A method for dividing ratio equalization of power dividing/combining circuits used in a power amplifier

Abstract

Most power amplifiers with several FETs in parallel utilize a two‐way power dividing/combining circuit of asymmetric structure. The asymmetric structure provides unequal power dividing/combining characteristics. In this paper the power dividing/combining ratio as a function of the structure is calculated by using the method of moments and is verified by experiments. The relation between unequal power dividing/combining characteristics and the equal phase plane of current flow is also shown. Finally, a method of equalizing the power dividing/combining ratio by making branch line impedances unequal is presented. © 1999 Scripta Technica, Electron Comm Jpn Pt 2, 82(7): 16–22, 1999

Ku‐band 20‐W gaAs PHEMT high‐power amplifiers using power splitting and combining circuits with asymmetric structure

“…1(a) is that symmetry of i a and i b is ruled out by the fact that the tilt angle T of the equal phase plane in the figure is 0 T 90, so that i 2 > i 1 in amplitude [3,4]. Thus, in Fig.…”

“…If the matching condition is not altered by T of the equal phase plane, Z 2 in Fig. 1(a) is given by while Z 2a and Z 2b are expressed as follows, ignoring the discontinuity in linewidth at D 2 and the effect of T [3,4]:…”

“…1(b), r and S are determined by the method of moments (EM simulation). Greater lengths l 1 and l 2 are preferable, since I becomes smaller, resulting in decreased inequality of the splitting characteristics [3,4]. However, as a result of geometrical limitation on the FET chip size and circuit length, here l 1 and l 2 are set to 0.042 and 0.054 O, respectively.…”

“…However, partial geometric asymmetry exists in the individual two-way splitting circuit, and this causes imbalance of the splitting/combing characteristics. In order to address this problem, a two-way splitting/combining circuit with asymmetric structure, having unequal branch lines with different characteristic impedance was proposed [3,4]. However, in Refs.…”

Broadband Multi-Way Microstrip Power Dividers

“…A power divider/combiner for RF power division and combination is one of the basic passive components and applied to many microwave and millimeter wave systems and devices such as antenna feeders and power amplifiers. Constituting principle of the divider/combiner is classified roughly into two groups; (1) a branch-line type divider which consists of two or more output lines branching in parallel from an input line [1], [2] and (2) a planar circuit type one which is designed by utilizing the two-dimensional current distribution on a strip conductor pattern [3], [4]. The former type requires matching networks such as quarter wavelength transformer, because the characteristic impedance of the input line usually differs from that of the parallel combination of the output lines.…”