High-directivity compact slow-wave CoPlanar waveguide couplers for millimeter-wave applications

Design of mm-Wave Slow-Wave-Coupled Coplanar Waveguides

“…In addition to the classical structure, authors in [9] also presented two alternative topologies for added design flexibility. These topologies can include either a cut in the center of the shielding, namely Central-Cut (CC-shielding) or Side-Cut (SC-shielding).…”

“…It overcomes the aforementioned microstrip lines couplers limitations, and offers the possibility to design compact coupled-line couplers with an extra degree of freedom, leading to simpler design process and better electrical performance in terms of directivity and insertion loss. The concept is based on the coupled-slow-wave coplanar waveguide (CS-CPW) that was conceptually introduced in [9] and validated by simulation results of a backward coupler. The concept of CS-CPW was also used later in [10] to implement the matching network of a mm-wave power amplifier using a simpler topology of CS-CPW, which does not offer the same flexibility as proposed in [9] for the choice of electric and coupling coefficients, thus limiting the design possibilities.…”

mm-Wave Through-Load Switch for in-situ Vector Network Analyzer on a 55-nm BiCMOS Technology

“…Hence, it allows the designer to use small transistors, which present low input capacitances and thus smaller imaginary part of their input impedance. Finally, the 3-dB coupler is based on coupled Slow-wave CPW architecture [12]. This architecture is briefly described in the next sub-section.…”

“…The CS-CPWs take advantage of the floating shield to: (i) reduce the electrical length of the coupler through the slow-wave effect, (ii) increase the electrical coupling between the signal strips and (iii) the directivity of the coupler. This structure was firstly introduced in [12]. In this work, authors explored the performance and versatility of the structure, introducing a cut on the fingers giving the designer an extra degree of freedom.…”

Wideband mm-Wave CMOS Slow Wave Coupler

“…For example, in [1], a thin film microstrip line is used with an aggressive meandering to reduce the size of the coupler. In [2], a coupler based on the coupled slow-wave coplanar waveguide (CS-CPW) is presented, and the miniaturization is achieved by modifying the shielding ribbons. Nevertheless, none of the works addressed the modeling methodology (with a simulator) used for designing their proposed complex coupler structures, whereas customarily, an efficient and reliable modeling methodology is critical in the CMOS circuit designs.…”