Showing papers in "IEEE Transactions on Circuits and Systems I-regular Papers in 2013"
TL;DR: This paper provides a comprehensive and detailed graph-theoretic analysis of Kron reduction encompassing topological, algebraic, spectral, resistive, and sensitivity analyses and leads to novel insights both on the mathematical and the physical side.
Abstract: Consider a weighted undirected graph and its corresponding Laplacian matrix, possibly augmented with additional diagonal elements corresponding to self-loops. The Kron reduction of this graph is again a graph whose Laplacian matrix is obtained by the Schur complement of the original Laplacian matrix with respect to a specified subset of nodes. The Kron reduction process is ubiquitous in classic circuit theory and in related disciplines such as electrical impedance tomography, smart grid monitoring, transient stability assessment, and analysis of power electronics. Kron reduction is also relevant in other physical domains, in computational applications, and in the reduction of Markov chains. Related concepts have also been studied as purely theoretic problems in the literature on linear algebra. In this paper we analyze the Kron reduction process from the viewpoint of algebraic graph theory. Specifically, we provide a comprehensive and detailed graph-theoretic analysis of Kron reduction encompassing topological, algebraic, spectral, resistive, and sensitivity analyses. Throughout our theoretic elaborations we especially emphasize the practical applicability of our results to various problem setups arising in engineering, computation, and linear algebra. Our analysis of Kron reduction leads to novel insights both on the mathematical and the physical side.
715 citations
TL;DR: It is shown that the proposed TEAM, ThrEshold Adaptive Memristor model is reasonably accurate and computationally efficient, and is more appropriate for circuit simulation than previously published models.
Abstract: Memristive devices are novel devices, which can be used in applications ranging from memory and logic to neuromorphic systems. A memristive device offers several advantages: nonvolatility, good scalability, effectively no leakage current, and compatibility with CMOS technology, both electrically and in terms of manufacturing. Several models for memristive devices have been developed and are discussed in this paper. Digital applications such as memory and logic require a model that is highly nonlinear, simple for calculations, and sufficiently accurate. In this paper, a new memristive device model is presented-TEAM, ThrEshold Adaptive Memristor model. This model is flexible and can be fit to any practical memristive device. Previously published models are compared in this paper to the proposed TEAM model. It is shown that the proposed model is reasonably accurate and computationally efficient, and is more appropriate for circuit simulation than previously published models.
666 citations
TL;DR: This paper illustrates that for a device to be a memristor it should exhibit three characteristic fingerprints: 1) When driven by a bipolar periodic signal the device must exhibit a “pinched hysteresis loop” in the voltage-current plane, assuming the response is periodic.
Abstract: This paper illustrates that for a device to be a memristor it should exhibit three characteristic fingerprints: 1) When driven by a bipolar periodic signal the device must exhibit a “pinched hysteresis loop” in the voltage-current plane, assuming the response is periodic. 2) Starting from some critical frequency, the hysteresis lobe area should decrease monotonically as the excitation frequency increases, and 3) the pinched hysteresis loop should shrink to a single-valued function when the frequency tends to infinity. Examples of memristors exhibiting these three fingerprints, along with non-memristors exhibiting only a subset of these fingerprints are also presented. In addition, two different types of pinched hysteresis loops; the transversal (self-crossing) and the non-transversal (tangential) loops exhibited by memristors are also discussed with its identification criterion.
472 citations
TL;DR: It is established that, under the assumptions that each agent is asymptotically null controllable with bounded controls and that the network is connected or jointly connected, semi-global leader-following consensus of the multi-agent system can be achieved.
Abstract: This paper investigates the problem of leader-following consensus of a linear multi-agent system on a switching network. The input of each agent is subject to saturation. Low gain feedback based distributed consensus protocols are developed. It is established that, under the assumptions that each agent is asymptotically null controllable with bounded controls and that the network is connected or jointly connected, semi-global leader-following consensus of the multi-agent system can be achieved. Numerical examples are presented to illustrate this result.
