高速电路中地弹噪声抑制的研究

研究了高速电路领域中的一类重要的电源完整性问题,即电源地平面之间激发的地弹噪声问题。地 弹噪声的存在严重破坏了电源/ 地平面的完整性,导致供电电压幅度的不稳定,严重之时甚至导致电路的误判。针 对这一问题,设计了一种超宽带电磁带隙结构。实验结果表明,这种电磁带隙结构可以在0. 5 ~5. 5GHz(11 倍频程) 频段内实现优于30dB 的噪声抑制能力。文章还探讨了带隙结构作为电源平面时信号传输的完整性。研究表明,如 果电路工作频率高达GHz 或更高,在电源/ 地平面采用这种带隙结构,可以有效地避免地弹噪声带来的影响,并保证 电源和信号的完整性。     

Multi‐stack Technique for a Compact and Wideband EBG Structure in High‐Speed Multilayer Printed Circuit Boards

We propose a novel multi‐stack (MS) technique for a compact and wideband electromagnetic bandgap (EBG) structure in high‐speed multilayer printed circuit boards. The proposed MS technique efficiently converts planar EBG arrays into a vertical structure, thus substantially miniaturizing the EBG area and reducing the distance between the noise source and the victim. A dispersion method is presented to examine the effects of the MS technique on the stopband characteristics. Enhanced features of the proposed MS‐EBG structure were experimentally verified using test vehicles. It was experimentally demonstrated that the proposed MS‐EBG structure efficiently suppresses the power/ground noise over a wideband frequency range with a shorter port‐to‐port spacing than the unit‐cell length, thus overcoming a limitation of previous EBG structures.     

Application of VSI‐EBG Structure to High‐Speed Differential Signals for Wideband Suppression of Common‐Mode Noise

In this paper, we present wideband common‐mode (CM) noise suppression using a vertical stepped impedance electromagnetic bandgap (VSI‐EBG) structure for high‐speed differential signals in multilayer printed circuit boards. This technique is an original design that enables us to apply the VSI‐EBG structure to differential signals without sacrificing the differential characteristics. In addition, the analytical dispersion equations for the bandgap prediction of the CM propagation in the VSI‐EBG structure are extracted, and the closed‐form expressions for the bandgap cutoff frequencies are derived. Based on the dispersion equations, the effects of the impedance ratio, the EBG patch length, and via inductances on the bandgap of the VSI‐EBG structure for differential signals are thoroughly examined. The proposed dispersion equations are verified through agreement with the full‐wave simulation results. It is experimentally demonstrated that the proposed VSI‐EBG structure for differential signaling suppresses the CM noise in the wideband frequency range without degrading the differential characteristics.     

Bandwidth Enhancement for SSN Suppression Using a Spiral‐Shaped Power Island and a Modified EBG Structure for a λ/4 Open Stub

This paper proposes a spiral‐shaped power island structure that can effectively suppress simultaneous switching noise (SSN) when the power plane drives high‐speed integrated circuits in a small area. In addition, a new technique is presented which greatly improves the resonance peaks in a stopband by utilizing λ/4 open stubs on a conventional periodic electromagnetic bandgap (EBG) power plane. Both proposed structures are simulated numerically and experimentally verified using commercially available 3D electromagnetic field simulation software. The results demonstrate that they achieve better SSN suppression performance than conventional periodic EBG structures.     

A novel power plane with super-wideband elimination of ground bounce noise on high speed circuits

A novel L-bridged electromagnetic bandgap (EBG) power/ground planes is proposed with super-wideband suppression of the ground bounce noise (GBN) from 600Mz to 4.6GHz. The L-shaped bridge design on the EBG power plane not only broadens the stopband bandwidth, but also can increase the mutual coupling between the adjacent EBG cells by significantly decreasing the gap between the cells. It is found the small gap design can prevent from the severe degradation of the signal quality for the high-speed signal referring to the perforated EBG power plane. The excellent GBN suppression performance with keeping reasonably good signal integrity for the proposed structure is validated both experimentally and numerically. Good agreement is seen.     

