A novel low-swing voltage driver design and the analysis of its robustness to the effects of process variation and external disturbances

arket forces are continually demanding devices with increased functionality/unit area; these demands have been satisfied through aggressive technology scaling which, unfortunately, has impacted adversely on the global interconnect delay subsequently reducing system performance. Line drivers have been used to mitigate the problems with delay; however, these have a large power consumption. A solution to reducing the power dissipation of the drivers is to use lower supply voltages. However, by adopting a lower power supply voltage, the performance of the line drivers for global interconnects is impaired unless low-swing signalling techniques are implemented. Low-swing signalling techniques can provide high speed signalling with low power consumption and hence can be used to drive global on-chip interconnect. Most of the proposed low-swing signalling schemes are immune to noise as they have a good SNR. However, they tend to have a large penalty in area and complexity as they require additional circuitry such as voltage generators and low-Vth devices. Most of the schemes also incorporate multiple Vdd and reference voltages which increase the overall circuit complexity. A diode-connected driver circuit has the best attributes over other low-swing signalling techniques in terms of low power, low delay, good SNR and low area overhead. By incorporating a diode-connected configuration at the output, it can provide high speed signalling due to its high driving capability. However, this configuration also has its limitations as it has issues with its adaptability to process variations, as well as an issue with leakage currents. To address these limitations, two novel driver schemes have been designed, namely, nLVSD and mLVSD, which, additionally, have improvements in performance and power consumption. Comparisons between the proposed schemes with the existing diode-connected driver circuits (MJ and DDC) showed that the nLVSD and mLVSD drivers have approximately 46% and 50% less delay. The name MJ originates from the driver’s designer called Juan A. Montiel-Nelson, while DDC stands for dynamic diode-connected. In terms of power consumption, the nLVSD and mLVSD drivers also produce 43% and 7% improvement. Additionally, the mLVSD driver scheme is the most robust as its SNR is 14 to 44% higher compared to other diode-connected driver circuits. On the other hand, the nLVSD driver has 6% lower SNR compared to the MJ driver, even though it is 19% more robust than the DDC driver. However, since its SNR is still above 1, its improved performance and reduced power consumption, as well other advantages it has over other diode-connected driver circuits can compensate for this limitation. Regarding the robustness to external disturbances, the proposedmdriver circuits are more robust to crosstalk effects as the nLVSD and mLVSD drivers are approximately 35% and 7% more robust than other diode-connected drivers. Furthermore, the mLVSD driver is 5%, 33% and 47% more tolerant to SEUs compared to the nLVSD, MJ and DDC driver circuits respectively, whilst the MJ and DDC drivers are 26% and 40% less tolerant to SEUs iii compared to the nLVSD circuit. A comparison between the four schemes was also undertaken in the presence of ±3σ process and voltage (PV) variations. The analysis indicated that both proposed driver schemes are more robust than other diode-connected driver schemes, namely, the MJ and DDC driver circuits. The MJ driver scheme deviates approximately 18% and 35% more in delay and power consumption compared to the proposed schemes. The DDC driver has approximately 20% and 57% more variations in delay and power consumption in comparison to the proposed schemes. In order to further improve the robustness of the proposed driver circuits against process variation and environmental disturbances, they were further analysed to identify which process variables had the most impact on circuit delay and power consumption, as well as identifying several design techniques to mitigate problems with environmental disturbances. The most significant process parameters to have impact on circuit delay and power consumption were identified to be Vdd, tox, Vth, s, w and t. The impact of SEUs on the circuit can be reduced by increasing the bias currents whilst design methods such as increasing the interconnect spacing can help improve the circuit robustness against crosstalk. Overall it is considered that the proposed nLVSD and mLVSD circuits advance the state of the art in driver design for on-chip signalling applications.EThOS - Electronic Theses Online ServiceGBUnited Kingdo

Review of Switched Beamforming Networks for Scannable Antenna Application towards Fifth Generation (5G) Technology

