Simultaneous amplitude and phase approximation for fir filters

An FIR filter design method with simultaneous amplitude and phase approximation is presented. Two components are proposed in the design method: simultaneous amplitude and phase interpolation in the passband and amplitude interpolation in the stopband. These interpolations are implemented by the Remez exchange algorithm. The polynomials for the interpolations are generated by recurrence formulae and the recurrence coefficients are calculated by a recursive method. the properties of the filters designed with the simultaneous approximation are investigated and compared with those of exact linear and minimum phase filters.     

Phase amplitude coupling in spectral phase modulation

We report the experimental study of spatio-temporal coupling in spectral phase modulation. Spectral phase modulation relies on the creation of a Fourier plane where spectral components are dispersed and independently focused on a modulator, which allows to locally change the optical path. Spatio-temporal coupling arising from the principle of spectral phase modulation in itself has been experimentally studied for various typical phase modulations and compared to simulations     

Characterization of phase and amplitude comparators in UHSdirectional relays

In this paper, conventional techniques to compute the phase angle between a voltage and a current waveform are applied to assess the directionality as it is necessary in ultra high speed (UHS) directional relays. It is shown that with this type of relay the main difficulty stems from the fact that in order to compute the angle, a prior knowledge of the amplitudes of the superimposed voltage and current magnitudes is necessary. Therefore very fast algorithms have to be devised that would take into account anticipated values of these magnitudes in order to assure secure trips in the shortest possible time     

相位噪声比对方法和分析

相位噪声比对的目的可以识别实验室间的差异及评价其适用性,保证相位噪声测量结果的质量。阐述了实验室相位噪声比对可以评价参比实验室相位噪声项目校准的技术能力,具有重要的现实意义。比对采用相位噪声标准装置对量值统一校准源进行计量检定的方法,用标准化误差En值对参比实验室测量结果的质量进行评价,结果表明实验室的相位噪声标准性能完好,能够保证测量结果的质量,具有较高的置信度,验证了实验室的持续能力。     

一种利用矢网测试接收机幅相特性的方法

幅相一致性和幅相线性是影响接收机性能提高的重要因素,也是精确测试的难题。本文在简要介绍矢网测试原理的基础上,给出了利用安捷伦公司矢网N5242A测试上述两项指标的方法,给出了测试结果。实际测试结果表明利用矢网测试接收机的幅相一致性和线性是高效可行的。此外,文中还提出了利用矢网测试应该注意的问题。     

锁相环相位噪声的研究与仿真

锁相环在数字电路中一个重要的应用就是作为频率合成器产生高性能的时钟。本文介绍了锁相环的工作原理,重点研究了锁相环输出时钟的相位噪声的影响因素。通过对其线性环路模型进行频域分析,运用反馈控制理论,讨论了环路内各器件的噪声对其输出信号相位噪声的影响。得到了锁相环能良好改善环路带内噪声的分析结果,并且利用ADS搭建仿真电路,验证分析结果,为今后高性能频率合成器的设计和应用提供参考依据。     

改进的幅相重构算法抗主瓣干扰研究

主瓣干扰一直是雷达抗干扰技术难以解决的问题.实验发现常规幅相重构算法对非恒模干扰的抑制效果不好.针对主波束方向的压制性强干扰,采用滑窗改进的幅相重构算法进行抑制.即使干扰不完全具备恒模特征,也可以通过细化采样窗长估计此采样窗口内所有采样点的干扰幅度,然后每次滑动窗口估计下一个采样点的幅度信息,并且利用接收信号的单位向量逐点估计相位信息,及时解析重构干扰信号,最后从雷达接收的和信号中将重构得到的干扰消去,从而达到抑制主瓣干扰的目的.仿真实验获得较理想的干扰相消效果,此方法对雷达抗干扰能力的提升具有重要的意义.     

Transfer functions interpolating an ideal amplitude with arbitrary phase and delay

A method is presented to generate polynomials with phase values and delay (first derivative) specified at given frequencies. Then a closed form solution is described for the scattering transfer function S₁₂(p) of a resistively terminated lossless reciprocal two-port network with ideal amplitude and arbitrary phase and delay.     