Frequency shift filter‐based multi‐carrier transceiver

It is well known that orthogonal frequency division multiplexing (OFDM) is sensitive to carrier frequency offset (CFO) and suffers from a high peak‐to‐average ratio. In addition, the performance of OFDM is severely affected by strong co‐channel interference and strong narrowband interference. To mitigate the limitations of OFDM, we propose a new multi‐carrier transceiver based on frequency‐shift filter. A frequency‐shift filter can separate spectrally overlapping sub‐carrier signals by exploiting the spectral correlation inherent in the cyclostationary modulated signals. To increase spectral efficiency, we increase the percentage of spectral overlap between two adjacent sub‐channels. We derive an upper bound and a lower bound on the bit error rate performance of the proposed multi‐carrier transceiver in additive white Gaussian noise channel and frequency‐nonselective Rayleigh fading channel, respectively. Compared with OFDM, our simulation results show that the proposed multi‐carrier transceiver is much less sensitive to CFO and has a lower peak‐to‐average ratio; moreover, without any additional interference suppression technique, the proposed transceiver has the advantage of being able to mitigate strong co‐channel interference with CFO from the intended multi‐carrier signal and mitigate strong narrowband interference in additive white Gaussian noise channel and in Rayleigh fading channel in which a large CFO between the transmitted signal and the received signal often occurs. Copyright © 2011 John Wiley & Sons, Ltd.     

一种适用于同步开关噪声抑制的共面电磁带隙新结构

该文根据电磁带隙结构的带隙形成机理及共面电磁带隙结构等效电路分析模型,通过引入新型的C-型桥接连线及开槽设计,提出了一种适用于高速电路同步开关噪声(SSN)抑制的带有狭缝的共面C-型桥电磁带隙(CBS-EBG)结构。实测结果表明,在抑制深度为?40 dB时,阻带范围为296 MHz~15 GHz,与LBS-EBG结构相比,在保持高频段SSN抑制性能的同时,阻带下限截止频率由432 MHz下降至296 MHz,有效降低了带隙中心频率。研究了局部拓扑下的信号传输特性,结果表明,当采用局部拓扑并选择合适的走线策略时,该结构在保持良好的SSN抑制性能的同时,能够实现较好的信号完整性。     

一种适用于高速电路中SSN抑制的紧凑型电磁带隙新结构

该文根据电磁带隙(EBG)结构的带隙形成机理以及共面EBG结构的等效电路,提出了一种适用于高速电路中同步开关噪声(SSN)抑制的紧凑型EBG结构,使用Ansoft HFSS对该结构进行仿真分析。仿真结果表明在抑制深度为-30 dB时,阻带范围为0.6-6.4 GHz,阻带带宽为5.8 GHz,与传统的L-bridge结构相比,阻带带宽增加了1.8 GHz,相对带宽增加了45%,实现了较低的带隙中心频率以及较宽的阻带带宽,并用Ansoft Designer通过时域仿真验证该结构具有较好的信号完整性。     

一种新型多周期平面电磁带隙结构

根据不同周期平面电磁带隙(EBG)结构所具有的不同带隙特性以及平面EBG结构的等效电路,提出一种新型多周期平面EBG结构。通过Ansoft HFSS软件对该EBG结构的电磁带隙特性进行仿真验证。结果表明:所提出的EBG结构抑制深度为-30dB时,阻带范围为0.7～8.4GHz,阻带宽度为7.7GHz.相对于传统大周期和小周期平面EBG结构,其阻带宽度分别增加2.1GHz和1.2GHz.仿真结果也表明新型EBG结构可以有效抑制同步开关噪声(SSN),并为展宽平面EBG结构的禁带带宽提供一种新方法。最后,通过时域仿真验证新结构具有较好的信号完整性。     

Two‐Microphone Generalized Sidelobe Canceller with Post‐Filter Based Speech Enhancement in Composite Noise

This paper describes an algorithm to suppress composite noise in a two‐microphone speech enhancement system for robust hands‐free speech communication. The proposed algorithm has four stages. The first stage estimates the power spectral density of the residual stationary noise, which is based on the detection of nonstationary signal‐dominant time‐frequency bins (TFBs) at the generalized sidelobe canceller output. Second, speech‐dominant TFBs are identified among the previously detected nonstationary signal‐dominant TFBs, and power spectral densities of speech and residual nonstationary noise are estimated. In the final stage, the bin‐wise output signal‐to‐noise ratio is obtained with these power estimates and a Wiener post‐filter is constructed to attenuate the residual noise. Compared to the conventional beamforming and post‐filter algorithms, the proposed speech enhancement algorithm shows significant performance improvement in terms of perceptual evaluation of speech quality.     

