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In the trajectory of millimeter-wave (mmW) reconfigurable components advancement leveraging liquid crystals (LCs), a comprehensive array of planar and non-planar transmission lines, along with their diverse iterations, has emerged over the past two decades. This study introduces a unified framework for impedance characterization and benchmarking employing three distinct methodologies, i.e., Zpi (power-current), Zvi (voltage-current), and Zpv (power voltage). These frameworks are applied to three types of phase-variable transmission lines, namely, inverted microstrip line (IMSL), strip line (SL), and coaxial line (CL), each integrated with highly anisotropic nematic LCs as electronically tunable mediums. While these three topologies feature dual conductors, their fundamental disparity lies in the presence or absence of non-tunable dielectrics, thus influencing the interaction of mmW power with the transmission lines. Computational benchmarking at 60 GHz affirms the phenomenon of Zpi>Zvi>Zpv across the three topologies, albeit with varying degrees of deviation contingent upon geometric aspect ratios of the core line width to the LC layer thickness, as well as the permittivity ratio between tunable (LC) and non-tunable dielectrics (specifically pertinent to IMSL). Notably, aiming for 50 O at 60 GHz and with identical LC permittivity, the maximum deviation among the three impedances is 2.496 O for the IMSL, followed by 2.015 O for the strip line, and a minimal 0.254 O for the coaxial counterpart. Arguably, the deviations reduce with the enhancement of shielding towards a true TEM mode. Based on the impedance characterizations, a conservativeness assessment of TE11 cutoff guard band allowance for 300 GHz LC-filled coaxial phase shifters is conducted. Extending the implications of these findings, such a nuanced understanding of impedance characteristics and deviation patterns is instrumental in optimizing the design and performance of mmW reconfigurable components utilizing LC-based transmission lines towards enhanced adaptability and performance in diverse applications such as 5G/6G wireless communication networks, radar systems, and beyond. [ABSTRACT FROM AUTHOR]

In this paper, we present a high power-added efficiency (PAE) and high gain per stage 60 GHz power amplifier (PA). The proposed PA consists of a two-stage common-source amplifier that incorporates neutralization capacitors and compensation inductors to enhance both gain and efficiency. The gain characteristics are analyzed, demonstrating that the proposed design improves both gain and efficiency. Implemented in 65 nm CMOS technology, the PA achieves a saturated output power of 13.4 dBm at 60 GHz, with a maximum PAE of 26.7% from a 1 V supply. The output 1 dB compression point is 10.5 dBm, with a PAE of 16%. The PA occupies a core chip area of 0.094 mm2. [ABSTRACT FROM AUTHOR]

This work demystifies the role that packaging boundary conditions (both physically and electromagnetically) can play in a nematic liquid crystal (NLC)-based inverted microstrip (IMS) phase shifter device operating at the 60 GHz band (from 54 GHz to 66 GHz). Most notably, the air box radiating boundary and perfect electric conductor (PEC) enclosing boundary are numerically examined and compared statistically for convergence, scattering parameters, and phase-shift-to-insertion-loss ratio, i.e., figure-of-merit (FoM). Notably, the simulated phase tunability of the radiating air box boundary structure is 8.26°/cm higher than that of the encased (enclosed) PEC boundary structure at 60 GHz. However, the maximum insertion loss of the encased PEC structure is 0.47 dB smaller compared to that of the radiant air box boundary structure. This results in an FoM increase of 29.26°/dB at the enclosed PEC limit (relative to the less-than-optimal airbox radiation limit). Arguably, the NLC-filled IMS phase shifter device packaging with metals fully enclosed (in addition to the default ground plane) enhances the symmetry of the structure, both in the geometry and the materials system. In electromagnetic parlance, it contributes to a more homogenously distributed electric field and a more stable monomodal transmission environment with mitigated radiation and noise. Practically, the addition of the enclosure to the well-established NLC-IMS planar fabrication techniques provides a feasible manufacturing (assembling) solution to acquire the reasonably comparable performance advantage exhibited by non-planar structures, e.g., a fully enclosed strip line and rectangular coaxial line, which are technically demanding to manufacture with NLC. [ABSTRACT FROM AUTHOR]

This paper presents the implementation of a low-power and variable-gain 60 GHz millimeter-wave CMOS Amplifier designed for short-range multi-gigabit close proximity point-to-point communications. The design uses coplanar wave transmission lines to achieve 50 Ω input and output matching. Realized in a 90 nm CMOS process, the variable-gain VGA exhibits power consumption ranging from 4.7 mW to 39.1 mW, with gains spanning from 5.5 dB to 12.4 dB at 60 GHz and a 3 dB bandwidth exceeding 14.4 GHz. Input and output return losses remain below –10 dB across the gain spectrum. Successful demonstration of gain controllability further validates the circuit's performance. The compact VGA die, inclusive of pads, has dimensions of 740 μm by 920 μm, thereby occupying a core area of 0.2 mm2. This design demonstrates the potential of low-power, high-performance VGAs in enhancing millimeter-wave communication systems. [ABSTRACT FROM AUTHOR]

In this paper, a wideband, high-gain microstrip patch antenna design for 60 GHz applications is presented. The chosen substrate material is Rogers RT 5880, with a thickness of 1.6 mm, a relative permittivity of 2.2, and a loss tangent of 0.0009. Initially, a simple rectangular patch antenna is designed. To address the challenges of low gain and low radiation efficiency, two rectangular parasitic elements are introduced. These parasitic elements interact with the main radiator, resulting in improved gain and radiation efficiency. In the final step, an extended ground plane structure is adopted to further enhance return loss, radiation efficiency, and gain. The proposed antenna achieves a high gain of 13.10 dBi and a maximum radiation efficiency of 90% with a compact size of 13.6 × 10.6 mm2. For bandwidth calculations, given that the 60 GHz frequency band is known for its challenging propagation environment, the -15 dB criteria is chosen instead of the commonly used -10 dB criterion. According to this -15 dB criterion, the antenna exhibits wideband behavior spanning from 55 to 65 GHz, offering animpressive impedance bandwidth of 10 GHz. This design demonstrates significant potential for 60 GHz applications.

