Analysis and design of a parallel coupled‐line quadrature coupler with lumped‐elements

Abstract

PurposeThe purpose of this paper is to present a broadband parallel coupled‐line quadrature coupler implemented with lumped‐elements.Design/methodology/approachThe even‐ and odd‐mode method is used to compute the proposed coupler, and the analysis and optimization are done using the computer‐aided design tools. A design example of a broadband tunable quadrature coupler is provided.FindingsThis novel structure is clearly increasing the conductor spacing and decreasing the whole structure size, at the same time, the bandwidth is much wider.Originality/valueThis paper shows how a parallel coupled‐line quadrature coupler with lumped‐elements has been analyzed and designed, and proposes a simple and convenient method to calculate this structure. Compared with the normal parallel coupled‐line structure, the conductor spacing of this coupler is increased effectively, while the structure size is decreased. In addition, because of the tunable embedded capacitors, the bandwidth becomes much wider – a broadband up to 77 percent is achieved.