Optimization of Linear Phase FIR Filters in Dynamically Expanding Subexpression Space

The most advanced techniques in the design of multiplierless finite impulse response (FIR) filters explore common subexpression sharing when the filter coefficients are optimized. Existing techniques, however, either suffer from a heavy computational overhead, or have no guarantees on the minimal hardware cost in terms of the number of adders. A recent technique capable of designing long filters optimizes filter coefficients in pre-specified subexpression spaces. The pre-specified subexpression spaces determine if a filter with fewer adders may be achieved. Unfortunately, there is no known technique that can find subexpression spaces that can guarantee the solution with the minimum number of adders in the implementation. In this paper, a tree search algorithm is proposed to update and expand the subexpression spaces dynamically, and thus, to achieve the maximum subexpression sharing during the optimization. Numerical examples show that the proposed algorithm generates filters using fewer adders than other non-optimum algorithms. On the other hand, as a consequence of its efficiency, our proposed technique is able to design longer filters than the global optimum algorithm.     

Programmable Switched Capacitor Finite Impulse Response Filter with Circular Memory Implemented in CMOS 0.18 μm Technology

This paper presents a programmable multi-mode finite impulse response (FIR) filter implemented as switched capacitor (SC) technique in CMOS 0.18 μm technology. Intended application of the described circuit is in analog base-band filtering in GSM/WCDMA systems. The proposed filter features a regular structure that allows for elimination of some parasitic capacitances, thus significantly improving the filtering accuracy. Due to its modularity that allows for dividing the circuit into two separate sections, the circuit can be easily reconfigured to work as either infinite impulse response (IIR) or as finite impulse (FIR) filter. One of the key components that allows for this multi-mode operation is the proposed programmable and ultra low power multiphase clock circuit. The 24-taps filter for the sampling frequency of 30 MHz dissipates power of 4.5 mW from a 1.8 V supply.     

Estimation of the Non-Measurable State Variables of a Transcutaneous Energy Transmission System for Artificial Human Implants Using Extended Kalman Filters

Due to the separation of the two sides of the coupling network, the acquisition of data on the operating state variables of a transcutaneous energy transmission system (TETS) inside the human body is difficult. A non-measurable state estimation approach is used in this work to facilitate the estimation of non-measurable variables on the secondary side of the TETS, including the current of the secondary coil and the output voltage of the secondary side. The estimation algorithm is based on a discrete dynamic mathematical model of the TETS. Following this model, using the extended Kalman filter (EKF) algorithm, the complexity of the TETS for artificial human implants can be reduced, while the reliability is simultaneously enhanced. Additionally, as an adaptive filter, the EKF can also successfully filter out processing noise during energy transmission. All of the results are verified by simulation using MATLAB.     

A Novel Diversity-Controlled Genetic Algorithm for Rapid Optimization of Bandpass FRM FIR Digital Filters Over CSD Multiplier Coefficient Space

The conventional frequency response masking (FRM) approach is one of the most well-known techniques for the design of sharp transition band finite impulse response (FIR) digital filters. The resulting FRM digital filters permit efficient hardware implementations due to an inherently large number of zero-valued multiplier coefficients. The hardware complexity of these digital filters can further be reduced by representing the remaining (non-zero) multiplier coefficient values by using their canonical signed-digit (CSD) representations. This paper presents a novel diversity-controlled (DC) genetic algorithm (GA) for the discrete optimization of bandpass FRM FIR digital filters over the CSD multiplier coefficient space. The resulting bandpass FIR digital filters are permitted to have equal or unequal lower and upper transition bandwidths. The proposed DCGA is based on an indexed look-up table of permissible CSD multiplier coefficients such that their indices form a closed set under the genetic operations of crossover and mutation. The salient advantage of DCGA over the conventional GA lies in the external control over population diversity and parent selection, giving rise to a rapid convergence to an optimal solution. The external control is achieved through the judicious choice of a pair of DCGA optimization parameters. An empirical investigation is undertaken for choosing appropriate values for these control parameters. The convergence speed advantages of the DCGA are demonstrated through its application to the design and optimization of a pair of bandpass FRM FIR digital filters with equal or arbitrary lower and upper transition bandwidths. In both cases, an increase of about an order of magnitude in the speed of convergence is achieved as compared to the conventional GAs.     

Design and Implementation of a Cueing Wideband Digital EW Receiver

A cueing wideband digital Electronic Warfare （EW） receiver is presented. The proposed receiver, which is to measure the instantaneous frequency and bandwidth of the intercept short-duration pulse radar signals that cue and match the corresponding ones, meets the requirements of good sensitivity and dynamic range for EW and can save hardware resources greatly as well. In addition, real-time signal processing, which is the main bottleneck for covering a wide instantaneous frequency band for EW receiver, is better solved in the proposed design structure. The highly efficient implementation and good parameter estimation algorithms are proposed as welL Theoretical analysis and experimental results show that this structure is feasible.     