This paper investigates a 60 GHz low-power broadband low noise amplifier (LNA) with variable gain control. To prove the concept, the circuit is implemented in a 22nm fully depleted silicon on insulator (FD-SOI) CMOS technology. It supports broadband operation at 60 GHz achieved by gain peaking (gain distribution) technique. By tuning some key matching networks of the amplifier, the peak gain of each stage was distributed to different frequencies resulting in an overall broadband frequency response. The circuit consists of three cascaded cascode amplifier stages. Matching networks were optimized regarding bandwidth and noise figure. The transistor back-gate was used for LNA designs to switch the circuit to low-power standby mode. This avoids the problems of front-gate based switching regarding voltage breakdown and circuit stability. Additionally, simultaneous realization of variable gain control at such high frequencies was achieved via the back-gate. Compared to the front-gate based, the back-gate based variable gain control can deliver a continuous fine-tuning of the gain while requiring less accuracy or resolution of the control voltage. In the measurement, The gain was successfully tuned from 20dB down to -25dB via the back-gate. At a DC power of 8.1mW from a nominal supply of 1V, the LNA provides a peak gain of 20dB, a bandwidth of 18.5 GHz, and a minimum noise figure of 3.3dB. When biased at a reduced DC supply of 0.4V, the presented circuit consumes only 2.5mW of DC power, and still provides a power gain of 10dB and a minimum noise figure of around 4.5dB. By switching to standby mode, the LNA consumes 850 $\mathrm {\mu W }$ of DC power at the nominal supply and 240 $\mathrm {\mu W }$ at the reduced supply. The LNA compares well against previously reported designs by showing the lowest noise figure with competitive gain, bandwidth and DC power. To the authors’ knowledge, this is the first 60 GHz LNA featuring joined variable gain control and switching capability via solely back-gate biasing.

This work serves as the first simulation investigation to tackle the liquid crystal (LC)-filled coaxially structured continuously variable phase shifter at 60 GHz, wherein the LCs act as single tunable dielectrics fully occupying the millimeter-wave (mmW) power transmitted (i.e., free of leakage or interference). Impedance and effective dielectric constant computations are settled, followed by the quantification of the interplay between the dielectric thickness and the dielectric constant (Dk) for a controlled 50 Ω impedance. Geometry's aspect ratio (AR) effects are exploited for the coaxially accommodating topology filled with mmW-tailored LCs with an operatable Dk range of 2.754 (isotropic state) to 3.3 (saturated bias state). In addition to the proposed structure's noise-free advantages, a novel figure of merit (FoM) enhancement method based on Dk-selection-based impedance matching is proposed. The optimum FoM design by simulation exhibits a 0–180.19° continuously variable phase shift with a maximum insertion loss of 1.75871 dB, i.e., a simulated FoM of 102.46°/dB when the LC-filled coaxial geometry is 50 Ω and matched with the Dk of 2.8, corresponding to the dielectric thickness of 0.34876 mm and line length of 15.92 mm. The envisioned device fabrication and assembly processes are free of the conventional polyimide alignment agent and the related thermal and electrical concerns. Significant cost reduction and yield improvement can hence be envisaged. The topology can also serve as a test structure for broadband characterizations of LC materials and new electro-optical effects. [ABSTRACT FROM AUTHOR]

Integrated access and backhaul (IAB) networks offer transformative benefits, primarily their deployment flexibility in locations where fixed backhaul faces logistical or financial challenges. This flexibility is further enhanced by IAB's inherent ability for adaptive network expansion. However, existing IAB network planning models, which are grounded in the facility location problem and are predominantly addressed through linear programming, tend to neglect crucial geographical constraints. These constraints arise from the specific deployment constraints related to the positioning of IAB donors to the core network, and the geographic specificity required for IAB-node placements. These aspects expose an evident research void. To bridge this, our research introduces a geographically aware optimization methodology tailored for IAB deployments. In this paper, we detail strategies for both single-hop and multi-hop situations, concentrating on IAB donors distribution and geographical constraints. Uniquely in this study, we employ the inherent data rate limitations of network nodes to determine the maximum feasible hops, differing from traditional fixed maximum hop count methods. We devise two optimization schemes for single-hop and multi-hop settings and introduce a greedy algorithm to effectively address the non-convex multi-hop challenge. Extensive simulations across various conditions (such as diverse donor numbers and node separations) were undertaken, with the outcomes assessed against the benchmark of the single-hop scenario's optimal solution. Our findings reveal that the introduced algorithm delivers efficient performance for geographically constrained network planning. [ABSTRACT FROM AUTHOR]