Binary Power Amplifier with 2‐Bit Sigma‐Delta Modulation Method for EER Transmitter

A novel power amplifier for a polar transmitter is proposed to achieve better spectral performance for a wideband envelope signal. In the proposed scheme, 2‐bit sigma‐delta (ΣΔ) modulation of the envelope signal is introduced, and the power amplifier configuration is modified in a binary form to accommodate the 2‐bit digitized envelope signals. The 2‐bit ΣΔ modulator lowers the noise of the envelope signal by fine quantization and thus enhances the spectral property of the RF signal. The Ptolemy simulation results of the proposed structure show that the spectral noise is reduced by 10 dB in a full transmit band of the EDGE system. The dynamic range is also enhanced. Since the performance is improved without increasing the over‐sampling ratio, this technique is best suited for wireless communication with high data rates.     

Power allocation scheme based on sum capacity maximization for signal‐to‐leakage‐and‐noise ratio precoded multiuser multiple‐input single‐output downlink

This paper proposes a power allocation scheme to maximize the sum capacity of all users for signal‐to‐leakage‐and‐noise ratio (SLNR) precoded multiuser multiple‐input single‐output downlink. The designed scheme tries to explore the effect of the power allocation for the SLNR precoded multiuser multiple‐input single‐output system on sum capacity performance. This power allocation problem can be formulated as an optimization problem. With high signal‐to‐interference‐plus‐noise ratio assumption, it can be converted into a convex optimization problem through the geometric programming and hence can be solved efficiently. Because the assumption of high signal‐to‐interference‐plus‐noise ratio cannot be always satisfied in practice, we design a globally optimal solution algorithm based on a combination of branch and bound framework and convex relaxation techniques. Theoretically, the proposed scheme can provide optimal power allocation in sum capacity maximization. Then, we further propose a judgement‐decision algorithm to achieve a trade‐off between the optimality and computational complexity. The simulation results also show that, with the proposed scheme, the sum capacity of all the users can be improved compared with three existing power allocation schemes. Meanwhile, some meaningful conclusions about the effect of the further power allocation based on the SLNR precoding have been also acquired. The performance improvement of the maximum sum capacity power allocation scheme relates to the transmit antenna number and embodies different variation trends in allusion to the different equipped transmit antenna number as the signal‐to‐noise ratio (SNR) changes.Copyright © 2013 John Wiley & Sons, Ltd.     

EBG combined isolation slots with a bridge on the ground for noise suppression

In this paper, a coplanar electromagnetic bandgap (EBG) structure is presented to realise with L-bridge unit cell on the power plane that is combined isolation slots with straight/meander-bridge on the ground plane. The proposed structure with meander-bridge on the ground plane possesses an ultra-wide band gap from 0.22 GHz to 20 GHz with isolation below ?30 dB, which is remarkable better than traditional EBG. The lumped equivalent-circuit model for the structure is presented and analysed to explain the mechanism of the improvement of noise suppression. The cut-off frequency for the proposed structure is obtained by theoretical analysis. It is shown that the increase of equivalent inductance of the bridge influences the cut-off frequency. The meander-bridge on the ground plane is adopted to broaden the stopband and significantly enhance the suppression depth. The validity of the presented structure is verified by the simulation compared to the measurement.     

一款紧凑增强型可变阻抗电磁带隙结构

基于传统AI-EBG结构,提出了一种小尺寸的增强型电磁带隙结构,实现了从0.5~9.4 GHz的宽频带-40 dB噪声抑制深度,且下截止频率减少到数百MHz,可有效抑制多层PCB板间地弹噪声。文中同时研究了EBG结构在高速电路应用时的信号完整性问题,使用差分信号方案可改善信号完整性。     

A Double-Surface Electromagnetic Bandgap Structure With One Surface Embedded in Power Plane for Ultra-Wideband SSN Suppression

In this letter, a double-surface electromagnetic bandgap (EBG) structure with one EBG surface embedded in power plane is proposed for ultra-wideband simultaneous switching noise (SSN) suppression in printed circuit boards. The SSN suppression bandwidth is broadened to wider than 30 GHz with a low start frequency by combining traditional EBG structure and the coplanar EBG structure which is embedded in the power plane. Because the coplanar EBG surface is embedded in the power plane, no additional metal layer is introduced by the double-surface EBG structure. Simulations and measurements are performed to verify the broadband SSN suppression, high performance is observed.     

