K‐band 0/180° balanced phase shifter with dc‐offset cancellation

Abstract

K-band 0°/180°phase shifter MMIC based on balanced structure which can be applied to BPSK or QPSK modulator with dc-offset cancellation is presented. The proposed balanced phase shifter consists of four Lange couplers, two quarter-wave transmission lines and four switches for open and short terminations. The proposed structure implemented in GaAs 0.15-µm low noise pHEMT process ensures stable 0/180°phase shift while common-mode signals due to the mismatch in reflections by open and short are fed to the isolation port. The proposed phase shifter is verified by the phase shift of 179 ± 1.5°with the insertion loss of 4.5 ± 0.8 dB from 17.5 to 22.5 GHz. The fabricated phase shifter size is 2.2 × 2.85 mm including test pads.Introduction: Phase shifters are one of the most widely used components in microwave applications, such as phased-arrays and communication systems. For reliable system performances, phase shifters must generate a desired relative phase shift with low insertion loss variation and good return characteristics. Thus, there have been many techniques such as a reflection type phase shifter with series and parallel LC terminating circuits [1], vector-sum based phase shifter [2] and modified rat-race structure with the Lange coupler [3]. In addition, 0/180°phase shifters configured with the combinations of directional couplers, Wilkinson dividers, or 3-dB couplers are used as BPSK modulators [4,5]. However, these structures undergo the dc-offset problem [1,2] or degradation in return characteristics [3] by common mode signals returning to the input owing to the mismatch in reflective circuitry. Thus, a new balanced phase shifter structure that generates stable 0/ 180°phase shift and cancels unwanted common-mode signal which results in dc-offset is proposed.

Absorptive K-Band Bandpass Filter Using a Balanced Recursive Structure

“…Since the high power capability and reliable performance must be ensured for a satellite payload, a reflection type phase shifter with a wideband Lange coupler was designed. The detailed characteristics of the phase shifter are well-described in [13,14] and are thus omitted from this article. Furthermore, to compensate for the loss of the input and output passive networks connected with the cavity BPFs, a variable gain amplifier was adopted in this work despite not being mandatory for configuring the proposed structure.…”

K‐band reconfigurable 4 × 4 balanced power amplifier for flexible satellite communication applications

“…The measured output power and power‐added efficiency (PAE) characteristics of the single HPA at 21 GHz are shown in Figure . Also, K‐band 0/180° balanced phase shifter MMICs from were adopted as the phase inverters for accurate 0° and 180° phase shift. To verify the reconfigurable operations of the proposed balanced structure as summarized in Tables and , A is used as the input port and the maximum output power was measured for each case.…”

Reduced Subthreshold Characteristics and Flicker Noise of an AlGaAs/InGaAs PHEMT Using Liquid Phase Deposited TiO2 as a Gate Dielectric

“…The performances of GaAs-based pseudomorphic high-electron-mobility transistors (PHEMTs) have drastically been improved, and have already been extensively used in both low-noise and high-power applications at microwave and millimeter-wave frequencies [ 1 , 2 , 3 , 4 ]. However, microwave device manufacturing is still being challenged to achieve high uniformity, high yield, and reliable stability.…”