456 citations
TL;DR: The purpose of this paper is to solve the H∞, L2 - L∞ passive and dissipative filtering problems in a unified framework by using a new performance index that is referred to as extended dissipativity, and the effectiveness of the proposed methods is substantiated with three illustrative examples.
Abstract: This paper is concerned with the design of mode-dependent and mode-independent filters for continuous-time linear Markovian jump systems (MJSs) with time-varying delays. Different from the existing studies in the literature, the purpose of this paper is to solve the H∞, L2 - L∞ passive and dissipative filtering problems in a unified framework. This purpose is successfully realized by using a new performance index that is referred to as extended dissipativity. The extended dissipative inequality contains several weighting matrices. By tuning the weighting matrices, the extended dissipativity will reduce to the H∞ performance, L2 - L∞ performance, passivity and dissipativity, respectively. Delay-dependent conditions for the analysis of stochastic stability and extended dissipativity for MJSs with time-varying delays are obtained by using a mode-dependent Lyapunov-Krasovskii functional together with a novel integral inequality. Based on these conditions, the design methods for mode-dependent and mode-independent filters are developed based on linear matrix inequalities. The designed filters guarantee that the resulting filtering error system is stochastically stable and extended dissipative for any admissible delays. Finally, the effectiveness of the proposed methods is substantiated with three illustrative examples.
408 citations
TL;DR: A new wireless power transfer technique using optimal resonant load transformation is presented with significantly improved efficiency at the cost of only one additional chip inductor component, which is suitable for batch production, as well as biocompatible owing to no incorporation of ferromagnetic core.
Abstract: Wireless power transfer provides a safe and robust way for powering biomedical implants, where high efficiency is of great importance A new wireless power transfer technique using optimal resonant load transformation is presented with significantly improved efficiency at the cost of only one additional chip inductor component The optimal resonant load condition for the maximized power transfer efficiency is explained The proposed technique is implemented using printed spiral coils with discrete surface mount components at 1356 MHz power carrier frequency With an implantable coil having an area of 25 mm × 10 mm and a thickness of 05 mm, the power transfer efficiency of 58% is achieved in the tissue environment at 10-mm distance from the external coil Compared to previous works, the power efficiency is much higher and the structure is compact with planar integration, easy to tune, and suitable for batch production, as well as biocompatible owing to no incorporation of ferromagnetic core
276 citations
TL;DR: Continuous measurement can be achieved with an implanted monitor to improve treatment regiments, assess patient compliance to medication schedules, and prevent unnecessary vision loss.
Abstract: Circuit blocks for a 1.5 mm3 microsystem enable continuous monitoring of intraocular pressure. Due to power and form-factor limitations, circuit blocks are designed at nanowatt power levels not completely explored before. The system includes a 75% efficient 90 nW DC-DC converter which is the most efficient reported sub- μW converter in literature. It also includes a novel 4.7 nJ/bit FSK radio that achieves 10 cm of transmission range at 10 -6 BER which is also the lowest number reported for short-range through-tissue wireless links for biomedical implants. A MEMS capacitive sensor and ΣΔ capacitance-to-digital converter measure IOP with 0.5 mmHg accuracy. A microcontroller processes and saves IOP data and stores it in a 2.4 fW/bitcell SRAM. The microsystem harvests a maximum power of 80 nW in sunlight with a light irradiance of 100 mW/cm2 AM 1.5 from an integrated 0.07 mm2 solar cell to recharge a 1 mm2 1 μAh thin-film battery and power the load circuits. The design achieves zero-net-energy operation with 1.5 hours of sunlight or 10 hours of bright indoor lighting daily.
272 citations
TL;DR: This paper presents the design of a cost effective, hybrid energy harvesting circuit combining a solar cell and a rectenna capable to harvest ambient electromagnetic energy.
