基于CMOS工艺的150 GHz正交外差探测器电路设计

传统太赫兹探测器仅能获取信号幅值信息,为此提出一种正交外差混频结构,可同时获得信号的幅值、相位和极化信息,有效提升探测器的灵敏度和信息量。该探测器基于40 nm互补金属氧化物半导体(CMOS)工艺,在传统吉尔伯特双平衡混频结构的开关级与跨导级之间串联电感,输出级联cascode中频放大器,进一步提高探测器响应电压。经过仿真优化,该探测器在 -50 dBm射频功率,0 dBm本振功率条件下,1 GHz中频信号的电压响应度为1 100 kV/W,噪声等效功率为26.8 fW/Hz^1/2,输出波形显示了良好的正交性。同时,设计了一个1∶8层叠式功分器用于分配本振功率,在150 GHz频率处,该功分器的插入损耗约为5 dB,四路差分输出信号的幅值差为0.8~1.2 dB,相位差为0.4°~1.7°。     

基于径向基函数的微分求积区域分裂法及其应用

1 引言本文提出的基于径向基函数的微分求积区域分裂法是以径向基函数(RBFs)作为微分求积法(DQM)的基函数,并结合区域分裂法(DDM)提出的,结合了上述三种方法的优点,对解决不规则区域上的问题有很高的实用价值．     

Numerical solution of Hammerstein integral equations by using combination of spline-collocation method and Lagrange interpolation

The numerical solutions to the nonlinear integral equations of the Hammerstein-type:

with using B-splines functions are investigated. An interpolation method based on B-splines functions combined with a new collocation method is presented. Finally, for showing efficiency of the method we give some numerical examples.     

一类广义Gauss型求积公式

基于被积函数在n次第一类和第二类Chebyshev多项式的零点处的差商,该本构造了两种Gauss型求积公式. 这些求积公式包含了某些已知结果作为特例.更重要的是这些新结果与Gauss-Turan求积公式有密切的联系.     

Some remarks on the numerical computation of integrals on an unbounded interval

An account of the error and the convergence theory is given for Gauss–Laguerre and Gauss–Radau–Laguerre quadrature formulae. We develop also truncated models of the original Gauss rules to compute integrals extended over the positive real axis. Numerical examples confirming the theoretical results are given comparing these rules among themselves and with different quadrature formulae proposed by other authors (Evans, Int. J. Comput. Math. 82:721–730, 2005; Gautschi, BIT 31:438–446, 1991).      

Performance analysis of a rate adaptive multi-band ultra-wideband system based on quadrature fractal modulation scheme

1 Introduction Wornell and Oppenheim[1,2] first proposed a modulation technique as an interesting potential application of dy-homogeneous signals. Due to the fractal properties of the homogeneous signals, this technique is called fractal modulation afterwards. This class of homogeneous signals remains invariant under scaling of the time axis. Dy-homogeneous signals satisfy the dyadic self-similarity property[3] s (t ) = 2 kH s (2 kt) (1) For all integers k and a constant H, termed the degree…     

A quadrature finite element method for semilinear second‐order hyperbolic problems

In this work we propose and analyze a fully discrete modified Crank–Nicolson finite element (CNFE) method with quadrature for solving semilinear second‐order hyperbolic initial‐boundary value problems. We prove optimal‐order convergence in both time and space for the quadrature‐modified CNFE scheme that does not require nonlinear algebraic solvers. Finally, we demonstrate numerically the order of convergence of our scheme for some test problems. © 2007 Wiley Periodicals, Inc. Numer Methods Partial Differential Eq 2008     

Matrices, moments, and rational quadrature

Many problems in science and engineering require the evaluation of functionals of the form F_u(A)=u^Tf(A)u, where A is a large symmetric matrix, u a vector, and f a nonlinear function. A popular and fairly inexpensive approach to determining upper and lower bounds for such functionals is based on first carrying out a few steps of the Lanczos procedure applied to A with initial vector u, and then evaluating pairs of Gauss and Gauss-Radau quadrature rules associated with the tridiagonal matrix determined by the Lanczos procedure. The present paper extends this approach to allow the use of rational Gauss quadrature rules.     

Positive‐definite q‐families of continuous subcell Darcy‐flux CVD(MPFA) finite‐volume schemes and the mixed finite element method

A new family of locally conservative cell‐centred flux‐continuous schemes is presented for solving the porous media general‐tensor pressure equation. A general geometry‐permeability tensor approximation is introduced that is piecewise constant over the subcells of the control volumes and ensures that the local discrete general tensor is elliptic. A family of control‐volume distributed subcell flux‐continuous schemes are defined in terms of the quadrature parametrization q (Multigrid Methods. Birkhauser: Basel, 1993; Proceedings of the 4th European Conference on the Mathematics of Oil Recovery, Norway, June 1994; Comput. Geosci. 1998; 2 :259–290), where the local position of flux continuity defines the quadrature point and each particular scheme. The subcell tensor approximation ensures that a symmetric positive‐definite (SPD) discretization matrix is obtained for the base member (q=1) of the formulation. The physical‐space schemes are shown to be non‐symmetric for general quadrilateral cells. Conditions for discrete ellipticity of the non‐symmetric schemes are derived with respect to the local symmetric part of the tensor. The relationship with the mixed finite element method is given for both the physical‐space and subcell‐space q‐families of schemes. M‐matrix monotonicity conditions for these schemes are summarized. A numerical convergence study of the schemes shows that while the physical‐space schemes are the most accurate, the subcell tensor approximation reduces solution errors when compared with earlier cell‐wise constant tensor schemes and that subcell tensor approximation using the control‐volume face geometry yields the best SPD scheme results. A particular quadrature point is found to improve numerical convergence of the subcell schemes for the cases tested. Copyright © 2007 John Wiley & Sons, Ltd.     

一类非线性偏积分微分方程二阶差分全离散格式

给出了数值求解一类非线性偏积分微分方程的二阶全离散差分格式.采用了二阶向后差分格式,积分项的离散利用了Lubich的二阶卷积求积公式,给出了稳定性的证明、误差估计及收敛性的结果.