Wideband Phase Shifter Research Articles

Design of wideband phase shifter with edge-coupled semi-elliptical lines

The analysis and design of a wideband phase shifter using semi-elliptical edge-coupled structure is presented. An elliptical defected ground plane at the bottom layer is also incorporated to increase the coupling coefficient and operating bandwidth. Even and odd mode analysis has been performed and sets of design graphs are formulated to facilitate the design of the phase shifter on substrate with dielectric constant of 2.2 and 3.38. The differential phase shift is controlled by the coupling factor while the operating frequency is determined by the physical dimensions. Both simulation and measurement results show that the proposed design exhibits wideband characteristic with a phase deviation within ±4°, an insertion loss less than 1 ​dB and a return loss better than 10 ​dB. The achievable bandwidth is more than 2.4 : 1 for coupling factor of 5 ​dB which gives a differential phase shift of 80°.

Dual-Band Filtering Differential Phase Shifter Using Cascaded Wideband Phase Shifter and Bandstop Network With Two Same Phase Shifts

This letter proposes a new design method of dual-band filtering differential phase shifter using cascaded wideband phase shifter and bandstop network. After cascading the bandstop network, the phase shift characteristic of the initial wideband filtering differential phase shifter remains unchanged, while its wide passband is divided into dual subpassbands. Compared with traditional dual-band-filter-based topology, the proposed cascaded one features the advantage of independently controlled phase and amplitude responses, and can achieve the same phase shifts in two passbands that conventional one cannot. For verification, a dual-band differential phase shifter with two same phase shifts of 90° is designed, fabricated, and measured. Simulated and measured results show good agreement.

Filtering phase shifter with wide bandwidth and multiple transmission zeros

A wideband filtering phase shifter is proposed using a cascaded single line and coupled line as a shunt stub of the centre-coupled line. Such kind of a shunt stub provides the possibility to achieve wideband impedance matching, wideband phase shift, and multiple controllable transmission zeros (TZs) at the same time. The coupling between the shunt stubs of the practical layout can generate extra TZs and enhance the frequency selectivity. Compared with the state-of-the-art designs, the proposed one has wider bandwidth, more TZs and medium size, and the former cannot juggle bandwidth and size. Two prototypes at 1.76 GHz are designed with the relative operating bandwidth for 45°±3° (90°±4.2°) phase shift of 75% (76%), five TZs and the minimum return loss of 14.7 dB.

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

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 and insertion loss of . The synthesised, simulated, and measured results are in good agreement with each other.

Wideband and Dispersion Immune Microwave Photonic Phase Shifter With Tunable Optical Carrier to Sideband Ratio

A wideband microwave photonic phase shifter (MPPS) based on a dual-polarization dual-parallel Mach–Zehnder modulator (DP-DPMZM) is proposed and experimentally demonstrated. The proposed system has the features of chromatic dispersion (CD) immunity and tunable optical carrier to sideband ratio (OCSR), which can realize long fiber transmission distance with improved power efficiency. It is realized by carrier suppress double sideband (CS-DSB) plus optical carrier (OC) modulation at two orthogonal polarization states. The phases of output RF signals can be tuned continuously and independently by controlling the phases of the OCs. The experiment results show that the continuous 360° phase shifts of output RF signal over 5–25 GHz are both realized in the cases of back-to-back and fiber transmission. No CD-induced power fading and phase severe shaking of the RF signals appear after the dispersion compensating fiber (DCF) of −331 ps/nm at 1545 nm transmission. By optimizing the OCSR of the system, the output RF power efficiency of the proposed scheme realizes significantly improvement when input RF powers and output optical powers are both fixed. The possibility of generating frequency doubling signal is also verified.

Wideband Phase Shifters With Miniaturized Size on Multiple Series and Shunt Resonators: Proposal and Synthetic Design

In this article, a new class of wideband phase shifters with very compact size, large phase shift value, low insertion loss (IL), and low cost are presented and developed. The proposed phase shifter consists of N series and shunt resonators, which can achieve the magnitude and phase shift bandwidth of more than 120% thanks to N transmission poles. Besides the wideband property, the proposed phase shifter is able to achieve a small size of nearly 1/10 guided wavelength (λg), which has a size reduction of more than 90% as compared with conventional wideband phase shifters on printed circuit board (PCB). Meanwhile, insertion phases for the both series and shunt resonators are zero at their resonant frequencies; thus, the length of reference line can be also greatly reduced. What is more, a detailed synthesis method with closed-form equations is presented and employed to determine all circuit parameters of the proposed phase shifter with the specified in-band return loss (RL), phase shift value AΦ, and resonator number N. To validate the design concept, three design examples of 90° and 180° phase shifters on N = 3 and N = 5 are synthesized and tested. Theoretical, simulated, and measured results are in a fairly close agreement. In particular, the proposed phase shifters feature very low IL. The measured maximum in-band IL is only 0.38 dB for N = 3 (AΦ = 90°) and 0.50 dB for N = 5 (AΦ = 180°).