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In this study, we propose a compact, tri-band microstrip patch antenna for 5G applications, operating at 28 GHz, 38 GHz, and 60 GHz frequency bands. Starting with a basic rectangular microstrip patch, modifications were made to achieve resonance in the target frequency bands and improve S11 performance, gain, and impedance bandwidth. An inset feed was employed to enhance antenna matching, and a π–shaped slot was incorporated into the radiating patch for better antenna characteristics. The design utilized a Rogers RT/Duroid-5880 substrate with a 0.508 mm thickness, a 2.2 dielectric constant, and a 0.0009 loss tangent. The final dimensions of the antenna are 8 x 8.5 x 0.508 mm³. The maximum S11 values obtained at the resonant frequencies of 27.9 GHz, 38.4 GHz, and 56 GHz are -15.4 dB, -18 dB, and -26.4 dB, respectively. The impedance bandwidths around these frequencies were 1.26 GHz (27.245 - 28.505), 1.08 GHz (37.775 - 38.855), and 12.015 GHz (51.725 - 63.74), respectively. The antenna gains at the resonant frequencies are 7.96 dBi, 6.82 dBi, and 7.93 dBi, respectively. Radiation efficiencies of 88%, 84%, and 90% were achieved at the resonant frequencies. However, it is observed that the radiation is maximum in the broadside direction at 28 GHz, although it peaks at −41°/41° and −30°/30° at 38 GHz and 56 GHz, respectively. Furthermore, the antenna design, simulations, and optimizations were carried out using HFSS, and the results were verified with CST. Both simulators showed a reasonable degree of consistency, confirming the effectiveness and reliability of the proposed antenna design. [ABSTRACT FROM AUTHOR]

Millimeter wave bands (30–300 GHz) are attracting a lot of research attention because they can possibly lead to data rates of nearly 10 Gbits/s, a lot of accessible bandwidth, narrow beam, good transmission quality, and excellent detection abilities compared to microwave frequencies which are restricted to 1 Gbits/s. This paper presents a comprehensive survey of the recent research developments on antenna designing specifically at 30, 60 and 120 GHz mmWave wireless communication bands along with their characteristics, applications, limitations, material selection, challenges, and proposed solutions. Several mmWave antennas published in the literature are covered in this study, including their type, characteristics, design challenges, and future research prospects. A comparison of various mmWave antennas published recently are analysed in terms of gain, bandwidth, efficiency, number of elements and type of antenna technology. At last, the design techniques such as Antenna-in-Package (AiP), Antenna-on-Chip (AoP) and various fabrication technologies are described including their merits as well as demerits. [ABSTRACT FROM AUTHOR]

This study proposes a 3GPP-compatible channel generation framework for ultra-wideband and indoor short-range communication realized by the fifth-generation (5G) new radio operating in the frequency range (FR) of 52.6–71.0 GHz. The addition of this band, coined “FR2–2,” to the 5G specification allows foreseeing the use cases of shorter-range communications with ultra-wide bandwidth. However, the current focus of the 3GPP channel model on longer-range communication hinders link-level simulations of this use case. To fill this void, we develop a channel generation framework compatible with the 3GPP channel model and applicable to the FR2-2 indoor short-range use case based on real channel measurements. We highlight that even with appropriate parameters for this use case, the 3GPP channel model does not necessarily reproduce similar characteristics of the measured channel impulse response (CIR) owing to the lack of uniformity of cluster angle of arrival (AoA) and power dispersion in intra-cluster subpaths. Based on this finding, an amendment is proposed, where cluster AoA is uniformly distributed, and the intra-cluster power dispersion term is introduced. We demonstrate the feasibility of the proposed framework for reproducing the real CIR characteristic by showcasing an agreement of root-mean-square delay and angular spreads with the measured CIR.

If a wireless channel is said wide-sense stationary (WSS), the mean and autocorrelation of its small-scale fading are position invariant. This occurs when the channel is rich in propagation paths – their complex summation averages out any position-specific characteristics. Extensive measurement campaigns have validated the microwave channel to be WSS – it is inherently rich in diffracted paths, the 1G to 4G systems that operate there employ omnidirectional antennas which detect paths from all directions, and the systems feature narrow bandwidths which sum paths over long sample periods. Popular millimeter-wave (mmWave) channel models assume the channel is WSS without measurement-based validation even though the channel is inherently sparse due to weak diffraction, and the 5G systems that operate there employ pencilbeam antennas and feature ultrawide bandwidths. In fact, a recent measurement campaign showed the 60 GHz channel is non-WSS at narrow beamwidths and wide bandwidths, however the campaign considered only one measured channel and only a discrete set of beamwidths and bandwidths. For comprehensive analysis, in this paper we measured 88 channels over three indoor and two outdoor environments with our 60 GHz channel sounder and varied the beamwidth and bandwidth continuously to find the crossover points when the channel transitions from WSS to non-WSS.

