Design of multibit noise-shaping data converters

A synthesis methodology for selecting locations of thez-domain poles for noise-shaping coders that use multibit internal converters is presented. A key aspect of the proposed methodology is the use of the |L|₁ norm of the noise transfer function to guarantee stability rather than the power gain or |L|₂ norm which is commonly used in the design of 1-bit noise-shaping coders. Simulation verifies that the performance predicted by the new method is within a few dBs of the actual performance. In addition, two hand-designed loop filters from the literature are compared with designs generated by the proposed method.     

Non-fragile <Emphasis Type="Italic">H</Emphasis><Subscript>2</Subscript> and <Emphasis Type="Italic">H</Emphasis><Subscript>∞</Subscript> filter designs for polytopic two-dimensional systems in Roesser model

This paper is concerned with the problem of non-fragile H ₂ and H _∞ filter designs for two-dimensional (2-D) discrete systems in Roesser model with polytopic uncertainties. The filters to be designed are assumed to be with additive norm-bounded coefficient variations which reflect the imprecision in filter implementation. The complicated filter design problem is successfully tackled by using the slack variable technique and imposing a structural restriction on the slack matrix. Explicit expressions of the non-fragile H ₂ and H _∞ filters are given in terms of solutions to a set of linear matrix inequalities (LMIs). An illustrative example is provided to demonstrate the feasibility and effectiveness of the proposed method.     

A new closed form method for design of variable bandwidth linear phase FIR filter using Bernstein multiwavelets

In this paper, a new method for the design of variable bandwidth linear-phase finite impulse response filters using Bernstein polynomial Multiwavelets is proposed. In this method, approximation has been achieved by linearly combining the fixed coefficient linear phase filters with Bernstein multiwavelets, which are used to tune bandwidth of the filter. Optimisation has been achieved by minimising the mean square error between the desired and actual filter response which leads to a system of linear equations. The matrix elements can be expressed in form of Toeplitz-plus-Hankel matrix, which reduces the computational complexity. The simulation results illustrate significant improvement in errors in passband (e_p), and stopband (e_s) as compared to earlier published work.     

Robust L<Subscript>2</Subscript> - L<Subscript>∞</Subscript> Filtering for Uncertain Nonlinearly Parameterized Stochastic Systems with Time-Varying Delays

This paper is concerned with the problem of robust L₂ - L_∞ filtering for uncertain stochastic time-delay systems in the nonlinear fractional transformation (NFT) form. Attention is focused on the design of both full-order and reduced-order filters, guaranteeing robust stochastic stability and a prescribed level of L₂ - L_∞ performance for the filtering error system. A parameter-dependent Lyapunov functional is employed to solve the problem. The concerned filters are not only parameter dependent but also have the NFT form. Sufficient conditions for the existence of such filters are presented in terms of certain linear matrix inequalities (LMIs). Desired filters are explicitly expressed based on the solutions to the proposed LMIs. A numerical example is provided to demonstrate the effectiveness of the proposed method.     

Signal limitations of the current-mode filters employing current conveyors

It is well known that second-generation current conveyors (CCII) are widely used for the realization of second-order current-mode universal filters. A filter with high-quality factor (Q) and gain constant (K) suffers from various signal swing restrictions especially at its angular resonance frequency (ω₀). This is due to the terminal voltages of the CCIIs limited by the power supply voltages and maximum allowable terminal currents of the CCIIs. In this paper, signal limitations of the CCII-based current-mode filters are investigated in detail. A filter example is given to exhibit the signal limitations of a universal current-mode filter. The time-domain and frequency-domain results of the proposed filter are also given to verify the theoretical analysis.     

Design tables for two active RC circuits realizing low-pass polyonimic filters

Realization of RC-active filters, as proposed by Sallen and Key, consists of cascade connection of suitable second- and first-order building blocks. The paper presents design tables for two active RC circuits realizing low-pass polyonimic filters. The functions realized are of second to eighth-order low-pass Butterworth, Chebyshev (with 0.1, 0.5, 1, 2 and 3 dB ripple) and Bessel variety. This method uses simple op-amp integrator blocks and can equally be applied to both continuous-time and switch-capacitor filter designs. The advantages of this method are: simple method of designing LP filters from second to eighth order using integrator blocks (e.g. MAX 274 and MAX 275); low sensitivity to component values; low spread in component values; good tuning; can tune parameter f ₁ (cutoff frequency). The disadvantages of this method are: no independent adjustment of the cutoff frequency and the Q-factor; fixed gain of unity.     