Compact Multi-Wideband Array for Millimeter-Wave Communications Using Squint Beams

Millimeter-wave (mmWave) cellular systems leverage the hybrid analog-digital structure to balance the costs and the capacity performance by using fewer Radio Frequency (RF) chains and the spatial sparsity of the channel. Besides, a more broadband system is the natural outgrowth of the gigantic frequency resource in mmWave band. However, it becomes precarious when the hybrid structure is extended to the wideband systems as the wideband phase shifters are used in the array. In this article, a multi-wideband planar array structure using the concept of Sierpinski carpet fractal is proposed, which exploits the beam squinting property instead of forming several independent beams through an existing hybrid structure. Moreover, multi-subarray can form a larger antenna array without additional costs of phase shifters for the wider range of values. First, we derive several properties of the steering beams from a wideband linear array. Then, we exploit the beam squinting property of the planar arrays employing wideband ideal phase shifters to form multi-beam. The functionality of the phase shifters in an array is simplified by a set of wideband cells connected in series. The maximum cell number needed in the array is derived, and during this derivation, we find a flaw of the beam squinting method. Finally, we present numerical results on the performance of the proposed arrays with the proposed algorithm, based on a cellular scenario of one base station (BS) and multi-user, where the BS has four subarrays and each user has one subarray.

Single-layer wideband differential phase shifter using high-order multimode resonator structure

In this paper, a new strategy for the design of a single-layer wideband phase shifter is proposed. The phase shifter employs the 7th order multimode resonator and does not require any coupling structure. Assuming a specific return loss (e.g. 15, 20 and 25 dB), the phase shifter is analyzed for a variety of phase shifts (e.g. 45° to 270°) in differential mode. To validate this design, a wideband phase shifter with phase shift of 90° ± 4.4° is fabricated in the frequency range of 2.2–7.35 GHz, which implies 107.8% fractional bandwidth. The fabricated phase shifter has a return loss of S11<-17.27dB and an insertion loss of S21>-1.28dB. The synthesized, simulated, and measured results are in good agreement with each other.

A Compact Wideband Phase Shifter Using Slotted Substrate Integrated Waveguide

A compact phase shifter using substrate integrated waveguide (SIW) with two slots is proposed in this letter. The wideband phase shift is mainly caused by the opposite phase shift slopes produced by the slots and the microstrip delay lines over a wide frequency range. Furthermore, the wide phase shift range (−90° to 90°) can be achieved and be with the same reference line. Compared with the state of the arts, the proposed one gives consideration of the wide bandwidth, wide phase shift range, simple and compact size, and easy-to-make structure, while the SIW counterparts just consider part of the above features. Five prototypes covering the frequency of 26 GHz are designed with the operating bandwidth for 90° ± 5° (−45° ± 2.5°, 45° ± 2.5°, and 90° ± 5°) phase shifter of 26.6% (29.2%, 35.8%, and 39.3%) and the size of $2.29\lambda _{g}^{2}$ ( $2.42\lambda _{g}^{2}$ , $2.71\lambda _{g}^{2}$ , and $2.86\lambda _{g}^{2}$ ; $\lambda _{g}$ is the guided wavelength at the center frequency $f_{0}$ ).

