6-bit Phase Shifter Research Articles

A 1.7–2.7-GHz 4-bit Phase shifter based on packaged RF MEMS switches

This study presents a 4-bit phase shifter with a maximum phase shift degree of 75° based on packaged metal-contact single-pole double-throw (SPDT) radio frequency microelectromechanical system (RF MEMS) switches mounted on a 20 mil RO4350 substrate and assembled with its driver module on a 4-layer printed circuit board (PCB) board. Electric length of 10° and characteristic impedance of 61.7 Ω are selected for T-stub matching. Standard PCB processing makes it easy to develop and suitable for taking place of mechanical tilt employed in recent base station. Measurements indicate a maximum insertion loss of 1.37 dB at 2.7 GHz and a minimum return loss of 11.71 dB. The phase accuracy is within 1.75° at 2.7 GHz.

A Fully Integrated X-Band Phased-Array Transceiver in 0.13- SiGe BiCMOS Technology

This paper presents the design of an X-band phased-array transceiver core chip in 0.13- $\mu{\hbox{m}}$ SiGe BiCMOS technology. The system is based on the all-RF architecture and contains switches, low-noise amplifier (LNA), power amplifier (PA), and the common leg 5-bit phase shifter with loss compensation amplifiers. A distributed structure is used in the gain amplifiers design to ease the multi-stage gain roll-off in the transmit (TX)/receive (RX) paths. A distributed LNA is utilized in the RX path to achieve broadband amplification with acceptable noise figure (NF) while a stacked PA is utilized in the TX path to get high output power. In the RX mode, the receiver demonstrates a gain of $> {\hbox{25 dB}}$ , an average NF of 3 dB, an output ${ P} _{-1~{\rm dB}}$ of 6 dBm, a root mean square (rms) phase error less than 3.8 $^{\circ}$ and an rms gain error less than 1.2 dB from 9 to 11 GHz; while dissipating 352-mW dc power. In the TX mode, the transmitter demonstrates a gain of $> {\hbox{22 dB}}$ , an output ${ P} _{-1~{\rm dB}}$ of 28 dBm, an rms phase error less than 3 $^{\circ}$ , and an rms gain error less than 0.6 dB from 9 to 11 GHz; while dissipating 4.128-W dc power. The whole transceiver occupies 5.2 $\,\times\,$ 3 ${\hbox{mm}}^{2}$ chip area including the testing pads.

A SIMPLE 2×3 BEAM-FORMING NETWORK WITH A 2-BIT PHASE SHIFTER FOR FOUR-BEAM RECONFIGURATION

A simple 2£3 reconflgurable beam-forming network (R-BFN) for four-beam reconflguration application is designed and implemented. The proposed R-BFN with two input ports and three output ports consists of a 2:1 power divider, a 90 - hybrid, a 180 - hybrid and a 2-bit phase shifter. The 2- bit phase shifter has two states: one is a 180 - phase shifter (State 1); the other is a 0 - =360 - phase shifter (State 2). By introducing the 2-bit phase shifter, the constant phase difierences of three output ports can be reconflgured. When the proposed R-BFN is connected to an antenna array, a four-beam reconflguration is obtained. Simulated and measured results show that good impedance matching, high port isolation, equal power division, and constant phase difierence have been achieved simultaneously within the operation band of 2.4{2.6GHz. The capability of the proposed R-BFN to reconflgure beams is also verifled experimentally by using a 2.5GHz dipole array.

Low Insertion Loss, Compact 4-bit Phase Shifter in 65 nm CMOS for 5G Applications

This letter presents a 28 GHz low insertion loss and compact size 4-bit phase shifter in 65 nm CMOS Technology. In order to get low insertion loss and compact size, this phase shifter is composed of two types of passive phase shifters, high-pass/low-pass type and switched filter type. Various techniques are used such as triple well body-floating, gate-floating, removal of capacitance of the off-state transistor using resonant inductor, and minimized interconnection line which is based on matching network. This phase shifter has 6.36 dB of average insertion loss over the 27.5–28.35 GHz, and loss variation is about 2 dB. The return loss is higher than 12 dB, RMS phase error is 8.98 $^{\circ}$ , OIP3 is 8.1 dBm at $-$ 10 dBm input power and its core size is 636 $\mu$ m $\times$ 360 $\mu$ m. To the authors' knowledge, these results are the state of the art in CMOS passive phase shifters in K-band frequency.