Abstract: This paper presents the design of a cost effective, hybrid energy harvesting circuit combining a solar cell and a rectenna capable to harvest ambient electromagnetic energy. Electromagnetic analysis is used to model and optimize the designed circuits in order to allow the antenna and solar cell to share the same area leading to a compact structure. Nonlinear harmonic balance optimization is used to maximize the RF-to-DC conversion efficiency of the rectenna circuitry in the presence of the solar cell and both wideband and multiband topologies are presented. Furthermore, a low cost and flexible polyethylene terephthalate PET substrate and a flexible amorphous silicon solar cell are chosen, providing for both a low cost and conformal structure. A prototype able to generate a maximum DC power of 56 mW when the solar cell is illuminated with 100 mW/cm2 solar irradiance, and a dual band rectenna demonstrating an efficiency of 15% around 850 MHz and 1850 MHz when illuminated by a microwave signal of available power is presented.
211 citations
TL;DR: By designing a novel Lyapunov functional, using some inequalities and the properties of random variables, several delay-dependent synchronization criteria are derived for the coupled networks of continuous-time version and its discrete-time analogues.
Abstract: This paper studies synchronization in an array of coupled neural networks with Markovian jumping and random coupling strength. The array of neural networks are coupled in a random fashion which is governed by Bernoulli random variable and each node has an interval time-varying delay. By designing a novel Lyapunov functional, using some inequalities and the properties of random variables, several delay-dependent synchronization criteria are derived for the coupled networks of continuous-time version. Discrete-time analogues of the continuous-time networks are also formulated and studied. Some new lemmas are developed to obtain less conservative synchronization criteria of both continuous-time model and its discrete-time analogues. Numerical examples of both continuous-time system and its discrete-time analogues are finally given to demonstrate the effectiveness of the theoretical results.
188 citations
TL;DR: The relationship between frequency bifurcation and splitting is elucidated; and a zero-phase control method is suggested to track the splitting frequency when the coupling changes in the splitting region.
Abstract: Frequency splitting phenomena are investigated systematically by circuit theory in a series-tuned contactless power transfer (CPT) system. First, in a symmetrical CPT system, the splitting equation is defined and the key frequency splitting characteristics are described by the trough and the ridge equations in a complete fashion. The even and the odd splitting frequencies are exactly two roots of the ridge equation; the splitting coupling is determined theoretically when the even and odd splitting frequencies merge together. Second, in an unsymmetrical CPT system, the idea of the trough and the ridge equation is exploited to find exactly the splitting coupling. Next, the relationship between frequency bifurcation and splitting is elucidated; and a zero-phase control method is suggested to track the splitting frequency when the coupling changes in the splitting region. Finally, the theoretical results are validated by a 10-W prototype with planar spiral coils.
173 citations
TL;DR: To eliminate the chattering phenomenon occurred in non-Lipschitz dynamical systems, this paper introduces a saturation function to replace the original sign function in the proposed distributed tracking protocols.
Abstract: This paper aims at further investigating the finite-time distributed tracking control problems for multi-agent systems with a virtual leader under the conditions of fixed and switching topologies, respectively. Two continuous distributed tracking protocols are designed for tracking the virtual leader in finite time. Compared with the traditional distributed tracking protocols, the proposed distributed tracking protocols can reach consensus in finite time. In particular, to eliminate the chattering phenomenon occurred in non-Lipschitz dynamical systems, this paper introduces a saturation function to replace the original sign function in the proposed distributed tracking protocols. The improved protocols can guide all agents to track the virtual leader without chattering phenomenon in finite time for the same position. Numerical simulations are also given to validate the proposed distributed tracking protocols.
TL;DR: A time-to-digital converter architecture capable of reaching high-precision and high-linearity with moderate area occupation per measurement channel with a couple of two-stage interpolators that exploit the cyclic sliding scale technique in order to improve the conversion linearity.
