Simple ladder‐like single‐layer balanced wideband phase shifter with wide phase shift range and appropriate common‐mode suppression

Abstract

In this study, a single‐layer balanced wideband phase shifter with a wide phase shift range of 45°–315° and acceptable common‐mode (CM) suppression is proposed. The main branch has a simple ladder‐like structure and the reference branch utilises a coupling structure. The main branch electrical length is constant for any desired differential‐mode (DM) phase shift. Assuming a specific return loss (e.g. 16, 20, and 25 dB), the phase shifter is carefully analysed and a design procedure is given leading to an ultra‐low phase error design. Then by making a trade‐off between the CM and DM bandwidths at the cost of higher phase error, more design solutions for the phase shifter are given. To validate both the proposed structure as well as its design procedure, a balanced wideband phase shifter with the DM phase shift of 180°±4.2° (1.851–4.017 GHz) and the CM suppression of better than 15 dB (1.81–4 GHz) is fabricated, resulting in 73.82 and 75.25% fractional bandwidth, respectively. The fabricated balanced phase shifter has a return loss of ||S11dd<−14.87thinmathspacedB and insertion loss of ||S21dd>−0.95thinmathspacedB. The synthesised, simulated, and measured results are in good agreement with each other.

A Balanced Substrate Integrated Waveguide Phase Shifter with Wideband Common-Mode Suppression

“…Table 2 lists the demonstrated performances of the proposed design and other reported microstrip and SIW phase shifters. Compared to previously reported microstrip balanced phase shifters ([ 6 , 7 , 9 ]), the proposed SIW design has narrower bandwidth, but it would be more suitable for millimetre wave application. Compared to previously reported SIW phase shifters ([ 13 , 14 , 15 , 16 , 18 , 20 , 22 ]), the proposed design features a balanced topology with wideband CM suppression.…”

“…Currently, a few balanced phase shifters have been reported [ 4 , 5 , 6 , 7 , 8 , 9 , 10 , 11 ], and all of them are microstrip designs. Several approaches have been used to design microstrip balanced phase shifters, including coupled lines with loaded transmission lines [ 4 , 5 , 6 ], two-stage branch line structure [ 7 ], cascaded three microstrip lines and two coupled lines [ 8 ], T-shaped multi-mode resonator with intermediate cascaded stubs [ 9 ], two three-end folded coupled lines with three half-wavelength microstrip lines [ 10 ], LC-based microstrip differential line with periodic T-shaped stubs [ 11 ], etc. Among them, different features have been achieved, such as compact size in [ 4 , 6 ], wideband CM suppression in [ 8 ], large phase shift range in [ 7 , 9 ], fusing filtering function in [ 5 , 10 ], and tunable phase shift in [ 11 ].…”

“…Several approaches have been used to design microstrip balanced phase shifters, including coupled lines with loaded transmission lines [ 4 , 5 , 6 ], two-stage branch line structure [ 7 ], cascaded three microstrip lines and two coupled lines [ 8 ], T-shaped multi-mode resonator with intermediate cascaded stubs [ 9 ], two three-end folded coupled lines with three half-wavelength microstrip lines [ 10 ], LC-based microstrip differential line with periodic T-shaped stubs [ 11 ], etc. Among them, different features have been achieved, such as compact size in [ 4 , 6 ], wideband CM suppression in [ 8 ], large phase shift range in [ 7 , 9 ], fusing filtering function in [ 5 , 10 ], and tunable phase shift in [ 11 ].…”

Design of broadband reconfigurable phase shifters

“…It can be estimated by R m is also a crucial factor which can improve transmission parameters. And it can be expressed as this following equation presented by 17 …”