Reliability Analysis of Ku-Band 5-bit Phase Shifters Using MEMS SP4T and SPDT Switches

This work presents a Ku-band microelectromechanical systems (MEMS) based 5-bit phase shifter using dc contact single-pole-four-throw (SP4T) and single-pole-double-throw switches. The design is implemented using a coplanar waveguide transmission line. Two individual 2-bit phase shifters and one 1-bit phase shifter are cascaded to develop the complete 5-bit phase shifter. The phase shifters are fabricated on 635- $\mu{\hbox{m}}$ alumina substrate using a surface micromachining process. The 5-bit phase shifter demonstrates an average insertion loss of 2.65 dB in the 13–18-GHz band with a return loss better than 22 dB and average phase error less than 0.68 $^{\circ}$ at 17 GHz. Total area of the fabricated 5-bit phase shifter is ${\hbox{4.7}}\times {\hbox{2.8}} {\hbox{mm}}^{2}$ . The reliability of the single-pole-single-throw and SP4T switches show more than 10 million cycles with an RF power of 0.1–2 W. Furthermore, reliability of the MEMS phase shifter is extensively investigated and presented with cold and hot switched conditions. To the best of our knowledge, this is the first reported MEMS 5-bit phase shifter in the literature that has undergone different reliability and qualification testing including 3-axis vibrations.

A 2.45 GHz Phased Array Antenna Unit Cell Fabricated Using 3-D Multi-Layer Direct Digital Manufacturing

This paper reports on the design, fabrication and characterization of a 3-D printed RF front end for a 2.45 GHz phased array unit cell. The printed unit cell, which includes a circularly-polarized dipole antenna, a miniaturized capacitive-loaded open-loop resonator filter and a 4-bit phase shifter, is fabricated using a direct digital manufacturing (DDM) approach that integrates fused deposition of thermoplastic substrates with micro-dispensing for deposition of conductive traces. The individual components are combined in a passive phased array antenna unit cell comprised of seven stacked substrate layers with seven conductor layers. The measured return loss of the unit cell is ${>}12$ dB across the 2.45 GHz ISM band and the measured gain is ${-}11$ dBi including all components. Experimental and simulation-based characterization is performed to investigate electrical properties of as-printed materials, in particular the inhomogeneity of printed thick-film conductors and substrate surface roughness. The results demonstrate the strong potential for fully-printed RF front ends for light weight, low cost, conformal and readily customized applications.

Enhanced dual‐circular polarised four‐arm Archimedean spiral antenna with low‐profile cavity backing

A wideband dual-circular unidirectional four-arm Archimedean spiral antenna operating from 0.6 to 2.4 GHz is presented. Without a cavity, the antenna radiates bi-directionally and the dual-circular polarisation of the spiral antenna at boresight is limited to a frequency range from 0.6 to 1.5 GHz. After adding a low-profile, 15 mm deep metallic cavity, the dual-circular polarisation at boresight is extended to more than 2.4 GHz and uni-directional radiation is realised. The four-arm spiral antenna is excited through a feed network consisting of a wideband four-way power divider and four wideband digital 2-bit phase shifters. This feed network facilitates instantaneous switching between right hand circular polarisation and left hand circular polarisation. The measured input return loss of the system is more than 10 dB for the entire two-octave bandwidth. The measured boresight gain from 0.6 to 2.4 GHz is −2.8 to 11.2 dBi and −3.1 to 8.7 dBi for RHCP and LHCP, respectively.

A Highly Integrated 1-Bit Phase Shifter Based on High-Pass/Low-Pass Structure

This letter presents a highly integrated 1-bit 90 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">°</sup> phase shifter based on high-pass/low-pass structure for 60 GHz beamforming applications using a standard 65 nm CMOS process. In order to overcome the limitation of the conventional low-pass only phase shifter, the combination of high-pass/low-pass network was utilized as a 1-bit phase shifter. By integrating a high pass network into the low-pass network with low loss single-pole single throw (SPST) switches that adapt a resistive body floating technique, the proposed phase shifter achieves average 5 dB IL and less than ±0.18 dB of insertion loss flatness and 1 dB rms amplitude error over the whole band in a small chip area of 0.16 mm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> including pads.

A high linearity X-band SOI CMOS digitally-controlled phase shifter

This paper proposed an X-band 6-bit passive phase shifter (PS) designed in 0.18 μm silicon-on-insulator (SOI) CMOS technology, which solves the key problem of high integration degree, low power, and a small size T/R module. The switched-topology is employed to achieve broadband and flat phase shift. The ESD circuit and driver are also integrated in the PS. It covers the frequency band from 7.5 to 10.5 GHz with an EMS phase error less than 7.5°. The input and output VSWRs are less than 2 and the insertion loss (IL) is between 8–14 dB across the 7.5 to 10.5 GHz, with a maximum IL difference of 4 dB. The input 1 dB compression point (IP1dB) is 20 dBm.