Balanced Wideband Phase Shifters With Wide Phase Shift Range and Good Common-Mode Suppression

This paper proposes a class of balanced wideband phase shifters with wide phase shift range and good common-mode (CM) suppression. Both the balanced filtering units in the reference and main branches consist of horizontal half-wavelength branches and vertical quarter-wavelength loaded stubs but with dissimilar sizes. The differential-mode (DM) section of these two units can achieve ( $2N + 1$ )th-order Chebyshev amplitude response while with discrepant phase characteristics, which can be utilized in the design of balanced phase shifters with large phase shift. As another interesting feature, the proposed balanced filtering unit functions as the conventional branch-line bandstop response in CM, and its frequency selectivity can be further enhanced by using the so-called signal-interference method. The proposed balanced wideband phase shifters have the advantages of wide phase shift range, low phase deviation, high level and wide range for CM rejection in both two branches. The 30°, 60°, 90°, 120°, 150°, and 180° balanced phase shifters are then studied and designed. As the typical examples, 30°, 90°, and 180° phase shifters are designed, fabricated, and measured. The 30° and 90° phase shifters have a fifth-order Chebyshev response, while the 180° phase shifter is of fifth-order and third-order Chebyshev responses in the reference and main branches, respectively. The measured results show that the phase shift values are 30.14° ± 2.2°, 90.75° ± 4.05°, and 180.1° ± 5.5°, the phase shift bandwidths are 73%, 68.5%, and 66.8%, and the CM rejections are −23.3, −22, and −14.6 dB, respectively.

An S-Band CMOS 6-Bit Vector-Sum Phase Shifter with Low RMS Phase Error Using Frequency-to-Voltage Converter Feedforward Loop

In this paper, a wideband full-360o phase shifter with 6 bits of accuracy has been designed and simulated with minimal root mean square (RMS) phase error. The proposed phase shifter deployed a feed forward path including a frequency-to-voltage converter (FVC) to minimize the mismatch in quadrature generation to eventually reduce the RMS phase error for S-band (2–4[Formula: see text]GHz) applications. The designed phase shifter in 180[Formula: see text]nm CMOS technology achieves an RMS phase error in the range of 0.607–1.18∘ with [Formula: see text][Formula: see text]dBm input signal over 2–4[Formula: see text]GHz frequency band. With lower input signal of [Formula: see text][Formula: see text]dBm, the RMS phase error is 0.621–1.34∘ for 2–4[Formula: see text]GHz input frequency. The proposed phase shifter shows an RMS amplitude error less than 0.41[Formula: see text]dB over 2–4[Formula: see text]GHz frequency. The 1-dB compression point ([Formula: see text]) of the proposed phase shifter is [Formula: see text][Formula: see text]dBm. The proposed wideband phase shifter draws 32 mA from 1.8 supply voltage. It occupies an active area of only 0.025[Formula: see text]mm2, due to active design without any inductor.

Balanced Wideband Phase Shifters With Good Filtering Property and Common-Mode Suppression

In this paper, a class of balanced wideband phase shifters with good filtering property and common-mode (CM) suppression is proposed, synthetically designed, and implemented. Unlike the conventional coupled-line reference branch one, the proposed balanced phase shifter has its T-shaped structure in both of main and reference branches, so as to achieve superior passband selectivity and CM rejection simultaneously. The synthesis method is then presented to design the proposed balanced wideband phase shifters with the prescribed phase shift value, passband ripple, maximum phase deviation, and fabricated bandwidth. The 30°, 45°, 60°, 75°, and 90° balanced phase shifters are theoretically designed and demonstrated. To validate the design method, two prototypes with different fractional bandwidths (FBWs) and phase shift values (Case 1: FBW = 66.7%, typical phase shift value is 30°; Case 2: FBW = 55.6%, typical phase shift value is 90°) are designed, fabricated, and measured. The synthesized, simulated, and measured results are found in good agreement with each other.

Wideband Dual-Polarized Multiple Beam-Forming Antenna Arrays

Wideband multibeam antenna arrays based on three-beam Butler matrices are presented in this paper. The proposed beam-forming arrays are particularly suited to increasing the capacity of 4G long-term evolution (LTE) base stations. Although dual-polarized arrays are widely used in LTE base stations, analog beam-forming arrays have not been realized before, due to the huge challenge of achieving wide operating bandwidth and stable array patterns. To tackle these problems, for the first time, we present a novel wideband multiple beam-forming antenna array based on Butler matrices. The described beam-forming networks produce three beams but the methods are applicable to larger networks. The essential part of the beam-forming array is a wideband three-beam Butler matrix, which comprises quadrature couplers and fixed wideband phase shifters. Wideband quadrature and phase shifters are developed using striplines, which provide the required power levels and phase differences at the outputs. To achieve the correct beamwidth and to obtain the required level of crossover between adjacent beams, beam-forming networks consisting of augmented three-beam Butler matrices using power dividers are presented to expand the number of output ports from three to five or six. Dual-polarized, three-beam antenna arrays with five and six elements covering LTE band are developed. Prototypes comprising beam-forming networks and arrays are tested according to LTE base station specification. The test results show close agreement with the simulation ones and compliance with LTE requirements. The designs presented are applicable to a wide range of wideband multibeam arrays.