Abstract: This paper presents a time-to-digital converter (TDC) architecture capable of reaching high-precision and high-linearity with moderate area occupation per measurement channel. The architecture is based on a coarse counter and a couple of two-stage interpolators that exploit the cyclic sliding scale technique in order to improve the conversion linearity. The interpolators are based on a new coarse-fine synchronization circuit and a new single-stage Vernier delay loop fine interpolation. In a standard cost-effective 0.35 μm CMOS technology the TDC reaches a dynamic range of 160 ns, 17.2 ps precision and differential non-linearity better than 0.9% LSB rms. The TDC building block was designed in order to be easily assembled in a multi-channel monolithic TDC chip. Coupled with a SPAD photodetector it is aimed for TCSPC applications (like FLIM, FCS, FRET) and direct ToF 3-D ranging.
TL;DR: This paper aims to further investigate the flocking and preserving connectedness in multi-agent nonholonomic systems with proximity graphs, in which the positions and the relative distances are not available to the distributed controllers.
Abstract: Multi-agent systems are ubiquitous in the real-world and have received an increasing attention by many researchers worldwide. A multi-agent system is composed of many agents interconnected by a communication network. This paper aims to further investigate the flocking and preserving connectedness in multi-agent nonholonomic systems with proximity graphs, in which the positions and the relative distances are not available to the distributed controllers. Several sufficient conditions are derived to resolve the above problem based on the kinematic model and the dynamic model, respectively. These sufficient conditions indicate that, for any given distinct initial positions and connected initial graph, there always exist gains of the linear protocols to preserve the connectedness of the graph and realize flocking. Moreover, under an additional condition on initial heading angles, the similar result is obtained for a nonlinear protocol with the form of Kuramoto model. Finally, numerical simulations are given to validate the above theoretical results.
TL;DR: A fast and unconditionally stable maximum power point tracking scheme with high tracking efficiency and all range stability is proposed for photovoltaic generators and a typical convergence time of 15 ms is shown.
Abstract: A fast and unconditionally stable maximum power point tracking scheme with high tracking efficiency is proposed for photovoltaic generators. The fast dynamics and all range stability are attained by a sliding mode control and the high tracking efficiency by a maximum power point algorithm with fine step. In response to a sudden change in radiation, our experiments show a typical convergence time of 15 ms. This is the fastest convergence time reported to date. In addition we demonstrate stable convergence all across the photovoltaic curve, from short-circuit to open-circuit. The theory is validated experimentally.
TL;DR: The existence of a global solution to the resulting system is firstly proved in the Filippov sense and then it is proved that the solution converges to a practical consensus set asymptotically.
Abstract: In this paper, we study the consensus problem of multi-agent networks subject to communication constrains. Undirected and weighted network is considered here. Two types of communication constrains are discussed in this paper: i) each agent can only exchange quantized data with its neighbors and ii) each agent can only obtain the delayed information from its neighbors. The main contribution of this paper is to provide a precise mathematical treatment for the continuous multi-agent network with quantization and time delay. The existence of a global solution to the resulting system is firstly proved in the Filippov sense and then we prove that the solution converges to a practical consensus set asymptotically. Here, practical consensus means that the final consensus values are bounded within an interval, but not a value. Further, an explicit relationship among time delay, quantization parameter and the practical consensus set are theoretically presented. Numerical examples are finally given to demonstrate the effectiveness of the obtained theoretical results.
TL;DR: An operational amplifier is implemented with the proposed input stages and biasing circuits as its core building blocks and including a modified low-voltage class AB output amplifier to guarantee rail-to-rail output voltage range.
Abstract: This paper presents two low-voltage bulk-driven amplifier input stages with enhanced transconductance. The idea is to introduce auxiliary differential pairs into a conventional bulk-driven stage to boost its transconductance. A low-voltage cascode biasing circuitry based on EKV models is also employed to ensure proper operation of the proposed input stages. An operational amplifier is then implemented with the proposed input stages and biasing circuits as its core building blocks and including a modified low-voltage class AB output amplifier to guarantee rail-to-rail output voltage range. The overall amplifier was implemented in a 0.35 μm n-well CMOS process using 1-V power supply. The measurement results show significant improvement in the performance of the operational amplifier compared to prior arts.
TL;DR: A dual sample-and-hold architecture is proposed, which extends the sampling time of the ADC and reduces the average power per channel by more than 50% compared to the conventional multiplexing neural recording system.