10–25 GHz frequency reconfigurable MEMS 5-bit phase shifter using push–pull actuator based toggle mechanism

This paper presents a frequency tunable 5-bit true-time-delay digital phase shifter using radio frequency microelectromechanical system (RF MEMS) technology. The phase shifter is based on the distributed MEMS transmission line (DMTL) concept utilizing a MEMS varactor. The main source of frequency tuning in this work is a bridge actuation mechanism followed by capacitance variation. Two stages of actuation mechanisms (push and pull) are used to achieve a 2:1 tuning ratio. Accurate control of the actuation voltage between the pull to push stages contributes differential phase shift over the band of interest. The functional behavior of the push–pull actuation over the phase shifter application is theoretically established, experimentally investigated and validated with simulation. The phase shifter is fabricated monolithically using a gold based surface micromachining process on an alumina substrate. The individual primary phase-bits (11.25°/22.5°/45°/90°/180°) that are the fundamental building blocks of the complete 5-bit phase shifter are designed, fabricated and experimentally characterized from 10–25 GHz for specific applications. Finally, the complete 5-bit phase shifter demonstrates an average phase error of 4.32°, 2.8°, 1° and 1.58°, an average insertion loss of 3.76, 4.1, 4.2 and 4.84 dB and an average return loss of 11.7, 12, 14 and 11.8 dB at 10, 12, 17.2 and 25 GHz, respectively. To the best of the authors’ knowledge, this is the first reported band tunable stand alone 5-bit phase shifter in the literature which can work over the large spectrum for different applications. The total area of the 5-bit phase shifter is 15.6 mm2. Furthermore, the cold-switched reliability of the unit cell and the complete 5-bit MEMS phase shifter are extensively investigated and presented.

Cantilever RF-MEMS for monolithic integration with phased array antennas on a PCB

This article presents the development and operation of a novel electrostatic metal-to-metal contact cantilever radio-frequency microelectromechanical system (RF-MEMS) switch for monolithic integration with microstrip phased array antennas (PAAs) on a printed circuit board. The switch is fabricated using simple photolithography techniques on a Rogers 4003c substrate, with a footprint of 200 µm × 100 µm, based on a 1 µm-thick copper cantilever. An alternative wet-etching technique for effectively releasing the cantilever is described. Electrostatic and electromagnetic measurements show that the RF-MEMS presents an actuation voltage of 90 V for metal-to-metal contact, an isolation of −8.7 dB, insertion loss of −2.5 dB and a return loss of −15 dB on a 50 Ω microstrip line at 12.5 GHz. For proof-of-concept, a beam-steering 2 × 2 microstrip PAA, based on two 1-bit phase shifters suitable for the monolithic integration of the RF-MEMS, has been designed and measured at 12.5 GHz. Measurements show that the beam-steering system presents effective radiation characteristics with scanning capabilities from broadside towards 29° in the H-plane.

Low Loss 2-Bit Distributed MEMS Phase Shifter using Chamfered Transmission Line

Objectives: The objective of this paper is to design a 2-bit DMTL phase shifter with low insertion loss, improved phase shift per dB loss with minimum number of switches. Methods/Analysis: In order to reduce the insertion loss tapered impedance section proposed previous researchers introduces impedance discontinuity at the end of the taper that introduces a fringing capacitance at the transition region which cannot be neglected while calculating the loaded line capacitance. The proposed chamfered transmission line design for phase shifter overcomes this shortcoming with a uniform high impedance line that does not have any discontinuities and causes variations of propagation constant along the length of the transmission line. The proposed design also reduces the discontinuity effects associated with step width junction and reflection is much reduced. Findings: Chamfering the corners at the contact area of switch with the transmission line reduces the discontinuity effects associated with step width junction. The achieved phase shift is 178.87o at 17GHz with an insertion loss of -0.87dB and return loss in both up, down states less than -15dB. Design and simulation results of the phase shifter with respect to pull-in voltage of the switch, RF characterization is done using Coventorware and HFSS. Keywords: Chamfered, Co-Planar Waveguide (CPW), Distributed MEMS Transmission Line (DMTL), Pull-In, Lift-Off, Radio Frequency Micro Electro Mechanical Systems (RF MEMS)