High-Resolution Wideband Phase Shifter With Current Limited Vector-Sum

In this paper, a 360° wideband phase shifter with current limited vector-sum and digital calibration is presented to achieve high phase resolution and low amplitude error. The output phase is synthesized from quadrature vectors by variable gain amplifiers (VGAs) with current-digital to analog converters (I-DACs). Several VGA control algorithms are investigated to find trade off among phase error, amplitude error, and power consumption. A current limited vector-sum method is proposed to achieve low phase error, amplitude error, and power consumption, simultaneously. Quadrant selection is realized by the reconfigurable VGAs without extra switch circuit. Coarse- and fine-scaling of quadrature vector amplitude is accomplished by I-DACs with segments of different current weights. The phase non-linearity is calibrated using digital pre-distortion to further improve the phase error. To verify the mechanism mentioned above, a fully integrated 10-bit phase shifter operating at 3–7 GHz with current limited vectors is implemented and fabricated in a conventional 40–nm CMOS technology. It exhibits root mean square (RMS) phase error of 0.41°–1.67°, RMS amplitude error of 0.42–0.89 dB, and effective phase resolution of 1.406° (8-bit) from 3–7 GHz. The core circuit occupies 0.19 mm2 and draws 11.4–16.2 mW from 1.1 V supply.

Compact Equal-Width Equal-Length Phase Shifter With Slow-Wave Half-Mode Substrate Integrated Waveguide for 5G Applications

The emerging fifth-generation (5G) wireless and mobile communications demand high-performance phase shifters to enable the multi-channel transmit/receive systems with phase control ability. In this work, a size-miniaturized wideband phase shifter based on slow-wave half-mode substrate integrated waveguide (SW-HMSIW) is presented. The proposed SW-HMSIW is consisting of conventional HMSIW section and periodically-patterned non-uniform microtrip polyline unit cells. Patterning polyline unit cells in HMSIW can effectively enhance the product of the equivalent permittivity and permeability of SW-HMSIW, so that the slow-wave effect can be exhibited and its associated size reduction will be further achieved. Moreover, lengths and widths of segments of the proposed polyline unit cell can influence the equivalent permittivity and permeability of the SW-HMSIW, and consequently change its phase constant and cutoff frequency. Hence, for a SW-HMSIW with a fixed physical length, an electrical length variation, i.e, phase shift, can be achieved as segments of the polyline employ various lengths or widths. Based on this principle, a wideband equal-width equal-length SW-HMSIW phase shifter is implemented. Measured results are in good agreement with simulated ones, with a phase shift of 90.5 ± 3 degree and a fractional bandwidth of 43.0% achieved. Compared with some similar reported works, the proposed one shows a size reduction more than 80% as well as good magnitude and phase deviations performance. Moreover, its miniaturized size and equal-width equal-length structure make it suitable for the complex multi-channel modules and networks of the 5G applications.

Proposal and Synthesis Design of Wideband Filtering Differential Phase Shifters With a Pair of Out-of-Band Transmission Zeroes

In this paper, a new class of wideband filtering phase shifters with a pair of controllable out-of-band transmission zeroes is presented for the first time. The proposed wideband filtering differential phase shifter consists of two stub-loaded multimode resonators (SLMMR) in the main and reference branches, which can provide a constant phase shift and self-realized generalized Chebyshev filtering function with controllable transmission zeroes by properly setting the impedance ratio $R_{\mathrm {z}}$ of the loaded stub. On the one hand, the prescribed phase shift value, phase deviation, and phase shift bandwidth are deduced that basically dominated by resonant modes of SLMMR together with electrical lengths of the phase-shifting lines. On the other hand, the phase properties of transmission zeroes are systematically investigated to demonstrate that they arouse little effect on the phase shift performance, but highly improve the frequency selectivity in theoretical analysis. Based on the presented synthesis method which simultaneously considers wideband phase shift and bandpass filtering function, the circuit parameters of the entire proposed phase shifter can be synthesized with prescribed phase shift value, phase deviation, bandwidth, return loss, and transmission zero positions. Besides, the phase shift and return loss bandwidth can be determined in the design process. As design examples, two 90° wideband filtering phase shifters with different specifications are synthesized, designed, and fabricated to validate our proposed approach.