Abstract: This paper presents a fully implantable 100-channel neural interface IC for neural activity monitoring. It contains 100-channel analog recording front-ends, 10 multiplexing successive approximation register ADCs, digital control modules and power management circuits. A dual sample-and-hold architecture is proposed, which extends the sampling time of the ADC and reduces the average power per channel by more than 50% compared to the conventional multiplexing neural recording system. A neural amplifier (NA) with current-reuse technique and weak inversion operation is demonstrated, consuming 800 nA under 1-V supply while achieving an input-referred noise of 4.0 μVrms in a 8-kHz bandwidth and a NEF of 1.9 for the whole analog recording chain. The measured frequency response of the analog front-end has a high-pass cutoff frequency from sub-1 Hz to 248 Hz and a low-pass cutoff frequency from 432 Hz to 5.1 kHz, which can be configured to record neural spikes and local field potentials simultaneously or separately. The whole system was fabricated in a 0.18-μm standard CMOS process and operates under 1 V for analog blocks and ADC, and 1.8 V for digital modules. The number of active recording channels is programmable and the digital output data rate changes accordingly, leading to high system power efficiency. The overall 100-channel interface IC consumes 1.16-mW total power, making it the optimum solution for multi-channel neural recording systems.
TL;DR: An ultra-low quiescent current output-capacitorless low-dropout (OCL-LDO) regulator with adaptive power transistors technique is presented, which shows a significant improvement in term of OCL- LDO transient figure-of-merit (FOM) as well as balanced performance parameters in terms of PSR, line regulation and load regulation.
Abstract: An ultra-low quiescent current output-capacitorless low-dropout (OCL-LDO) regulator with adaptive power transistors technique is presented in this paper. The proposed technique permits the regulator to transform itself between 2-stage and 3-stage cascaded topologies with respective power transistor, depending on the load current condition. As such, it enables the OCL-LDO regulator to achieve ultra-low power consumption, high stability and good transient response without the need of off-chip capacitor at the output. The proposed LDO regulator has been implemented and fabricated in a UMC 65-nm CMOS process. It occupies an active area of 0.017 mm2 . The measured results have shown that the proposed circuit consumes a quiescent current of 0.9 μA at no load, regulating the output at 1 V from a voltage supply of 1.2 V. It achieves full range stability from 0 to 100 mA load current at a maximum 100 pF parasitic capacitance load. The measured transient output voltage is 68.8 mV when load current is stepped from 0 to 100 mA in 300 ns with CL = 100 pF. The recovery time is about 6 μs. Compared to previously reported counterparts, the proposed OCL-LDO regulator shows a significant improvement in term of OCL-LDO transient figure-of-merit (FOM) as well as balanced performance parameters in terms of PSR, line regulation and load regulation.
TL;DR: It is demonstrated that it is difficult to harvest RF energy over a wide frequency band if the ambient RF energy sources are weak, owing to the voltage requirements.
Abstract: RF energy is widely available in urban areas and thus presents a promising ambient energy harvesting source. In this paper, a CMOS harvester circuit is modeled and analyzed in detail at low environmental power levels. Based on the circuit analysis, a design procedure is given for a narrowband energy harvester. The antenna and harvester co-design methodology is discussed to improve RF to DC energy conversion efficiency. We demonstrate that it is difficult to harvest RF energy over a wide frequency band if the ambient RF energy sources are weak, owing to the voltage requirements. Since most ambient RF energy lies in a few narrow bands, a dual/multi-band energy harvester architecture should be able to harvest much of the available RF energy. A dual-band CMOS energy harvester is designed and fabricated using an IBM 0.13 μm process. The simulated and measured results demonstrate a dual-band energy harvester that obtains over 9% efficiency for two different bands (around 900 MHz and around 1900 MHz) at an input power as low as -19.3 dBm. The DC output voltage of this harvester is over 1 V, which can be used to recharge the battery to form an inexhaustibly powered communication system.