A 9–12 GHz 5-bit active LO phase shifter with a new vector sum method

This paper presents a 5-bit active LO phase shifter with a new vector sum method for 9–12 GHz applications. The 5-bit phase shifter is composed of four 3-bit sub phase shifters by adopting the new vector sum method, which reduces the requirements on the resolution of the variable gain amplifier (VGA). The variable gain function is realized by switch on/off parallel input transistor pairs rather than changing the bias current of the VGA, which avoids the linearity variation and drain-source voltage variation existing in the quadrature vector sum active phase shifter. The 5-bit active LO phase shifter is fabricated in TSMC 0.13 μm CMOS technology. The measured results show that the phase shifter achieves 5-bit phase shift accuracy. The average conversion gain for 32 phase states is −0.5 to 7 dB from 9 to 12 GHz. The RMS gain error and the RMS phase error are smaller than 0.8 dB and 4° respectively. The current consumption is 27.7 mA from a 1.2 V supply voltage.

W-Band CMOS 4-Bit Phase Shifter for High Power and Phase Compression Points

A CMOS 4-bit phase shifter is designed for W-band applications using a 65-nm CMOS process. Switched-delay-type 90°, 45°, and 22.5° 1-bit phase shifters are designed to have high power-handling capability using a signal line bias voltage. The power and phase compression of 90°, 45°, and 22.5° phase shifters are analyzed, and the phase shifters are optimally cascaded for high power and phase compression points. The measured insertion loss of the 4-bit phase shifter is -25 ± 2.1 dB, and the root mean square (RMS) gain error of the 16 different phase states is 1.1 dB at 77 GHz. An input and output return loss is less than -8 dB at 70-85 GHz. The phase shifter has the RMS phase error of 7.20 at 77 GHz and is less than 11.25° at 75-85 GHz. The measured minimum 1-dB power compression point of 16 different phase states is 15.0 dBm. The high input power also compresses the phase adjustment range and increases the phase error, which is limited to 11.25° up to the input power of 21 dBm. The phase shifter consumes no dc current and occupies a small chip area of 0.122 mm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> , excluding pads.

Analysis of Magnetically Coupled All-Pass Network for Phase-Shifter Design

An all-pass network with magnetic coupling between its two inductors is analyzed in the context of phase-shifter design. Using even-odd mode analysis, the scattering parameters of the magnetically coupled all-pass network (MCAPN) are derived. Criteria for the network to provide an all-pass frequency response are obtained. Two switched-network phase-shifter topologies based on the MCAPNs are investigated. The results show that positive magnetic coupling between the inductors within the network boosts the amount of phase shift, whereas negative magnetic coupling broadens the bandwidth over which the phase shift remains constant. By using the MCAPNs for phase-shifter design, the tradeoff between the amount of phase shift and the bandwidth can be exploited, which not only adds to the design freedom, but suggests potential performance enhancement. For experimental verification, a 1-bit 22.5° phase shifter and a 4-bit 360° phase shifter are designed based on the analyzed MCAPNs with negative coupling factor. The measured phase error of the 1-bit phase shifter is less than 5% of the target phase shift from 2.38 to 4.80 GHz, corresponding to a bandwidth of 67%. The measured root mean square phase error of the 4-bit phase shifter is less than 3° from 1.62 to 3.89 GHz, which translates into a bandwidth of 82%.

SiGe process integrated full‐360° microelectromechanical systems‐based active phase shifter for W‐band automotive radar

This study presents the implementation of a microelectromechanical systems (MEMS)-based active phase shifter (APS) by using vector sum method. The proposed phase shifter comprises of two variable gain amplifiers (VGAs), a Wilkinson power divider with 90 phase shift lines, a Wilkinson power combiner and two 1-bit (0 degrees/180 degrees) MEMS phase shifters. First, all the components were designed and fabricated individually to check for their proper functionality, then they were brought together in a novel vector sum topology to work as a full-360 degrees span phase shifter. Fabricated VGAs function properly at designed frequency (77 GHz) with gain variation from 0 to 14 dB with the tuned base voltages from 1.8 to 2.3 V. The VGAs not only serve for providing the weighted amplitudes but also compensate 4.3 dB loss from 1-bit MEMS phase shifter and 0.8 dB loss from each power divider and combiner. Active/passive components and MEMS switches are all integrated at one single chip of 3.74 mm(2) and manufactured with IHP 0.25 mu m SiGe BiCMOS technology. As to the author's knowledge, this is the first demonstration of an APS using integrated active components and MEMS technology. Presented phase shifting mechanism can be used at automotive radar system for beam steering purpose.

