Design of Compact Reflection-Type Phase Shifters With High Figure-of-Merit

Abstract

This paper presents reflection-type phase shifters (RTPSs) with very high figure-of-merit (FoM) and low insertion-loss variation, achieving up to 360 relative phase shifts. Two compact topologies are proposed. They were implemented at the working frequency of 2 GHz on a printed circuit board technology. The reflection loads are based on the use of one transmission line loaded by varactors, forming L-or -type networks. An automatic procedure is given to design the electrical length and the characteristic impedance of the transmission line of the reflection loads as well as the output impedance of the 3-dB branch-line coupler in order to get phase shifters with the highest possible FoM. Measurement results of the first L-type network RTPS showed a relative phase shift of 201 for only 0.54 dB 0.09 dB of insertion loss, leading to a FoM of 319 /dB. A relative phase shift of 385 was achieved for the -type network RTPS with insertion loss of only 0.98 dB 0.58 dB, leading to an FoM of 246 /dB. In both cases, simulation and measurement results fit very well. Moreover, the return loss over a 10% bandwidth is always better than 10.9 dB for the first RTPS and better than 12.3 dB for the second one, respectively. The comparison with previous works shows more compact reflection loads with electrical performance equal to the state-of-the-art.Index Terms-Branch-line coupler, figure-of-merit (FoM), reflection-type phase shifter (RTPS), varactor.

In‐band phase deviation minimization method for wideband tunable phase shifter

“…In References 4 and 5, a high phase shift range (PSR) has been achieved by modifying a hybrid coupler arm and reflection load; however, IBPD error is high. Similarly, the tunable phase shifter is designed by controlling coupling coefficient of coupled with varactor diode .…”

“…In Reference , the coupled line where varactor was connected at the center point achieved 360° PSR; however, IBPD error is higher than ±20°. From the literature reviews, it can be concluded that conventional RTPS has drawbacks such as limited BW in terms of IBPD error and insertion loss (IL) variations …”

“…Tunable phase shifter with minimum in‐band phase deviation (IBFD) error over wide bandwidth (BW) is highly desirable in practical applications such as beamforming network and self‐interference cancellation circuits . The phase shifters can be practically realized using different concepts including vector modulator, switched or reflection‐type phase shifter (RTPS) . Because the switched‐type phase shifters provide discrete phase steps, this type of phase shifter requires multiple stages to obtain small phase steps.…”

“…1,2 The phase shifters can be practically realized using different concepts including vector modulator, switched or reflection-type phase shifter (RTPS). [3][4][5][6][7][8] Because the switched-type phase shifters provide discrete phase steps, this type of phase shifter requires multiple stages to obtain small phase steps. Therefore, the RTPS is the most common type of tunable phase shifter because of high return loss (RL) and simple design.…”

“…From the literature reviews, it can be concluded that conventional RTPS has drawbacks such as limited BW in terms of IBPD error and insertion loss (IL) variations. [4][5][6][7][8] In this article, a novel RTPS design method is demonstrated to achieve minimum IBPD error with high PSR over wideband operating BW by using coupled line and varactor diode. Because the frequency dependence of varactor diode has a strong influence in IBPD error in overall BW, the proposed method uses the measured frequency-dependent capacitance of varactor diode in the analysis to obtain circuit parameters for minimum IBPD error and high PSR.…”