This paper presents a 52-to-57 GHz CMOS quadrature voltage-controlled oscillator (QVCO) with a novel I/Q phase tuning technique based on a body bias control method. The QVCO employs an in-phase injection-coupling (IPIC) network comprising four diode-connected FETs for the quadrature phase generation. The I/Q phase error is calibrated by controlling the body bias voltage offset of the QVCO's four core FETs. This technique effectively covers a wide range of I/Q phase error between −13.4° and +10.7°. It also minimally induces the unwanted variations in the phase noise, current dissipation, and oscillation frequency, which were found to be only 0.4 dB, 0.07%, and 36 MHz, respectively. After the IPIC-QVCO, a phase-tunable two-stage LO buffer employing a 3-bit switched-capacitor bank was added for additional phase tuning, leading to the extension of the phase tuning range up to −22.7–+20.0°. The proposed QVCO is implemented in a 40 nm RF CMOS process. The measured results show that the QVCO covers a frequency band from 52.4 to 57.6 GHz while consuming 26.2 mW. The phase noise and the figure-of-merit of the QVCO are −91.8 dBc/Hz at 1 MHz offset and −172.4 dBc/Hz, respectively. We also realized a fully integrated 55 GHz quadrature RF transmitter employing the phase-tunable QVCO and LO generator. The effectiveness of the proposed phase-tunable LO generator was confirmed by verifying the image rejection ratio (IRR) calibration at the RF output. [ABSTRACT FROM AUTHOR]

Fixed wireless access (FWA) provides a solution to compete with fiber deployment while offering reduced costs by using the mmWave bands, including the unlicensed 60 GHz one. This paper evaluates the deployment of FWA networks in the 60 GHz band in realistic urban and rural environment in Belgium. We developed a network planning tool that includes novel backhaul based on the IEEE 802.11ay standard with multi-objective capabilities to maximise the user coverage, providing at least 1 Gbps of bit rate while minimising the required network infrastructure. We evaluate diverse serving node locations, called edge nodes (EN), and the impact of environmental factors such as rain and vegetation on the network design. Extensive simulation results show that defining a proper EN's location is essential to achieve viable user coverage higher than 95%, particularly in urban scenarios where street canyons affect propagation. Rural scenarios require nearly 75 ENs per km 2 while urban scenarios require four times (300 ENs per km 2 ) this infrastructure. Finally, vegetation can reduce the coverage by 3% or increment infrastructure up to 7%, while heavy rain can reduce coverage by 5% or increment infrastructure by 15%, depending on the node deployment strategy implemented. [ABSTRACT FROM AUTHOR]

A 60 GHz power amplifier (PA) monolithic microwave integrated circuit (MMIC) with +28 dBm output power is designed in an enhancement-mode 0.15 μm GaAs pseudomorphic high-electron-mobility transistor (pHEMT) technology. A two-stage topology and a four-way power combining technique are adopted to achieve a high power gain, high output power, and high linearity. Transistor-level circuit and layout designs are developed, and the circuit performances are verified through three-dimensional electromagnetic simulations. The designed PA MMIC exhibits a saturated output power of +28.4 dBm, output-referred 1-dB gain compression point of +28 dBm, power gain of +8.1 dB, and power added efficiency of 29.3 %. S-parameter simulations show that the small-signal gain is +8.1 dB, and the operating bandwidth is between 55.7 and 63.1 GHz, with a fractional bandwidth of 12.3 %. The supply voltages are 4 V for the drain and 0.6 V for the gate. The positive-only supply voltages resulting from the enhancement-mode pHEMT simplify the supply voltage network compared with the conventional depletion-mode pHEMT design. The layout die size of the PA MMIC is 1.99×1.62 mm², and the power density performance of 214 mW/mm² is satisfactory. [ABSTRACT FROM AUTHOR]

Wireless connectivity has been realized for multiple environments and different frequency bands. However, little research exists about mmWave communication in industrial environments. This paper presents the 60 GHz double-directional radio channel for mmWave communication in a ship hull for Line-of-Sight (LOS) and non-Line-of-Sight (NLOS) conditions. We performed channel measurements using the Terragraph channel sounder at different locations in the ship hull and fitted LOS path loss to a one-slope path loss model. Path loss and root-mean-square delay spread of the LOS path is compared to the reflected path with lowest path loss. NLOS communication via this first-order reflected path is modeled by calculating the path distance and determining the reflection loss. The reflection losses have a considerable contribution to the signal attenuation of the reflected path. The channel models are implemented in an indoor coverage prediction tool, which was extended with a ray launching algorithm and validated by comparison with an analytical electromagnetic solver. The results show that the mmWave radio channel allows high-throughput communication within a ship hull compartment, even when no LOS path between the transmitter and receiver is present. [ABSTRACT FROM AUTHOR]

This letter proposes a 60 GHz planar waveguide array antenna with high antenna efficiency, low cost, and low processing difficulty. The array integrates the radiating elements and the hollow E-plane waveguide feed network in a single-layer structure in a simple way. To demonstrate the idea, a 16×16 prototype was designed, fabricated, and measured. The measured 10 dB impedance bandwidth (|S11| ≤ −10 dB) is 16.4% with the antenna efficiency being 89.1% at 61.5 GHz. To the best of our knowledge, it has the highest antenna efficiency and the lowest processing difficulty among similar waveguide arrays. [ABSTRACT FROM AUTHOR]

