Raghu K. Settaluri

Compact folded line rat-race hybrid couplers

A new, compact folded line configuration for rat-race hybrid couplers is proposed. Simple design equations are presented for the single and double C-section folded line structures. The new configuration exhibits a four- to fivefold reduction in footprint as compared to the conventional rat-race configuration. The design is validated both by using the full-wave electromagnetic simulator and with measurement.

Design of compact multilevel folded-line RF couplers

A new design methodology for compact multilevel multiconductor folded-line couplers is presented in this paper. The approach is based on a general network representation of folded-line structures as interconnected coupled lines in a multilayered environment. Simple design equations are presented for compact directional couplers using two-level C-sections, and branch-line hybrids with single and cascaded C-sections. The new folded-line couplers exhibit a significant reduction in foot print compared to the conventional designs. The directional and hybrid folded-line coupler designs are validated by full-wave electromagnetic simulation. Also, a 3-dB branch-line hybrid using three folded-line sections is fabricated. The measured response is found to be in good agreement with the proposed theory.

Design of compact multilevel folded-line bandpass filters

A simple design methodology for compact multilevel multiconductor folded-line bandpass filters is presented in this paper. Several new compact folded-line filter topologies in single, as well as multilevel environments are proposed. Simple closed-form design equations are presented for the extraction of an equivalent coupled transmission line representing the folded-line filter section. The folded-line filter designs are validated by full-wave electromagnetic simulation, as well as by measurement for a four-section maximally flat four-coupled-line bandpass filter. The new folded-line filters exhibit a significant reduction in footprint compared to conventional designs.

Compact multi-level folded coupled line RF couplers

A new design methodology for compact folded line directional couplers in a multi-layer medium is presented. Multi-layer coupled line and branch line couplers are realizable as embedded passives in RF and mixed signal modules. Examples of two layer structures are included to demonstrate the design techniques.

A novel toroidal inductor structure with through-hole vias in ground plane

This paper presents a new toroidal inductor topology that can be realized in microstrip or stripline configuration. The toroidal structure comprises two sets of mutually isolated multiple-coupled lines that are connected by vias through a ground plane. This geometry facilitates a simple equivalent-circuit model for accurate analysis or synthesis of the component. A comparison between the new toroidal structure and the conventional spiral inductor topology shows good improvement in quality factor and a footprint reduction over 300%. The toroidal designs are validated by full-wave electromagnetic simulation, as well as by measurement for a two-turn toroidal inductor in microstrip configuration.

Compact multi-level folded-line bandpass filters

A simple design methodology for compact multi-level, multi-conductor folded-line bandpass filters is presented. Several new folded-line filter topologies are proposed. Simple closed-form design equations are presented for the extraction of an equivalent coupled-line representing the folded-line filter section. The new folded-line filters exhibit a significant reduction in footprints compared to the conventional designs.

A broadside-edge-coupled vialess balun

This paper presents the design procedure for a new two-level vialess balun configuration. Simple design equations are reported for designing the impedance transforming balun in broadside-edge-coupled configuration. The balun is realized in a six-coupled line two-layer topology with no ground connections and interconnecting vias. The simulated results are validated by full-wave electromagnetic simulation and found to be in good agreement.

EM based design of square-ring vialess bandpass filters

A simple technique for the design of new, vialess square-ring bandpass filters is presented. The proposed technique is based on the full-wave electromagnetic simulation of a single filter section with variable offset distance to realize a wide range of bandpass filters with flexible specifications at any given center frequency. The new, multilayered filter configurations are vialess in nature, taking advantage of the broadside coupling between different layers for simple fabrication. Two- and three-resonator Chebyshev bandpass filters with 20% and 10% bandwidth are designed at a center frequency of 2 GHz and the theoretical response is validated by measurement. Due to the EM based design approach, the proposed technique offers a high degree of accuracy. These new configurations are suitable for a variety of multilayered fabricational technologies.