A 4-bit CMOS phase shifter for millimeter-wave phased arrays

A 4-bit active phase shifter for millimeter-wave phased arrays is presented in this brief. The proposed phase shifter has achieved a phase-shifting range of $$360^{\circ }$$ 360 � with a $$22.5^{\circ }$$ 22 . 5 � resolution over 40 to 50-GHz. Thanks to the careful dimension designs of digitally controlled gain stage in the programmable weighted combiner, the active phase shifter achieves root-mean-square phase and gain errors of $$5^{\circ }$$ 5 � and 1.25-dB at 45-GHz, respectively. The measurement results also show that the input and output return losses are better than 7-dB from 40 to 50-GHz. The whole chip dissipates only 10.7-mA from 1.2-V supply excluding output driven buffer.

Design of digitally controlled multiple-pattern time-modulated antenna arrays with phase-only difference

An optimization approach based on differential evolution (DE) is proposed to design multiple-pattern time-modulated linear antenna arrays (TMLAAs) with phase-only control by using 5-bit digital phase shifters. The synthesized multiple patterns include a pencil beam (PB), a flat-topped beam (FTB), and a cosec squared pattern (CSP). The function of the DE is to find, simultaneously, a common, i.e., fixed, set of continuous values of switch-on time durations and discrete static excitation amplitudes for 5-bit digital attenuators, and different sets of discrete excitation phase distributions for 5-bit digital phase shifters; to generate different power patterns in the far field of the TMLAA. By perturbing the static amplitude distribution of a 20-element TMLAA in the discrete search range of “(0.2–1),” the patterns are obtained by reducing side lobe levels (SLLs) to almost −20 dB and sideband levels (SBLs) to less than −25 dB. Towards the end, the same on-time and amplitude distribution is used to produce a symmetric side lobe (S-SL) and asymmetric side lobe (A-SL) CSP, and their usefulness under a noisy signal environment is discussed.

Design of Phase Shift Control For Transmit/ Receive Module of ST Radar

The paper mainly focuses on the beam forming and its analysis for planar phased- array antenna, which is being developed as part of the ST Radar. The beam steering is done electronically by controlling the phase of the T/R module in such a way that the phase difference between each module is equal and it corresponds to the steering angle. The relative phase shift of each T/R module for a specified beam position is worked out using MATLAB and implemented using 6- bit digital phase shifter. The analytical results are practically demonstrated using the STM32F4xx kit of STMicroelectronics. Theoretical values of the elemental phase for each antenna element in the array, are calculated for various positions of the beam (θ &amp; φ). The 6-bit phase shifter results in 5.6250 phase resolution. In the second part of the work, the calculation of the element phase with 6-bit digital phase shifter is discussed. The calculated values of the elemental phase are truncated to an integral multiple of 5.6250.Â

Design and development of a CPW-based 5-bit switched-line phase shifter using inline metal contact MEMS series switches for 17.25 GHz transmit/receive module application

A radio frequency micro-electro-mechanical system (RF-MEMS) phase shifter based on switchable delay line concept with maximum desirable phase shift and good reliability is presented in this paper. The phase shifter is based on the switchable reference and delay line configurations with inline metal contact series switches that employs MEMS systems based on electrostatic actuation and implemented using coplanar waveguide (CPW) configuration. Electromechanical behaviour of the MEMS switch has been extensively investigated using commercially available simulation tools and validated using system level simulation. A detailed design and performance analysis of the phase shifter has been carried out as a function of various structural parameters with reference to the gold-based surface micromachining process on alumina substrate. The mechanical, electrical, transient, intermodulation distortion (IMD) and loss performance of an MEMS switch have been experimentally investigated. The individual primary phase-bits (11.25°/22.5°/45°/90°/180°) that are fundamental building blocks of a complete 5-bit phase shifter have been designed, fabricated and experimentally characterized. Furthermore, two different 5-bit switched-line phase shifters, that lead to 25% size reduction and result in marked improvement in the reliability of the complete 5-bit phase shifter with 30 V actuation voltage, have been developed. The performance comparison between two different CPW-based switched-line phase shifters have been extensively investigated and validated. The complete 5-bit phase shifter demonstrates an average insertion loss of 5.4 dB with a return loss of better than 14 dB at 17.25 GHz. The maximum phase error of 1.3° has been obtained at 17.25 GHz from these 5-bit phase shifters.