Design of Unequal Thickness Interference Filters with Quarter Wavelength Stack

A system of unequal thickness interference filters with quarter wavelength stack which consists of a spacer surrounded by two multiplayer stacks is designed, and the examples of the filter design are given.This kind of filters are not only characterized by high-transparency, but also by high-reflection, therefore, it is superior to the common equal thickness interference system with quarter wavelength.it is easier to control the manufacturing techniques of the new design as compared with that of interference filter of non-quarter wavelength.     

A Swept-Frequency Wideband Channel Sounding System at the 63.4–64.4 GHz Band with 1 ns Time-Resolution

A Versatile channel sounding impulse response identification system using the swept-frequency method is designed at the 63.4–64.4 GHz band. The swept-frequency channel sounder offers high time and frequency resolution of 1 ns and 625 KHz respectively. The high dynamic range (70 dB) and constant power enable non-linearities to be overcome in the measurement areas lying with the coverage range of the order of a picocell.     

A Canonical Voltage-Controlled VM-APS with a Grounded Capacitor

A new canonical first order voltage-mode all-pass section (VM-APS) employing a single grounded capacitor as the only passive element and two differential voltage current conveyors as the active elements is proposed. The circuit, with its attractive features of resistorless realization, voltage-controlled pole frequency and low impedance voltage output is a novel and unique offering to the field and an addition to the rich literature on the subject. PSPICE simulations are carried out in 0.5 μ CMOS technology to validate the utility of the proposed circuit.     

A Very Efficient Approach for the Synthesis of 2-D Recursive Fan Filters

ＡＶｅｒｙＥｆｆｉｃｉｅｎｔＡｐｐｒｏａｃｈｆｏｒｔｈｅＳｙｎｔｈｅｓｉｓｏｆ２－ＤＲｅｃｕｒｓｉｖｅＦａｎＦｉｌｔｅｒｓＺｈｕＷｅｉｐｉｎｇ（ＤｅｐａｒｔｍｅｎｔｏｆＴｅｌｅｃｏｍｍｕｎｉｃａｔｉｏｎＥｎｇｉｎｅｅｒｉｎｇ，ＮａｎｊｉｎｇＵｎｉｖｅ...     

Wideband Direction of Arrival Estimation with Linear Array： Analysis and Closed-Form Formulae

To estimate the Direction-of-arrival （DOA） of a far-field wideband source using a linear array, the Time-difference-of-arrlval （TDOA） based and Steered- response power （SRP） algorithms are of the most useful. In this paper, for white Gaussian signal and noise, the esti- mation variances of both the methods and the Cramer-Rao lower bound （CRLB） are derived in closed-form for a lin- ear array. Meanwhile, a Gauss-Markov （GM） procedure is introduced to achieve optimal conversion of the estimated delay vectors for the TDOA based estimator. Moreover, a generalized SRP estimator is proposed for the generalized case with nonuniform SNR.     

The Experiment of A 220 GHZ Gyrotron with a Pulse Magnet

A 220 GHz gyrotron with an 8 T pulse magnet has been designed, constructed and operated in Terahertz Research Center, University of Electronic Science and Technology of China. TE₀₃ mode is selected as the operation mode, which is less susceptible to the mode competition. Experimental results show the output power is achieved 11.5 kW with efficiencies of 12.8%, and the frequency is between 219.6 GHz and 234.2 GHz.     

Design of a Compact Hexagonal Monopole Antenna for Ultra—Wideband Applications

This paper presents two design compact hexagonal monopole antennas for ultra-wideband applications. The two antennas are fed by a single microstrip line . The Zeland IE3D version 12 is employed for analysis at the frequency band of 4 to 14 GHz which has approved as a commercial UWB band. The experimental and simulation results exhibit good agreement together for antenna 1. The proposed antenna1 is able to achieve an impedance bandwidth about 111%. The proposed antenna2 is able to achieve an impedance bandwidth about (31.58%) for lower frequency and (62.54%) for upper frequency bandwidth. A simulated frequency notched band ranging from 6.05 GHz to 7.33 GHz and a measured frequency notched band ranging from 6.22 GHz to 8.99 GHz are achieved and gives one narrow band of axial ratio (1.43%). The proposed antennas can be used in wireless ultra-wideband (UWB) communications.     