Abstract The aim of this work is to study the impact of small receiver displacement on a signal propagation in a typical conference room environment at a millimeter wave frequency of 60 GHz. While channel measurements provide insights on the propagation phenomena, their use for the wireless system performance evaluation is challenging. Whereas, carefully executed three-dimensional ray tracing (RT) simulations represent a more flexible option. Nevertheless, a careful validation of simulation methodology is needed. The first target of this article is to highlight the benefits of an in-house built three-dimensional RT tool at 60 GHz and shows the effectiveness of simulations in predicting different characteristics of the channel. To validate the simulation results against the measurements, two different transmitter (Tx) positions and antenna types along with ten receiver (Rx) positions are considered in a typical conference room. In first system configuration, an omnidirectional antenna is placed in the middle of the table, while in the second system configuration a directed horn antenna is located in the corner of the meeting room. After validating the simulation results with the measurement data, in the second part of this work, the impact of a small change, i.e., 20 cm in the receiver position, is studied. To characterize the impact, we apply as performance indicators the received power level, root mean square delay spread (RMS-DS) and RMS angular spread (RMS-AS) in azimuth plane. The channel characteristics are considered with respect to the direct orientation (DO), i.e., the Rx antenna is directed toward the strongest incoming path. Different antenna configurations at the Tx and Rx side are applied to highlight the role of antenna properties on the considered channel characteristics. Especially, in the second system configuration the impact of different antenna half power beamwidth on different considered channel characteristics is highlighted through acquired simulation results. The validation of results shows the RMS error of only 2–3 dB between the measured and simulated received power levels for different Tx configurations in the direction of DO. Results indicate that only a small change of the Rx position may result a large difference in the received power level even in the presence of line-of-sight between the Tx and Rx. It is found that the STD of received power level across the room increases with the decrease in HPBW of the antenna. As can be expected, directed antennas offer lower value of RMS-DS and RMS-AS compared with isotropic antenna.

Traditional wired interconnects in multicore multichip (MCMC) systems can be replaced with chip-integrated switched beam antenna arrays to provide reconfigurable chip-to-chip communications. By simply switching the directive beams of the arrays, the chips can be made to dynamically communicate with their surrounding neighbors. Radiation from the arrays in the unintended direction, however, causes interference when multiple pairs of chips are simultaneously communicating. In this paper, the noise and interference limitations of such concurrent chip-to-chip communication systems are analyzed at 60 GHz for the channels defined in the IEEE 802.11ay standard. Each array consists of eight substrate integrated waveguide (SIW) horn elements printed on a thin dielectric substrate. The elements can be individually excited to produce eight directive endfire beams, providing full 360° coverage, in the horizontal plane. The substrate acts as a hybrid space-surface wave interconnect (HSSW-I) that allows near-field, space and surface wave coupling to occur between the arrays, and thus, increases interchip transmission. The antenna and link parameters that dictate the signal-to-noise-plus-interference ratio (SNIR) of such systems are established by considering all the major components. The maximum achievable data rates are then determined based on the SNIR, calculated from the measured and simulated transmission coefficients between the arrays.

This paper presents a 60 GHz millimeter-wave (mm-wave) antenna array using standard printed circuit board (PCB) for 3D Antenna-in-package (AiP) implementation. The array consists of a 4 microstrip patch elements, differentially fed with an open stub matching feed network to enable 3D integration. The $1\times 4$ finite antenna array with ball grid array (BGA) and silicon (Si) interposer operates from 58.46 to 62.14 GHz with 3.6 GHz instantaneous bandwidth, low mutual coupling of about $1\times 4$ array consists of two substrates and one bondply layer with antennas, via-to-open stub matching network, and a differential to single-ended corporate feed network for the measurement. A prototype with a differential to single-ended corporate feed network was fabricated and tested showing a gain of about 10.02 dBi at the operating frequency with $\geq 90$ % radiation efficiency. Such a gain and efficiency make the presented design a leading candidate for 3D AiP applications.

This paper presents a 60 GHz CMOS I/Q receiver for the high-speed wireless communication system. It consists of a low noise amplifier, single-to-differential (S2D) amplifier, passive mixer, buffer amplifier with passive I/Q generator, and wideband baseband amplifier (BBA) stage. The measured conversion gain of 51 dB is achieved. The baseband bandwidth of 300 MHz is achieved from 57 GHz to 60 GHz. The 90° tandem coupler was implemented for I/Q signal generation, which has a phase error of <7° and an amplitude imbalance of <2 dB from 55 to 62 GHz. The Marchand balun is used to convert the I/Q signal to the differential, which has a phase error of <4°. A 60 GHz CMOS I/Q receiver is designed and fabricated, using a commercial 40 nm CMOS bulk process. The size of the receiver is 2.02 × 1.45 mm2, including the pads. The circuit is operated from a 0.9 V supply. The power consumption is 172 mW at maximum gain mode. [ABSTRACT FROM AUTHOR]

This letter presents an ultra-compact two-stage 60-GHz differential bi-directional amplifier (DBA) design in a 65-nm CMOS process. To satisfy the stability and gain requirements, a differential neutralized bi-directional common-source gain cell combined with the cross-coupled gm-boosting technique is proposed. In addition, a layout-symmetrical coupled line transformer is used as the inter-stage matching network to achieve broadband operation, reducing insertion loss and ensuring identical responses in both forward/backward modes. The proposed DBA achieves a peak gain of 16.1 dB with a 3-dB bandwidth of 15 GHz (52–67 GHz), maximum OP $_{\mathrm {1 \,\,dB}}$ of 5.1 dBm, $P_{\mathrm {SAT}}$ of 9.6 dBm, a peak PAE of 11.5% at 62 GHz, respectively, consuming 70 mW from a power supply of 1.2 V. The circuit core occupies an ultra-compact area of only 0.0675 mm2. [ABSTRACT FROM AUTHOR]

This paper presents a method for phase noise impact compensation in 60 GHz OFDM receivers and provides the results of performance evaluation using OFDM PHY parameters defined in the IEEE 802.11ay standard. It is shown that the phase noise in 60 GHz band has a critical impact on the OFDM performance for high data rate transmission employing high order modulation constellations. The proposed compensation method combines time domain algorithm predicting the linear average phase trend on the OFDM symbol duration and estimation in frequency domain of phase noise spectrum realization and convolution with correction filter response. Both algorithms use Maximum A Posteriori Probability (MAP) estimation approach to find the optimal solution and are applied successively. The proposed algorithms have moderate implementation complexity which is especially important for high speed 11ay hardware modem architecture. The performance of the proposed algorithms is evaluated in the frequency flat and frequency selective channels with phase noise model adopted in the IEEE 802.11ay.