TL;DR: This paper investigates drive-response synchronization of a class of neural networks with time-varying delays and discontinuous activations and designs Discontinuous state feedback controller and adaptive controller such that the considered model can realize exponential complete synchronization.
Abstract: This paper investigates drive-response synchronization of a class of neural networks with time-varying delays and discontinuous activations. Discontinuous state feedback controller and adaptive controller are designed such that the considered model can realize exponential complete synchronization. Moreover, the convergence rate is explicitly estimated when state feedback control is utilized. The obtained results are also applicable to neural networks with continuous activations since they are a special case of neural networks with discontinuous activations. Results of this paper improve corresponding ones which only quasi-synchronization can be achieved for neural networks with discontinuous activations. Finally, numerical simulations are given to verify the effectiveness of the theoretical results.
TL;DR: It is found that consensus and quasi-consensus in a multi-agent system cannot be reached without the delayed position information under the given protocol while they can be achieved with a relatively small time delay by appropriately choosing the coupling strengths.
Abstract: This paper studies consensus and quasi-consensus in multi-agent dynamical systems. A linear consensus protocol in the second-order dynamics is designed where both the current and delayed position information is utilized. Time delay, in a common perspective, can induce periodic oscillations or even chaos in dynamical systems. However, it is found in this paper that consensus and quasi-consensus in a multi-agent system cannot be reached without the delayed position information under the given protocol while they can be achieved with a relatively small time delay by appropriately choosing the coupling strengths. A necessary and sufficient condition for reaching consensus in multi-agent dynamical systems is established. It is shown that consensus and quasi-consensus can be achieved if and only if the time delay is bounded by some critical value which depends on the coupling strength and the largest eigenvalue of the Laplacian matrix of the network. The motivation for studying quasi-consensus is provided where the potential relationship between the second-order multi-agent system with delayed positive feedback and the first-order system with distributed-delay control input is discussed. Finally, simulation examples are given to illustrate the theoretical analysis.
TL;DR: This paper proves that under some assumptions, the second-order consensus can be reached exponentially, but also gives an analytical estimation of the upper bounds of convergence rate and the switching rate.
Abstract: This paper discusses the second-order local consensus problem for multi-agent systems with nonlinear dynamics over dynamically switching random directed networks. By applying the orthogonal decomposition method, the state vector of resulted error dynamical system can be decomposed as two transversal components, one of which evolves along the consensus manifold and the other evolves transversally with the consensus manifold. Several sufficient conditions for reaching almost surely second-order local consensus are derived for the cases of time-delay-free coupling and time-delay coupling, respectively. For the case of time-delay-free coupling, we find that if there exists one directed spanning tree in the network which corresponds to the fixed time-averaged topology and the switching rate of the dynamic network is not more than a critical value which is also estimated analytically, then second-order dynamical consensus can be guaranteed for the choice of suitable parameters. For the case of time-delay coupling, we not only prove that under some assumptions, the second-order consensus can be reached exponentially, but also give an analytical estimation of the upper bounds of convergence rate and the switching rate. Finally, numerical simulations are provided to illustrate the feasibility and effectiveness of the obtained theoretical results.
TL;DR: A novel time-domain bulk-tuned offset cancellation technique is applied to a low-power high-precision dynamic comparator to reduce its input-referred offset with minimal additional power consumption and delay.
Abstract: A novel time-domain bulk-tuned offset cancellation technique is applied to a low-power high-precision dynamic comparator to reduce its input-referred offset with minimal additional power consumption and delay. The design has been fabricated in a commercially available 0.5-μm process. Measurement results of 10 circuits show a reduction of offset standard deviation from 5.415 mV to 50.57 μV, improved by a factor of 107.1. The offset cancellation scheme does not introduce observable offset or noise, and can achieve fast and robust convergence with a wide range of common mode input. Operating at a supply of 5 V and clock frequency of 200 kHz, the comparator together with the OC circuitry consumes 4.65 μW of power, or 23 pJ of energy per comparison.