Wideband and Ultrawideband Phase Shifter Designs Based on Low-Pass/Bandpass/High-Pass Networks

This paper presents the design of wideband and ultrawideband 90° phase shifters using coupled-line sections and low-pass/bandpass/high-pass networks with inductors and capacitors. By relaxing the tight-coupling requirement, the proposed phase shifters are realized with much easier fabrication process. It is demonstrated how the embedded low-pass/bandpass/high-pass networks make the phase shifters wideband. The fabricated phase shifters with low-pass, bandpass, and high-pass networks using discrete elements achieve the operating bandwidths of 44%, 83%, and 107%, respectively. Later, discrete elements are replaced by their equivalent short and open microstrip lines to make the system monolithic and more reliable, especially at higher frequencies. The measured results show approximately equal bandwidths of 40%, 87%, and 94% for the phase shifters with low-pass, bandpass, and high-pass networks, respectively.

Compact and Wideband MMIC Phase Shifters Using Tunable Active Inductor-Loaded All-Pass Networks

To address the challenging needs of small size, wide bandwidth, and low-frequency applicability, a novel phase shifter implementation is introduced that utilizes tunable active differential inductors within all-pass networks. The inductor tuning is used to achieve phase shifts up to 180°. A switchable active balanced-to-unbalanced transition (balun) circuit is included in front of the all-pass network to complement its phase shift capability by another 180°. In addition, the all-pass network is followed by a variable-gain amplifier to correct for gain variations among the phase shifting states and act as an output buffer. Although active inductors have previously been used in the design of various components, to the best of our knowledge this is the first time that they have been used in an all-pass phase shifter. The approach is demonstrated with an on-chip design and implementation exhibiting wideband performance for S- and L-band applications by utilizing the 0.5- $\mu \text{m}$ TriQuint pHEMT GaAs monolithic microwave integrated circuits (MMIC) process. Specifically, the presented phase shifter $1 \times 3.95~ \text {mm}^{2}$ die area and operates within the 1.5–3-GHz band (i.e., 2:1 bandwidth) with 10-dB gain, less than 1.5-dB root-mean-square (rms) gain error and less than 9° rms phase error. Comparison with the state-of-the-art MMIC phase shifters operating in S- and L-bands demonstrates that the presented phase shifter exhibits a remarkable bandwidth performance from a very compact footprint with low-power consumption. Consequently, it presents an alternative for the implementation of wideband phase shifters where all-passive implementations will consume expensive die real estate.

Anti-dispersion phase-tunable microwave mixer based on a dual-drive dual-parallel Mach-Zehnder modulator.

An optically-controlled phase-tunable microwave mixer based on a dual-drive dual-parallel Mach-Zehnder modulator (DDDP-MZM) is proposed, which supports wideband phase shift and immunity to power fading caused by chromatic dispersion. By using carrier-suppressed single side-band (CS-SSB) modulation for the local oscillator (LO) signal and carrier-suppressed double side-band (CS-DSB) modulation for the input signal, no vector superposition for the same output microwave frequency occurs, making the system immune from power fading caused by chromatic dispersion. Phase tuning is achieved by shifting the phase of the LO signal, and direct electrical tuning of the wideband microwave input signal is avoided, thus supporting large working bandwidth. A phase-shifted down-conversion experiment is carried out, where a phase shift with 0 ~390° and down-conversion are achieved with a phase variation of less than 5° and power variation less than 3.5 dBm when the input signal sweeps between 12 ~16 GHz. The mixer is simple and power-efficient since it uses a single compact modulator, and does not require any optical filters. No power notches are observed in the output microwave spectrum, proving that the dispersion-related frequency-selective fading is mitigated.

Wideband Phase Shifter in Groove Gap Waveguide Technology Implemented With Glide-Symmetric Holey EBG

A wideband phase shifter in $U$ -band realized in groove gap waveguide (GGWG) technology is presented as a good solution to be integrated in antenna feed structures. The GGWG is implemented by glide-symmetric holes to reduce manufacturing complexity. The design is also proposed to be mechanically variable by changing the height of the dielectric slab used to change the phase. Experimental results evidence the potential of this solution.