Partial uniplanar compact electromagnetic bandgap combined with high-impedance surface to suppress simultaneous switching noise

Proposed is a design for a partial uniplanar compact electromagnetic bandgap (UC-EBG) structure, in conjunction with a high-impedance surface (HIS), to suppress simultaneous switching noise (SSN) over the wide frequency range 0.38-15.494-GHz. Different from the conventional methods, which use an EBG plane, the proposed structure uses only two UC-EBGs at the excitation and receiving ports to suppress SSN. This technique can be applied to sensitive circuits to maintain their power integrity. The other region maintains good signal integrity when a signal return path is referenced to an EBG plane.     

Design and implementation of electromagnetic band‐gap embedded antenna for vehicle‐to‐everything communications in vehicular systems

We proposed a novel electromagnetic band‐gap (EBG) cell‐embedded antenna structure for reducing the interference that radiates at the antenna edge in wireless access in vehicular environment (WAVE) communication systems for vehicle‐to‐everything communications. To suppress the radiation of surface waves from the ground plane and vehicle, EBG cells were inserted between micropatch arrays. A simulation was also performed to determine the optimum EBG cell structure located above the ground plane in a conformal linear microstrip patch array antenna. The characteristics such as return loss, peak gain, and radiation patterns obtained using the fabricated EBG cell‐embedded antenna were superior to those obtained without the EBG cells. A return loss of 35.14 dB, peak gain of 10.15 dBi at 80°, and improvement of 2.037 dB max at the field of view in the radiation beam patterns were obtained using the proposed WAVE antenna.     

Field programmable analog arrays for implementation of generalized nth‐order operational transconductance amplifier‐C elliptic filters

This study presents a new architecture for a field programmable analog array (FPAA) for use in low‐frequency applications, and a generalized circuit realization method for the implementation of nth‐order elliptic filters. The proposed designs of both the FPAA and elliptic filters are based on the operational transconductance amplifier (OTA) used in implementing OTA‐C filters for biopotential signal processing. The proposed FPAA architecture has a flexible, expandable structure with direct connections between configurable analog blocks (CABs) that eliminates the use of switches. The generalized elliptic filter circuit realization provides a simplified, direct synthetic method for an OTA‐C symmetric balanced structure for even/odd‐nth‐order low‐pass filters (LPFs) and notch filters with minimum number of components, using grounded capacitors. The filters are mapped on the FPAA, and both architectures are validated with simulations in LTspice using 90‐nm complementary metal‐oxide semiconductor (CMOS) technology. Both proposed FPAA and filters generalized synthetic method achieve simple, flexible, low‐power designs for implementation of biopotential signal processing systems.     

Rakeness with block sparse Bayesian learning for efficient ZigBee‐based EEG telemonitoring

Future healthcare systems are shifted toward long‐term patient monitoring using embedded ultra‐low power devices. In this paper, the strengths of both rakeness‐based compressive sensing (CS) and block sparse Bayesian learning (BSBL) are exploited for efficient electroencephalogram (EEG) transmission/reception over wireless body area networks. A binary sensing matrix based on the rakeness concept is used to find the most energetic signal directions. A balance is achieved between collecting energy and enforcing restricted isometry property to capture the underlying signal structure. Correct presentation of the EEG oscillatory activity, EEG wave shape, and main signal characteristics is provided using the discrete cosine transform based BSBL, which models the intra‐block correlation. The IEEE 802.15.4 wireless communication technology (ZigBee) is employed, since it targets low data rate communications in an energy efficient manner. To alleviate noise and channel multipath effects, a recursive least square based equalizer is used, with an adaptation algorithm that continually updates the filter weights using successive input samples. For the same compression ratio (CR), results indicate that the proposed system permits a higher reconstruction quality compared with the standard CS algorithm. For higher CRs, lower dimensional projections are allowed, meanwhile guaranteeing a correct reconstruction. Thus, low computational high quality data compression/reconstruction are achieved with minimal energy expenditure at the sensors nodes.