experimental procedures, reveal the following unique guiding properties. First, the coupling coefficient ( ) can be 7.7% higher than that of the meandered conventional edged-coupled TLs. Second, the evenand odd-mode propagation constants can be synthesized as identical at the same time. Two backward-wave directional couplers for achieving the tight coupling and high directivity are designed by incorporating artificial CCS CL. Two prototypes are fabricated by the standard 0.18-m CMOS technology, occupying the chip areas of 120.0 m 240.0 m. The measured results show that the isolation is higher than 25.0 dB from 10.0 to 40.0 GHz with a coupling of 14.4 dB. On the tight coupler design, the through and coupling are 4.65 0.15 dB from 30.0 to 40.0 GHz with an amplitude imbalance of less than 0.3 dB.

Synthesis of Multiconductor Microstrip Lines Operating in Normal Modes / Daugialaidės Mikrojuostelinės Linijos, Veikiančios Normaliųjų Bangų Režimu, Sintezė

“…Synthesis problems are of particular interest for creating CAD systems for microwave devices, and therefore many researches were intensively solving them in the past decade (Rawat, Ghannouchi 2009;Chiang et al 2009;Yioultsis et al 2003;Lee, Tsai 2009). In case of the MCML operating in a normal mode, synthesis is an iterative process of finding topological dimensions of an MCML, which restricts propagation to a single normal mode in the line when specified modal voltages are applied.…”

“…In the absence of such technique, devices are typically designed using extensive software simulations where high-frequency simulators (mostly commercial) are used for determining the required design parameters for a good coverage (Rawat, Ghannouchi 2009;Chiang et al 2009;Yioultsis et al 2003). This paper proposes a synthesis technique for the MCML operating in a normal mode.…”