TL;DR: A new digital background calibration technique for gain mismatches and sample-time mismatches in a Time-Interleaved Analog-to-Digital Converter (TI-ADC) is presented to reduce the circuit area.
Abstract: A new digital background calibration technique for gain mismatches and sample-time mismatches in a Time-Interleaved Analog-to-Digital Converter (TI-ADC) is presented to reduce the circuit area. In the proposed technique, the gain mismatches and the sample-time mismatches are calibrated by using pseudo aliasing signals instead of using a bank of adaptive FIR filters which is conventionally utilized. The pseudo aliasing signals are generated and subtracted from an ADC output. A pseudo aliasing generator consists of the Hadamard transform and a fixed FIR filter. In case of a two-channel 10-bit TI-ADC, the proposed technique reduces the requirement for a word length of the FIR filter by about 50% without a look-up table (LUT) compared with the conventional technique. In addition, the proposed technique requires only one FIR filter compared with the bank of adaptive filters which requires (M-1) FIR filters in an M-channel TI-ADC.
TL;DR: This is the first integrated 77-GHz automotive radar transceiver with the feature of anti-interference, and the proposed frequency-hopping random chirp FMCW technique reconfigures the chirP sweep frequency and time every cycle to result in noise-like frequency response for mutual interference after the received signal is down-converted and demodulated.
Abstract: This paper presents a 77-GHz long-range automotive radar transceiver with the function of reducing mutual interference. The proposed frequency-hopping random chirp FMCW technique reconfigures the chirp sweep frequency and time every cycle to result in noise-like frequency response for mutual interference after the received signal is down-converted and demodulated. Thus, the false alarm rate can be reduced significantly. The transceiver IC is fully integrated in TSMC 1P9M 65-nm digital CMOS technology. The chip including pads occupies a silicon area of 1.03 mm × 0.94 mm. The transceiver consumes totally 275 mW of power, and the measured transmitting power and receiver noise figure are 6.4 dBm and 14.8 dB, respectively. To the authors' knowledge, this is the first integrated 77-GHz automotive radar transceiver with the feature of anti-interference.
TL;DR: The proposed analysis can be used to model charge migration in amorphous materials, which may be associated to specific macroscopic or microscopic scale fractal geometrical structures in composites displaying a viscoelastic electromechanical response, as well as to model the collective responses of processes governed by random events described using statistical mechanics.
Abstract: An incidence matrix analysis is used to model a three-dimensional network consisting of resistive and capacitive elements distributed across several interconnected layers. A systematic methodology for deriving a descriptor representation of the network with random allocation of the resistors and capacitors is proposed. Using a transformation of the descriptor representation into standard state-space form, amplitude and phase admittance responses of three-dimensional random RC networks are obtained. Such networks display an emergent behavior with a characteristic Jonscher-like response over a wide range of frequencies. A model approximation study of these networks is performed to infer the admittance response using integral and fractional order models. It was found that a fractional order model with only seven parameters can accurately describe the responses of networks composed of more than 70 nodes and 200 branches with 100 resistors and 100 capacitors. The proposed analysis can be used to model charge migration in amorphous materials, which may be associated to specific macroscopic or microscopic scale fractal geometrical structures in composites displaying a viscoelastic electromechanical response, as well as to model the collective responses of processes governed by random events described using statistical mechanics.
TL;DR: This work extends the prior work by utilizing an additional 0.5-bit raw SAR code to eliminate the missing code, and by employing a temporal averaging with a FIR LPF to measure the error code reliably in spite of the supply noise.