The millimeter-waves band will enable multi-gigabit data transmission due to the large available bandwidth and it is a promising solution for the spectrum scarcity below 6 GHz in future generations of mobile networks. In particular, the 60 GHz band will play a crucial role in providing high-capacity data links for indoor applications. In this context, this tutorial presents a comprehensive review of indoor propagation models operating in the 60 GHz band, considering the main scenarios of interest. Propagation mechanisms such as reflection, diffraction, scattering, blockage, and material penetration, as well as large-scale path loss, are discussed in order to obtain a channel model for 60 GHz signals in indoor environments. Finally, comparisons were made using data obtained from a measurement campaign available in the literature in order to emphasize the importance of developing accurate channel models for future wireless communication systems operating in millimeter-waves bands.

This paper presents a 60 GHz connected slots linear-phased array feeding a high-gain semi-symmetric lens antenna. This design provides high gain, broadband, and beam-steering capabilities for gigabit rate access and backhaul communications. The connected slots antenna array (CSAA) is excited at 16× equidistant points which not only yields spatial power combining but also allows the progressive phase changes to steer the beam in ±45° in azimuth plane. To characterize the CSAA-fed lens antenna, four different power splitters are fabricated which steer the main beam in 0, 15, 30, and 45°. The lens is designed in a way to overcome the scan loss and get comparatively higher gain when beam is steered away from the broadside. The measured results show 25.4 dBi maximum gain with 3 dB gain bandwidth covering the full band 57–66 GHz whereas 3 dB beam-steering range is ±45° for all frequencies. Besides, the half power beamwidth is 6 and 10° in elevation (E-plane) and azimuth plane (H-plane), respectively. [ABSTRACT FROM AUTHOR]

This article presents a 60 GHz coplanar fed slotted antenna based on substrate integrated waveguide (SIW) technology for beam-tilting applications. The longitudinal passive slots are fed via associated SIW holes adjacent to the coplanar feed while the main excitation is provided from the microstrip-to-SIW transition. The antenna array achieves an impedance bandwidth of 57–64 GHz with gains reaching to 12 dBi. The passive SIW slots are excited with various orientations of coplanar feeds and associated holes covering an angular beam-tilting from −56° to +56° with an offset of 10° at the central frequency. The novelty of this work is; beam-tilting is achieved without the use of any active/passive phase shifters which improves the design in terms of losses and provide a much simpler alternative compared to the complex geometries available in the literature at the 60 GHz band. [ABSTRACT FROM AUTHOR]

This brief presents a 54–68 GHz two-stage power amplifier (PA) with linearity and efficiency enhancement in a 40 nm CMOS process. The first stage adopts a current reuse cascaded common-source (CS) structure with a shunt RC feedback to maximize the gain and minimize the DC power consumption to boost the linearity and efficiency, while the second stage is a cascode structure with two built-in linearizers to enhance the linearity much further. Based on the proposed structure, the fabricated PA exhibits measured output of 1-dB compression point, saturated output power, power added efficiency (PAE) and AM-PM distortion of +14 dBm, +15 dBm, 20% and 8 degrees, respectively. In addition, the proposed CMOS PA achieves high and flat power gain of 14 dB with ripple less than 1.5 dB through the operating 54—68 GHz frequency band while consuming only 110 mW. [ABSTRACT FROM AUTHOR]

This article presents a 71–86 GHz 16-element array receiver application-specified integrated circuit (ASIC) for Massive multiple-input–multiple-output (MIMO) wireless uplink, featuring a multiple-output analog beamformer (BF) supporting up to 16 spatially multiplexed users at the same time. The ASIC includes 16 direct-conversion mixer-first RX front-ends, local oscillator (LO) generation and distribution, and a $16\times 16$ fully connected baseband analog beamformer, which derives each user stream as a linear combination of all the 16 antennas. The 16 mm2 28 nm CMOS ASIC is packaged on an organic interposer including a linear patch antenna array. Over-the-air measurements demonstrate up to 2 Gb/s single-user data-rate, and four simultaneous links at 500 Mb/s each, with number of users and data rate only limited by setup constraints. Circuits are optimized for low power consumption in order to enable scaling to massive arrays, and consumes 1.7 W total power, for a power figure of 7 mW/antenna/user. [ABSTRACT FROM AUTHOR]