Design of 50–70 GHz Planar Wideband Bandpass Filter on Liquid Crystal Polymer Substrate

In this paper, the authors propose a novel and compact 50-70 GHz planar microstrip bandpass filter, possessing sharp-rejection, low insertion-loss and wide-band characteristics, based on Liquid Crystal Polymer (LCP) substrates. The filter is fabricated on LCP substrates by using standard processing technologies. The proposed filter exhibits a return loss level better than 10 dB, an insertion loss of 5 dB and a 3-dB bandwidth of 30%.The measured and simulated results show good agreement, proving that LCPs are potential and very promising materials for flexible millimeter-wave substrate applications.     

Design of a 300 GHz Band TWT with a Folded Waveguide Fabricated by Microelectromechanical Systems

For future broadband wireless links, we have designed a 300 GHz band traveling wave tube (TWT) with a folded waveguide fabricated by microelectromechanical systems (MEMS). The TWT operates at a beam voltage of 12 kV and a beam current of 8.3 mA. The classical large signal simulation code predicts the output power greater than 1 W and gain larger than 20 dB over the bandwidth from 280 to 300 GHz.     

Bit-per-joule performance of power saving ad hoc networks with a mobile backbone

Energy efficient MAC protocols have been developed for wireless sensor and mobile ad hoc networks so that inactive nodes can transition into sleep state to conserve energy. It has been recognized that maintaining a continuously awake connected dominating set (CDS) serves to reduce the route setup latency. Under the mobile backbone network (MBN) architecture introduced by Rubin et al., a mobile backbone (Bnet) is dynamically constructed to provide a topological covering of the network. The MBN employs a hybrid routing algorithm under which flows that travel a distance longer than a threshold are directed along routes across the Bnet. In turn, a limited span network-wide global route discovery process is applied for routing shorter distance flows. In this paper, we introduce and analyze an MBN based power saving protocol (MBN-PS) that employs this hybrid routing scheme. Under the MBN-PS scheme, dynamically elected backbone nodes are kept awake, while inactive non-backbone nodes can reside in sleep state. We analytically show that, when the number of network flows is above a minimal level, the throughput per watt efficiency attained in an ad hoc network under complete backbone coverage is better than that achieved by a corresponding network that does not form a backbone. We present a model for the calculation of the bit-per-joule performance of the network as a function of the distance threshold. We confirm the validity of our analytical approach through simulations. Using our method, a network designer is able to choose the optimal distance threshold to be used by this scheme, based on traffic loading conditions.     

Improved H ∞ Filtering for Systems with a Time-Varying Delay

This paper focuses on H _∞ filter design for systems with time-varying delay. A delay-dependent H _∞ performance analysis result is first established for error systems without ignoring any terms in the derivative of the Lyapunov functional by considering the relationship between the time-varying delay and its upper bound. Based on the derived H _∞ performance analysis result, the H _∞ filter is designed in terms of linear matrix inequalities (LMIs). The resulting criteria are extended to systems with polytopic-type uncertainties. Numerical examples are given to demonstrate the merits of the proposed method.     

Design of a 1.1 GSps 12 bit digital to analog convertor with 56 dBc SFDR at Nyquist frequency

High speed digital to analog convertor (DAC) is a key component in software defined radio systems, digital radars and wide band arbitrary waveform generators. In those applications, the performance of the DAC, especially the wideband dynamic range, is important in determining the system performance. In this paper we present a high speed 12 bit current steering DAC with optimized wideband performance. Theoretical analysis and optimizing strategy are present in this paper along with circuit details and measurement results. Experimental results reveal the proposed circuit is capable to operate up to 1.1 GSps. The measured spurious free dynamic range (SFDR) at low frequency is above 70 dBc at 1.1 GHz of sample rate. The SFDR is better than 56 dBc from DC to Nyquist frequency.     

Proportional Plus Integral Control for Set-Point Regulation of a Class of Nonlinear RLC Circuits

In this paper we identify graph-theoretic conditions which allow us to write a nonlinear RLC circuit as port-Hamiltonian with constant input matrices. We show that under additional monotonicity conditions on the network’s components, the circuit enjoys the property of relative passivity, an extended notion of classical passivity. The property of relative passivity is then used to build simple, yet robust and globally stable, proportional plus integral controllers. This work was partially supported by CONACyT, México.     

Novel Design of a High-gain and Wideband Fabry-Pérot Cavity Antenna Using a Tapered AMC Substrate

A high-gain and wideband electromagnetic bandgap (EBG) resonator antenna with a tapered artificial magnetic conductor (AMC) ground plane is presented. The proposed EBG resonator antenna is comprised of a frequency selective surface (FSS) superstrate with a strip dipole array and an AMC ground plane with tapered rectangular patches. The realized gain and the bandwidth of the antenna can be improved simultaneously by using the tapered AMC where the phase difference of the reflected waves from the patches with different length is within 180° and the destructive interference among them can be considerably reduced. The maximum gain is increased about 2∼3 dB and the bandwidth is improved about 2.5 times compared to when the uniform AMC is used.