Abstract: A digital-domain calibration method is proposed for a split-capacitor DAC (split-CDAC) used in a differential-type 11-bit SAR ADC. It calibrates the nonlinearities of SAR ADC due to the DAC capacitance mismatch as well as the two parasitic capacitances connected in parallel with each of the bridge capacitor and the LSB bank of split-CDAC. The proposed ADC does not require any additional analog circuits for calibration, because it utilizes one of the two split-CDACs to measure the error codes of the other split-CDAC. During the normal A/D conversion step, the 11.5-bit raw SAR code output of ADC is added to the pre-measured error codes to generate the 11-bit calibrated output code. The analog block of the ADC was fabricated in a 0.13- μm CMOS process, and the digital block was implemented in a FPGA. The measured SNDR and SFDR are 61.6 dB (ENOB 9.93 bits) and 78 dB at the Nyquist rate with a 5 kHz sine wave input. INL and DNL are measured to be +0.96/-0.98 LSB, and +0.96/-0.97 LSB, respectively. This work extends the prior work by utilizing an additional 0.5-bit raw SAR code to eliminate the missing code, and by employing a temporal averaging with a FIR LPF to measure the error code reliably in spite of the supply noise.
TL;DR: Stochastic synchronization is studied for complex networks with delayed coupling and mixed impulses by using the average impulsive interval approach and the comparison principle to guarantee that exponential synchronization of complex networks is achieved in the mean square.
Abstract: In this paper, stochastic synchronization is studied for complex networks with delayed coupling and mixed impulses Mixed impulses are composed of desynchronizing and synchronizing impulses The delayed coupling term involves transmission delay and self-feedback delay By using the average impulsive interval approach and the comparison principle, several conditions are derived to guarantee that exponential synchronization of complex networks is achieved in the mean square The derived conditions are closely related to the impulsive strengths, the frequency of impulse occurrence, and the coupling structure of complex networks Numerical simulations are presented to further demonstrate the effectiveness of the proposed approach
TL;DR: A systematic method for developing a binary version of a given transform by using the Walsh-Hadamard transform (WHT) is proposed and it is shown that the resulting BDCT corresponds to the well-known sequency-ordered WHT, whereas the BDHT can be considered as a new Hartley-ordering WHT.
Abstract: In this paper, a systematic method for developing a binary version of a given transform by using the Walsh-Hadamard transform (WHT) is proposed. The resulting transform approximates the underlying transform very well, while maintaining all the advantages and properties of WHT. The method is successfully applied for developing a binary discrete cosine transform (BDCT) and a binary discrete Hartley transform (BDHT). It is shown that the resulting BDCT corresponds to the well-known sequency-ordered WHT, whereas the BDHT can be considered as a new Hartley-ordered WHT. Specifically, the properties of the proposed Hartley-ordering are discussed and a shift-copy scheme is proposed for a simple and direct generation of the Hartley-ordering functions. For software and hardware implementation purposes, a unified structure for the computation of the WHT, BDCT, and BDHT is proposed by establishing an elegant relationship between the three transform matrices. In addition, a spiral-ordering is proposed to graphically obtain the BDHT from the BDCT and vice versa. The application of these binary transforms in image compression, encryption and spectral analysis clearly shows the ability of the BDCT (BDHT) in approximating the DCT (DHT) very well.
TL;DR: A multi-access multiple-input multiple-output relay differential chaos shift keying cooperative diversity system is proposed in this paper as a comprehensive cooperation scheme, in which the relay and destination both employ multiple antennas to strengthen the robustness against signal fading in a wireless network.
Abstract: A multi-access multiple-input multiple-output (MIMO) relay differential chaos shift keying cooperative diversity (DCSK-CD) system is proposed in this paper as a comprehensive cooperation scheme, in which the relay and destination both employ multiple antennas to strengthen the robustness against signal fading in a wireless network. It is shown that, with spatial diversity gains, the bit error rate (BER) performance of the proposed system is remarkably better than the conventional DCSK non-cooperation (DCSK-NC) and DCSK cooperative communication (DCSK-CC) systems. Moreover, the exact BER and close-form expressions of the proposed system are derived over Nakagami fading channels through the moment generating function (MGF), which is shown to be highly consistent with the simulation results. Meanwhile, this paper illustrates a trade-off between the performance and the complexity, and provides a threshold for the number of relay antennas keeping the user consumed energy constant. Due to the above-mentioned advantages, the proposed system stands out as a good candidate or alternative for energy-constrained wireless communications based on chaotic modulation, especially for low-power and low-cost wireless personal area networks (WPANs).