This work presents a ${12}\,\,\times \,\,{12}\,\,\times \,\,{0.6}$ mm3 ball grid array (BGA) module made of low-cost organic substrates which integrates transmitter (Tx) and receiver (Rx) antennas for short-range 60 GHz WiGig communications. The Tx antenna is a single-element linearly polarized aperture-coupled patch (ACP) antenna achieving a worst −12 dB matching with a broadside realized gain above 5 dBi and a total efficiency higher than 50% in the 57–66 GHz band. The Rx antenna is a single-element single-fed circularly polarized ACP antenna. It exhibits a worst −14 dB matching level from ${57~}$ to 66 GHz and a worst −10 dB level from ${47~}$ to 66 GHz (33% relative bandwidth (BW) with respect to 60 GHz). The broadside realized gain is above 5 dBi from ${61~}$ to 67 GHz and the axial ratio stays below 3 dB for a 14% BW with respect to 60 GHz. Variability of the fabrication process is analyzed by means of extensive measurements of several modules. The effect of the integration of the module in the application PCB and the device casing is also studied for realistic use. The obtained results demonstrate suitability of this high-density interconnect BGA packaging technology for mass production of compact low-cost millimeter-wave (mmW) antenna module for WiGig communications. [ABSTRACT FROM AUTHOR]

A low cost, broadband and compact antenna in package solution (AiP) is proposed for 60 GHz low-power radar sensor applications. Following a glass integrated passive device (Glass-IPD) manufacturing process, a compact low cost taper slot antenna (TSA) is designed on a substrate with a thickness beyond Yngvesson's range. To realize high gain and front-to-back ratio, the antenna is optimized by introducing a truncated ground. A 1 × 2 antenna array prototype is realized with a dummy transmission line chip in the dimension of 5 × 7.4 mm2. Including the flip chip interconnect, the measured results demonstrate a 10 dB impedance bandwidth of 47.2 ~ 67 GHz. The calculated gain is higher than 6.5 dBi in the end-fire direction over the entire 60 GHz band. Based on a physical RLC equivalent circuit, by co-design of the antenna with solder balls, the flip chip interconnect is compensated with a passive network. For the compensation network, its working bandwidth is from 0.1 to 67 GHz, while its insertion loss at 60 GHz is less than 0.2 dB.

This letter presents the first duty-cycled low-noise amplifier (LNA) operating in the V-band (40–75 GHz). The amplifier employs a two-stage cascode topology and focuses on low power consumption and therefore fast settling times. The switching is achieved by using inverters at the common-gate (CG) transistor of the cascode stage. This control technique enables adapting the duty-cycle and, therefore, the data rate depending on the required performance. The LNA can be operated in an oversampling mode fulfilling a wake-up function and consuming only 22 μW for a data rate of 294 kb/s or in continuous mode dissipating 3.6 mW. A settling time of 0.6 ns, a rise time of 19 ps, and a fall time of 27 ps have been experimentally demonstrated on a prototype fabricated in a 22 nm fully-depleted silicon-on-insulator (FD-SOI) technology. The measurement results include a peak gain of 18 dB, a 3-dB bandwidth of 18 GHz, an average noise figure (NF) of 4.9 dB within the 3-dB band, and an input 1 dB compression point (P1dB) at 60 GHz of −21.1 dBm. [ABSTRACT FROM AUTHOR]

A 60 GHz fully-integrated 8-way combined power amplifier (PA) is developed in a standard 0.18 μm SiGe BiCMOS technology. The 8-way power splitter and combiner are co-optimized with transformer based baluns inside the eight differential PA cells, and hence resulting in minimum loss and high gain, linearity and efficiency. The measurement shows that the PA can achieve a gain of 22.2 dB around 60 GHz and 3-dB bandwidth from 53.5 GHz to 66.5 GHz, which covers all the channels specified in IEEE 802.11ad standard. It also attains a 1-dB power compression point (P1dB) of 21.8 dBm and saturated output power (PSAT) of 22.6 dBm, with power-added-efficiency of 10.7% and 12%, respectively. [ABSTRACT FROM AUTHOR]

This letter proposes a novel antenna structure for 60  GHz band 3-D coverage beamforming. By using the proposed antenna structure, the coverage area can be expanded in an elevation plane. Dipole and patch subarray antennas were packaged into one structure by using the copper balls interconnection technique. A simple idea to utilize dipole and patch elements enables endfire and broadside radiations resulting in the coverage area expansion in the elevation plane. Two 2 × 4 array antennas were made up of eight multilayered substrate. Six metal layers were used for each multilayered substrate. [ABSTRACT FROM AUTHOR]

This paper presents another alternative design of monopole microstrip patch antenna for millimeter wave (MMW) short range wireless communications applications. The purpose of this paper is to discuss a new design of antenna that operates in the MMW frequency range at 60 GHz. The design is based on single element with full size of 9 x 11 mm² that contains two elliptical loops monopole antenna and a line feed of 50 ohm on the top layer of substate with a partial ground plane on the opposite side. Microstrip-patch antenna has been designed and implemented for 5G wireless communication technology at 60 GHz with low-cost and small size substrate that makes it suitable for small devices. In the proposed design, the used substrate material is Roger RT6035htc lossy with relative dielectric 3.5 and loss tangent 0.0013 with partial ground plane to improve the impedance characteristics. The designed antenna provides a uniform current distribution over the surface of antenna at the resonance frequency with an acceptable realized gain of 4.8 dBi in the far-zone with a return loss reaches up to – 33 dB. The simulation results are carried out using high frequency structure simulator (HFSS), FEM is based on full 3D wave electromagnetic solver simulator from Analysis and the obtained results confirm the suitability of the proposed MMW antenna to be a good candidate for 5G applications. [ABSTRACT FROM AUTHOR]