The next generation wireless network (5G) addresses the evolution beyond mobile internet to massive Internet-of-Things (IoT) which will take off from 2019/2020 onwards. The essential design features in 5G wireless network system are massive multiple-input and multiple-output (MIMO) and steerable antenna array. The higher capacity, lower power transmission and larger system coverage offered by upcoming 5G technology can be realized using switched-beam antenna such as Butler matrix, Rotman lens, Blass matrix and Nolen matrix. Review of their design features and performance results will be compared in this article. Butler matrix can be the best approach owing to low complexity, orthogonal beams and less components utilization

Miniaturized 4 x 4 switched-beam butler matrix with bandwidth enhancement for 5G communication system

A 4 x 4 Butler Matrix (BM) without phase shifter is proposed to provide bandwidth enhancement and size reduction by removing a conventional 0 dB/90⁰ crossover, two 0⁰ phase shifters and two 45 phase shifters. Two proposed 3 dB/45⁰ patch couplers replace the combination of two conventional 3 dB/90⁰ branch-line couplers and two 45⁰ phase shifters, whilst a modified0 dB/0⁰ crossover removes two 0⁰ phase shifters from the conventional BM. The -10 dB fractional bandwidths of reflection coefficients and isolations for the proposed BM are 18.46% in simulation and measurement. The -6 dB ± 1.5 dB average transmission coefficient and +45⁰, �135�, +135⁰and +45⁰ of output phase differences with 1.8� average phase imbalance are accomplished at 6.5 GHz. The simulated and measured scattering parameters (S parameters) and phase differences are in close compliance with each other. Four switched-beams pointed at +15⁰, -50⁰, +50⁰ and +15⁰ are developed by integrating the proposed BM with inset feeding patch antennas. The proposed BM is miniaturized by 51.56%, whilst the bandwidth performance is enhanced by 9.7% compared to the conventional BM. Hence, this compact BM is a promising candidate for the fifth generation (5G) communication system

Multi-user mmWave MIMO channel estimation with hybrid Beamforming over frequency selective fading channels

In multi-user millimeter wave (mmWave) multiple input multiple output (MIMO) systems, obtaining accurate information/knowledge regarding the channel state is crucial to achieving multi-user interference cancellation and reliable beamforming (BF)-to compensate for severe path loss. This knowledge is nonetheless very challenging to acquire in practice since large antenna arrays experience a low signal-to-noise ratio (SNR) before BF. In this paper, a multi-user channel estimation (CE) scheme namely generalized-block compressed sampling matching pursuit (G-BCoSaMP), is proposed for multi-user mmWave MIMO systems over frequency selective fading channels. This scheme exploits the cluster-structured sparsity in the angular and delay domain of mmWave channels determined by the actual spatial frequencies of each path. As the corresponding spatial frequencies of multi-user mmWave MIMO systems with Hybrid BF often fall between the discrete Fourier transform (DFT) bins due to the continuous Angle of Arrival (AoA)/Angle of Departure (AoD), the proposed G-BCoSaMP algorithm can address the resulting power leakage problem. Simulation results show that the proposed algorithm is effective and offer a better CE performance in terms of MSE when compared to the generalized block orthogonal matching pursuit (G-BOMP) algorithm that does not possess a pruning step

Single-Event-Upset Sensitivity Analysis on Low-Swing Drivers

Technology scaling relies on reduced nodal capacitances and lower voltages in order to improve performance and power consumption, resulting in significant increase in layout density, thus making these submicron technologies more susceptible to soft errors. Previous analysis indicates a significant improvement in SEU tolerance of the driver when the bias current is injected into the circuit but results in increase of power dissipation. Subsequently, other alternatives are considered. The impact of transistor sizes and temperature on SEU tolerance is tested. Results indicate no significant changes in Qcrit when the effective transistor length is increased by 10%, but there is an improvement when high temperature and high bias currents are applied. However, this is due to other process parameters that are temperature dependent, which contribute to the sharp increase in Qcrit. It is found that, with temperature, there is no clear factor that can justify the direct impact of temperature on the SEU tolerance. Thus, in order to improve the SEU tolerance, high bias currents are still considered to be the most effective method in improving the SEU sensitivity. However, good trade-off is required for the low-swing driver in order to meet the reliability target with minimal power overhead