A Delay Partitioning Approach to H �� Filtering for?Continuous Time-Delay Systems

This paper investigates the problem of delay-dependent H _∞ filter design for continuous time-delay systems. Attention is focused on the design of linear filters guaranteeing a prescribed noise attenuation level in an H _∞ sense. The admissible filters can be obtained from the solution of a convex optimization problem in terms of linear matrix inequalities (LMIs), which can be readily solved via standard software. The crucial issue for solving the filter design problem is the utilization of the delay partitioning idea, which proves to be less conservative than most of the existing results, and the conservatism could be notably reduced by thinning the delay partitioning. Numerical examples are provided to show the effectiveness and the advantage of the proposed filter design method.     

电磁寄生参数在高频SAW滤波器设计中的应用

在设计高频声表面波(SAW)滤波器的过程中,若只考虑封装壳和键合线的电磁寄生参数而忽略汇流条的电磁寄生参数,则SAW滤波器的实际性能易受汇流条寄生参数影响而出现通带波动和驻波增大等问题。该文拟用电声-电磁联合仿真方法设计高频SAW滤波器以解决汇流条寄生参数对SAW滤波器性能的影响。通过此方法研制的滤波器通带插入损耗小于1 dB,波动0.5 dB,通带内驻波最大值2.1,-1.5 dB带宽75.7 MHz,-3 dB带宽84 MHz (相对带宽为4.8%),-30 dB带宽112 MHz,BW_{-3 dB}/BW_{-30 dB}矩形系数1.33。包含封装壳、键合线及汇流条的寄生参数的理论仿真结果与实验测试结果吻合较好,表明了采用此模型设计高频SAW滤波器的可行性。     

Microstrip bandpass filters on substrates with high permittivities

A new class of compact microstrip bandpass filters, the stepped-impedance resonators of which are located close together at a gap of 0.1–0.2 mm, is described. Basic two- and three-element sections of microstrip filters, which are designed around stepped-impedance impedance resonators used to implement tiny selective devices with overall sizes and characteristics comparable to those of microwave ceramic filters, are proposed. It is justified that the mentioned filters can be equipped with closely neighboring metallic shields whose heights are equal to the substrate thickness. As a consequence, these filters turn out to be thinner. The frequency responses of experimental microstrip filters operating at frequencies of 1.75–2 GHz and manufactured on the 1-mm-thick substrates with the permittivity ɛ _r = 100 have been analyzed. The three-pole microstrip filter with a shield (its operating frequency is 1.96 GHz, and sizes are 5 × 5 × 1.5 mm) has been simulated. It is demonstrated that new microstrip filters can be competitive with low-sized ceramic filters in certain applications.     

Separate/joint optimization of error feedback and realization for roundoff noise minimization in a class of 2-D state-space digital filters

Techniques for the separate/joint optimization of error-feedback and realization are developed to minimize the roundoff noise subject to l ₂-norm dynamic-range scaling constraints for a class of 2-D state-space digital filters. In the joint optimization, the problem at hand is converted into an unconstrained optimization problem by using linear-algebraic techniques. The unconstrained problem obtained is then solved by applying an efficient quasi-Newton algorithm. A numerical example is presented to illustrate the utility of the proposed techniques.     

600V HVIC高噪声抑制电平移位电路

A novel level shift circuit featuring with high dV/dt noise immunity and improved negative V_S capacity is proposed in this paper.Compared with the conventional structure,the proposed circuit adopting two cross-coupled PMOS transistors realizes the selective filtering ability by exploiting the path which filters out the noise introduced by the dV/dt.In addition,a differential noise cancellation circuit is proposed to enhance the noise immunity further.Meanwhile,the negative V_S capacity is improved by unifying the detected reference voltage and the logic block’s threshold voltage.A high voltage half bridge gate drive IC adopting the presented structure is experimentally realized by using a usual 600 V BCD process and achieves the stable operation up to 65 V/ns of the dV/dt characteristics.     

High output impedance current-mode lowpass,bandpass and highpass filters using current controlled conveyors

Three new current-mode second-order filter configurations which employ one or two current controlled conveyors (CCCIIs) and three passive elements are presented. Each proposed filter can realize one of the bandpass, lowpass or highpass responses all at high impedance outputs. The proposed filters offer current-control of pole angular frequency ω_o without disturbing the parameter ω_o /Q. No component matching is required and all the passive and active sensitivities are low. PSPICE simulation results are given to confirm the theoretical analysis.     