The aim of this work is to study the impact of small receiver displacement on a signal propagation in a typical conference room environment at a millimeter wave frequency of 60 GHz. While channel measurements provide insights on the propagation phenomena, their use for the wireless system performance evaluation is challenging. Whereas, carefully executed three-dimensional ray tracing (RT) simulations represent a more flexible option. Nevertheless, a careful validation of simulation methodology is needed. The first target of this article is to highlight the benefits of an in-house built three-dimensional RT tool at 60 GHz and shows the effectiveness of simulations in predicting different characteristics of the channel. To validate the simulation results against the measurements, two different transmitter (Tx) positions and antenna types along with ten receiver (Rx) positions are considered in a typical conference room. In first system configuration, an omnidirectional antenna is placed in the middle of the table, while in the second system configuration a directed horn antenna is located in the corner of the meeting room. After validating the simulation results with the measurement data, in the second part of this work, the impact of a small change, i.e., 20 cm in the receiver position, is studied. To characterize the impact, we apply as performance indicators the received power level, root mean square delay spread (RMS-DS) and RMS angular spread (RMS-AS) in azimuth plane. The channel characteristics are considered with respect to the direct orientation (DO), i.e., the Rx antenna is directed toward the strongest incoming path. Different antenna configurations at the Tx and Rx side are applied to highlight the role of antenna properties on the considered channel characteristics. Especially, in the second system configuration the impact of different antenna half power beamwidth on different considered channel characteristics is highlighted through acquired simulation results. The validation of results shows the RMS error of only 2–3 dB between the measured and simulated received power levels for different Tx configurations in the direction of DO. Results indicate that only a small change of the Rx position may result a large difference in the received power level even in the presence of line-of-sight between the Tx and Rx. It is found that the STD of received power level across the room increases with the decrease in HPBW of the antenna. As can be expected, directed antennas offer lower value of RMS-DS and RMS-AS compared with isotropic antenna. [ABSTRACT FROM AUTHOR]

In this paper performance of three different designs of a 60 GHz high gain antenna for body-centric communication has been evaluated. The basic structure of the antenna is a slotted patch consisting of a rectangular ring radiator with passive radiators inside. The variation of the design was done by changing the shape of these passive radiators. For free space performance, two types of excitations were used--waveguide port and a coaxial probe. The coaxial probe significantly improved both the bandwidth and radiation efficiency. The center frequency of all the designs was close to 60 GHz with a bandwidth of more than 5 GHz. These designs achieved a maximum gain of 8.47 dB, 10 dB, and 9.73 dB while the radiation efficiency was around 94%. For body-centric applications, these antennas were simulated at two different distances from a human torso phantom using a coaxial probe. The torso phantom was modeled by taking three layers of the human body--skin, fat, and muscle. Millimeter waves have low penetration depth in the human body as a result antenna performance is less affected. A negligible shift of return loss curves was observed. Radiation efficiencies dropped at the closest distance to the phantom and at the furthest distance, the efficiencies increased to free space values. On the three layers human body phantom, all three different antenna designs show directive radiation patterns towards off the body. All three designs exhibited similar results in terms of center frequency and efficiency but varied slightly by either having better bandwidth or maximum gain. [ABSTRACT FROM AUTHOR]

Although the 60 GHz band meets the higher data rate demands for various wireless applications, large path losses and small size of 5 mm free-space wavelength makes the design, fabrication, packaging, and measurement of 60 GHz antenna arrays challenging. In this letter, we present a low-cost and high-efficiency patch antenna array fabricated using a printed circuit board (PCB) process. As the mini-connector size is larger than unit-cell at 60 GHz, it poses challenges for separate feeding for each array element. This optimized configuration not only addresses the mini-connector assembly shortcoming for off-chip antenna measurements in a laboratory environment but also permits future direct flip-chip integration on a transceiver. Embedded thin-film resistors are first used to fabricate 50 Ω termination and calibration elements on the same board, thus removing associated lossy and bulky external loads and calibration kit. Next, a highly precise robotic antenna measurement system is used to complete the challenging task of measuring far-field pattern at 60 GHz. The proposed 5×5 antenna array is matched at 60 GHz with the −10 dB bandwidth of 3.6 GHz (6%). The peak realized gain of the 5×5 array is 18.5 dBi, and the measured boresight efficiency is 85% at 60 GHz. Furthermore, the simulated maximum scanning volume is ±40° in the E-plane and ±45° in the H-plane. Therefore, the proposed 60 GHz antenna array maintains a low-cost, high-efficiency moderate scanning range with a potential for easy on-chip integration for future communication and sensing applications. [ABSTRACT FROM AUTHOR]

Wireless networks operating in the 60 GHz band have the potential to provide very high throughput but face a number of challenges (e.g., high attenuation, beam training, and coping with mobility) which are widely accepted but often not well understood in practice. Understanding these challenges, and especially their actual impact on consumer-grade hardware is fundamental to fully exploit the high physical layer rates in the 60 GHz band. To this end, we perform an extensive measurement campaign using two commercial off-the-shelf 60 GHz routers in real-world environments. Our results allow us to revisit a range of issues and provide much deeper insights into the reasons for specific performance compared to prior work on performance characterization. Further, our study goes beyond basic link characterization and explores for the first time practical considerations such as coverage and access point deployment. While some of our observations are expected, we also obtain highly surprising insights that challenge the prevailing wisdom in the community. We derive the shortcomings of current commercial 60 GHz devices, and the fundamental problems that remain open on the way to fast and efficient 60 GHz networking. [ABSTRACT FROM AUTHOR]