On the spectral-efficiency of low-complexity and resolution hybrid precoding and combining transceivers for mmWave MIMO systems

Millimeter wave (mmWave) multiple-input-multiple-output (MIMO) systems will almost certainly use hybrid precoding to realize beamforming with few numbers of RF chains to reduce energy consumption, but require low complexity technique to improve spectral efficiency. While energy-efficient hybrid analog/digital precoders and combiners designs can subdue the high pathloss inherent in mmWave channels, they assume the use of infinite- (or high-) resolution phase shifters to realize the analog precoder and combiner pair which results in high hardware cost and power consumption. One promising solution is to employ the use of low-resolution phase shifters. In this paper, we first diverse the exploration of multiple candidates of array response vectors, to propose low-complexity hybrid precoder and combiner (LcHPC) design via stage-determined matching pursuit (SdMP) namely, LcHPC-SdMP for pursuing better achievable rate for mmWave MIMO systems. We initially decouple the joint optimization over hybrid precoders and combiners into two separate sparse recovery problems. Specifically, LcHPC-SdMP algorithm revises the identification step of orthogonal matching pursuit (OMP) to the selection of multiple "correct" column indices of the matrix of array response vectors, per iteration. Then adds a pruning step-after satisfying a sparsity level condition, to iteratively refine the sparse solution which aids in further accelerating the algorithm, by requiring fewer iterations. We then propose an algorithm which iteratively designs low-resolution (two-bit) hybrid analog-digital precoder and combiner (LrHPC), for pursuing efficiency while maximizing spectral efficiency. Simulation results demonstrate that the proposed LcHPC-SdMP algorithm performs very close to its full-digital precoding and achieves better spectral efficiency over state-of-the-art algorithms with a substantially reduced number of iteration than the recently proposed schemes. In addition, simulation results also reveal that the achievable rate of the proposed LrHPC algorithm is higher than those of the existing algorithms under consideration

A framework for preventing unauthorized drone intrusions through radar detection and GPS spoofing

The increasing use of Global Positioning System (GPS)-based autonomous drones in various civilian and military applications has raised concerns about malicious or unintentionally harmful activities that can be carried through them. It is necessary to detect these intruding drones within protected areas and prevent their unauthorized access by denying them entry. We propose a framework that combines the detection of intruding drones using an L-band radar and then counters by transmitting fake GPS coordinates toward the drones, effectively redirecting them. This article explains the setup required to add to an existing monostatic radar that provides two-dimensional information, i.e., range and azimuth information, to enable the proposed setup to get the elevation angle of the drone. We propose a linear array design using digital receive-only beamforming techniques in the elevation domain to compute the elevation angle in addition to the range, velocity, and azimuth information being provided by the monostatic radar to get complete information about the intruding drone. The simulation of drone detection is followed by an examination of the impact of transmitting fabricated GPS coordinates to the drone. Experimental verification has been conducted to validate both the digital beamforming algorithm and the spoofing technique. This approach blocks the reception of actual GPS signals in the drone and replaces the drone's GPS coordinates with alternative, desired coordinates. The proposed framework can be used to prevent unauthorized drone intrusions in the protected area

Design of a negative conductance dielectric resonator oscillator for X-band applications

An X-band tunable microwave low-phase noise planar oscillator employing a novel-fed dielectric resonator (DR) with a single transistor has been investigated and realized. A ZrSnTi oxide composite ceramic-based DR with dielectric permittivity of 95 enclosed in a metallic cavity with an unloaded Q factor of 5,000 at 10 GHz is proposed. The resonant frequency affinity with respect to geometric parameters is established by using the compensation technique based on dual negative conductance feedback, the outputs of which are combined via a Wilkinson power divider (WPD). The feedback parallel-coupled DR oscillator is incorporated into a laminate microwave board using the photolithographic technique. The oscillator includes a pseudomorphic low noise amplifier based on a high-electron-mobility transistor. Hence, the proposed oscillator with mechanic tuning is measured, and the results show that DR resonates at TE01d mode with frequency of 10 GHz. The measured phase noise of the oscillator is –81.03 dBc/Hz at a 100 kHz offset