In this paper, a new balanced-to-balanced power divider/combiner is proposed. By using matrix transformation, two three-port networks for the odd- and even-mode circuit models are deduced, based on ...the constraint rules of the mixed-mode S -parameters. In order to satisfy the two required scattering matrices simultaneously, the resistances of lumped elements, the characteristic impedances and electrical length of transmission lines are selected appropriately. Then, a planar microstrip structure is designed to realize the proposed balanced-to-balanced power divider/combiner with equal power division. The theoretical, simulated and measured results all show a good mixed-mode performance. In the measurement, the maximum differential-mode transmission coefficient is -3.2 dB, the best differential-mode isolation is 47.2 dB, and the fractional bandwidth of its operating band is approximately 20.8%.
This article presents a spatial-temporal single harmonic switching (STHS) transmitter array architecture with enhanced efficiency in the power back-off (PBO) region. STHS is an electromagnetic ...circuit co-designed and jointly optimized transmitter array that realizes beamforming and back-off power generation at the same time. The temporal dimension is originally added in STHS to achieve back-off efficiency enhancement, which can be combined with conventional PBO enhancement methods such as Doherty amplifiers and envelope tracking. The design is validated through a simulation of a two-stage power amplifier (PA) in 65-nm CMOS at 77 GHz, which achieves a peak drain efficiency (DE) of 24.2%, a 22% DE at 3 dB PBO, 16% DE at 6 dB PBO, and 10.2% at 9 dB PBO. The efficiency exhibits a 57% improvement at 3 dB PBO, 100% improvement at 6 dB PBO, and 190% improvement at 9 dB PBO compared with class A/B amplifiers.
In this paper, several important aspects associated with the modeling and fast simulation of global multiwalled carbon nanotube (MWCNT) interconnects are studied in detail. The MWCNTs are ...characterized by both the multiconductor circuit (MCC) model and the simplified equivalent single conductor (ESC) model. With two different circuit models, the impacts of intershell tunneling conductance and imperfect contact resistance on electrical performance of both single and coupled MWCNT interconnects are investigated. Based on the ESC model, an efficient algorithm combining modal decoupling and delay extraction techniques is presented for fast transient simulation of MWCNT interconnects. The numerical results illustrate that different locations of imperfect contact resistance may exert apparent effects on transient response of MWCNT interconnects. Nevertheless, these effects can be reduced by intershell tunneling conductance in the MCC model. The accuracy and efficiency of the proposed method are also demonstrated by the numerical examples.
Antenna-in-package (AiP) technology, in which there is an antenna (or antennas) with a transceiver die (or dies) in a standard surface-mounted device, represents an important antenna and packaging ...technology achievement in recent years. AiP technology has been widely adopted by chipmakers for 60-GHz radios and gesture radars. It has also found applications in 77-GHz automotive radars, 94-GHz phased arrays, 122-GHz imaging sensors, and 300-GHz wireless links. It is believed that AiP technology will also provide elegant antenna and packaging solutions to the fifth generation and beyond operating in the lower millimeter-wave (mmWave) bands. Thus, one can conclude that AiP technology has emerged as the mainstream antenna and packaging technology for various mmWave applications. This article will provide an overview of the development of AiP technology. It will consider antennas, packages, and interconnects for AiP technology. It will show that the antenna choice is usually based on those popular antennas that can be easily designed for the application, that the package choice is governed for automatic assembly, and that the materials and processes choices involve tradeoffs among constraints, such as electrical performance, thermal-mechanical reliability, compactness, manufacturability, and cost. This article also shows a probe-based setup to measure mmWave AiP impedance and radiation characteristics. It goes on to give AiP examples implemented, respectively, in a low-temperature co-fired ceramic, an embedded wafer level ball grid array process, and a high-density interconnect processes. Finally, this article will summarize and present some recommendations on research topics to further the state of the art of AiP technology.
An electrically steerable parasitic array radiator in package based on liquid crystal (LC) is presented. It consists of one main and two parasitic inverted microstrip patch elements on an embedded LC ...layer with direct current bias. The antenna is designed to operate under the voltage mode at Ka-band. By varying the induced voltages on parasitic elements, the main beam can be steered to the desired direction. Measured results show that the pattern can be steered from -27° to +29° continuously in the H-plane at 28 GHz. The peak realized gain is 6.03 dBi with 1 dB variation within the steering range. The array achieves an 8.3% impedance bandwidth and avoids both large direct current power consumption and complicated bias scheme, making it a good antenna candidate for millimeter-wave 5G access point applications.