Current-mode active-only universal filter

A novel current-mode active-only universal filter based on and employing three DO-CCCIIs and two OAs is introduced. The circuit is fully integrable and programmable, and implements all the five generic filtering functions. The three basic filtering responses LP, BP and HP are implemented simultaneously by the circuit, while AP and notch signals can be realized simply by connecting appropriate node currents. The currents are available at high output impedances, so the synthesized filter can be cascaded without additional buffers to realize higher order filters. The filter performance factors ω ₀ and Q are electronically tunable in an orthogonal manner through separate bias currents of the CCCII. The PSPICE simulation was carried out to realize the proposed circuit.     

Method for FIR filters design with compressed cosine using Chebyshev's norm

This paper considers a new method for FIR filters design. The method uses an L_∞ optimality norm. To achieve a better approximating effect, a new modulating function which compresses the oscillations of the cosine is proposed. A parameter sets the gradient of the modulating function, with respect to the oscillations’ compression. The approximating polynomial is carried out using Remez’ exchange algorithm. An optimal polynomial with lowest possible (four) degree, that approximates an ideal filter's response with high precision is proposed. With the proposed method a FIR filter with arbitrary specifications can be designed. Design examples of FIR filters with a minimization of calculation are performed. The obtained filter's responses are close to the ideal response. The design examples demonstrate that the proposed approach may be a good alternative in several applications.     

Design of FIR digital filters using prescribed subfilters

A method for the design of linear-phase digital filters by the tapped cascaded interconnection of identical subfilters is presented. The method is an extension of the method proposed by Saramaki (1987). An example is given to show that the number of distinct multipliers of the filter determined by the proposed method is less than that of filters determined by Saramaki's method (1987). We also consider the case in which the subfilters are determined by multiple use of a single filter. In particular, if we can make the subfilters multiplierless then the number or multiplications per sample required to implement the overall filter is less than that required by the direct-form minimax method. Methods for the design of computationally efficient filters are also developed based on the proposed transformation method. The multiplication rate of the overall filter is the same as that of the prototype filter. It is very low as compared to that designed by the equivalent direct-form minimax method. With the proposed transformation method, methods for the design of a filter having nth-order tangency at both ends (0, π) are also developed. This is an extension of Vaidynathan's method (1985) and the proposed transformation method. The advantages of the method are that the resulting filters have very flat passbands and the stopbands are computationally efficient.     

A New Approach to Robust H<Subscript>∞</Subscript> Filtering for Uncertain Systems with Both Discrete and Distributed Delays

This paper is concerned with robust H_∞ filter design for a class of linear distributed delay systems with norm-bounded time-varying parameter uncertainties. The distributed delays are assumed to appear in both state and measurement equations. A new design method is proposed by introducing some relaxation matrices and tuning parameters, which can be chosen properly to lead to a less conservative result. A sufficient condition is obtained to guarantee the existence of desired H_∞ filters, which can be constructed by solving a convex optimization problem. A numerical example is included to illustrate the effectiveness and the reduced conservatism of the proposed design technique.     

Continuous Time Universal Filters using Unity Gain Cells

A new circuit configuration for continuous time universal filters using current and voltage followers is proposed. The new configuration employs small number of passive elements. It provides independent control over all filterdesign aspects mainly the natural frequency, ω_o, quality factor, Q, and gain. It also allows complete MOS non-linearity cancellation, thus is suitable MOS-C continuous-time fully integrated filters. Analysis ofthe non-idealities associated with the active elements is included. HSpice simulations that confirm theoretical analysis are included.     

Synthesis of class-AB log-domain filters based on nonlinear transconductance

In this paper a new generalized method for synthesis of class-AB current-mode log-domain filters, using nonlinear transconductance cell, is presented. The proposed nonlinear transconductance cell is designed by employing floating-gate MOS (FG-MOS) transistors that operate in weak inversion. It allows deriving current-mode nonlinear transconductance-capacitor (G_m-C) structure from its corresponding conventional transconductance-capacitor (g_m-C) in a systematic way. In this method, synthesis complexity is independent of system size, and thus high-order systems can be readily realized. In addition, it keeps the transconductance-capacitor topology invariant, leading to a very regular, general and simple topology. The filters are designed based on the transistors that are working in weak inversion and feature, low supply voltage, low-power consumption, immune to body effect and with low circuit complexity. For illustration of this new synthesis method, two different filters were designed and verified by simulation. The simulation results by HSPICE show the validity of the proposed technique.     

Synthesis of 3-D Separable-Denominator State-Space Digital Filters with Minimum L 2-Sensitivity

This paper deals with the analysis and minimization of L ₂-sensitivity for three-dimensional state-space digital filters which are separable in the denominator. First, a novel expression for evaluating the L ₂-sensitivity is developed in closed form. An iterative procedure for synthesizing the optimal filter structures is then presented so as to minimize the L ₂-sensitivity. Finally, a numerical example is given to illustrate the utility of the proposed technique.