The equivalent surface impedance (ESI)-based mixed potential integral equation (MPIE) is proposed in this paper for parameter extraction of 3-D interconnects. Boundary integral equations (BIEs) ...describing the conductor region and the nonconductor region are utilized to derive the ESI model, which incorporates with an MPIE to simplify the electromagnetic simulation. For large-scale problems, the solution of MPIE is accelerated by the hierarchical matrix (H-matrix) algorithm. Since the interconnect problems usually have multiple ports, the method of moments discretization of MPIE leads to the matrix equation with multiple right-hand sides, which is efficiently solved by the H-LU-based direct solution. Procedures for H-matrix are optimized to improve the overall efficiency. The proposed method to optimize H-matrix benefits both the H-matrix construction and the H-LU procedures. The complexities of the CPU time and memory cost for the construction of the optimized H-matrix are of O(N log N), and the complexity for the direct H-LU solution is of O(N log 2 N). Numerical results demonstrate that the proposed method is both accurate and efficient in a broadband frequency, which is suitable for modeling of 3-D interconnects and on-chip passive structures.
A challenge for frequency-reconfigurable antennas is how to realize miniaturized structures while preserving satisfying radiation performance in whole operation bandwidth. To address this problem, we ...apply planar periodic slow-wave structure (PSWS) with controlled dispersion features for miniaturization of antenna. Due to the subwavelength property and large propagation constant, this design holds a much more compact size than conventional microstrip structures. The proposed antenna consists of a double-layered dielectric substrate with the tunable patch on the top and a bias network combining with the feeding part on the bottom. The operating frequency is electronically controlled by the varactors shortened to the ground on nonradiating edges. It ranges from 4.87 to 5.52 GHz when the bias voltage varies from 9 to 16 V. Both simulated and measured results show that the proposed antenna maintains acceptable gains and similar radiation patterns while shrinking the size effectively. The proposed miniaturized and frequency-reconfigurable antenna holds potential applications in the ultracompact frequency hopping communication systems.
This paper presents a novel time-domain integration method for transient analysis of nonuniform multiconductor transmission lines (MTLs). It can solve the time response of various kinds of ...transmission lines with arbitrary coupling status. The spatial discretization in this method is the same as the finite-difference time-domain (FDTD) algorithm. However, in order to eliminate the Courant-Friedrich-Levy condition constraint, a precise time-step integration method is utilized in time-domain calculation. It gives an analytical solution in the time domain for the spatial discretized Telegrapher's equations with linear boundary conditions. Large time steps can be adopted in the integration process to achieve accurate results efficiently. In the analysis of transmission lines with frequency-dependent parameters, a passive equivalent model is introduced, which leads to the similar semidiscrete model as that for the frequency-independent case. In addition, a rigorous proof of the passivity of the model is provided. Numerical examples are presented to demonstrate the accuracy and stability of the proposed method.
In this paper, the laminated conductor technology is first introduced to planar-integrated transmission lines. The laminated conductor is composed of multilayers of metal and insulator, which has a ...lower conductor loss than a solid conductor. Based on the silicon-based micro electromechanical system technology, a laminated coplanar waveguide (CPW) with wide bandwidth and low loss is proposed, which uses a laminated conductor for signal lines and grounds. A laminated CPW and its transition are designed, fabricated, and measured. The simulation results show that the laminated CPW with many insulator layers has a low conductor loss. The measurement results illustrate that the average insertion loss of the laminated CPW is 0.65 dB from DC to 40 GHz, which is 44.4% smaller than that of the solid CPW.
In this paper, a new beam reconfigurable antenna is proposed for THz application, which is based on a switchable high-impedance surface (HIS) using a single-layer graphene. The effects of impurity ...density and gate voltage on the conductivity of graphene are utilized, and the switchable reflection characteristic of the graphene-based HIS is observed. Then the THz antenna is designed over this switchable HIS. By applying different voltages for different rows of HIS units, the antenna beam can be reconfigurable. The performance of the antenna is analyzed with its reflection coefficient, radiation pattern, and input impedance. The radiation beam of the antenna can vary in a range of ±30° as demonstrated by the simulated results.