Lowpass approximations of a constant amplitude with arbitrary phase and delay

A review is made of recent developments to the simultaneous lowpass approximation problem of amplitude, phase and delay. the closed from solutions (reciprocal and non-reciprocal) are expressed in terms of the arbitrary phase and delay polynomials (APD).     

On the problem of filters with arbitrary amplitude and phase constraints

A simplified method—based on the concept of reflection filters—is presented for designing linear phase filters with arbitrary amplitude to phase constraints. This method starts with transfer functions with 2: 1 amplitude to phase constraints, and through varying the recurrence relation of the polynomials involved, transfer functions with more selective amplitude are obtained.     

On the simultaneous amplitude and phase approximations of wave digital lattice filters

The paper presents new solution for the problem of simultaneously approximating the amplitude and phase functions of wave digital lattice filters. The approximation is relying on translating the amplitude and phase specifications into corresponding specifications for the difference and sum phase functions of the two branch polynomials. As a consequence, the phase specifications for each of the two branch polynomials is determined. Accordingly, these two polynomials are generated such that the amplitude and phase functions are approximated alternatively. This means that while one of these functions is approximated, the other is fixed. By iterating this alternative process, the two functions converge to their optimal response. Copyright © 2003 John Wiley & Sons, Ltd.     

Analysis of flicker noise conversion to phase noise in CMOS differential LC oscillators

An analysis of the flicker noise conversion to close‐in phase noise in complementary metal‐oxide semiconductor (CMOS) differential inductance‐capacitance (LC)‐voltage controlled oscillator is presented. The contribution of different mechanisms responsible for flicker noise to phase noise conversion is investigated from a theoretical point of view. Impulse sensitivity function theory is exploited to quantify flicker noise to phase noise conversion process from both tail and core transistors. The impact of different parasitic capacitances inside the active core on flicker noise to phase noise conversion is investigated. Also, it is shown how different flicker noise models for core metal‐oxide semiconductor (MOS) transistors may result in different close‐in phase noise behaviors. Based on the developed analysis, design guidelines for reducing the close‐in phase noise are introduced. Copyright © 2015 John Wiley & Sons, Ltd.     

低压电力线信道脉冲噪声的幅值与宽度特征

在低压电力线信道的各种噪声中,脉冲噪声可能会使通信系统引起瞬间误码率升高,严重影响了低压电力线通信可靠性。根据脉冲噪声的幅值和宽度与背景噪声的区别,即幅值相差10~50 d B,且脉冲宽度约为几十微秒到几毫秒的特性,在时域中,通过窗函数设定脉冲噪声门限值过滤低压电力线背景噪声,根据实测数据计算出信号噪声中的最大值和最小值,将信号变化范围划分为四组矩形窗函数,以识别出50~200 k Hz频率范围的脉冲噪声。     

Towards minimum achievable phase noise of relaxation oscillators

A relaxation oscillator design is described, which has a phase noise rivaling ring oscillators, while also featuring linear frequency tuning. We show that the comparator in a relaxation‐oscillator loop can be prevented from contributing to 1/f² colored phase noise and degrading control linearity. The resulting oscillator is implemented in a power efficient way with a switched‐capacitor circuit. The design results from a thorough analysis of the fundamental phase noise contributions. Simple expressions modeling the theoretical phase noise performance limit are presented, as well as a design strategy to approach this limit. To verify theoretical predictions, a relaxation oscillator is implemented in a baseline 65 nm CMOS process, occupying 200 µm × 150 µm. Its frequency tuning range is 1–12 MHz, and its phase noise is L(100kHz) = ?109dBc/Hz at f_osc = 12MHz, while consuming 90 μW. A figure of merit of ?161dBc/Hz is achieved, which is only 4 dB from the theoretical limit. Copyright © 2012 John Wiley & Sons, Ltd.     

低相位噪声参考信号发生器的设计

参考信号发生器是频率合成系统的重要组成部分,是实现低噪声频率合成的基础。本文介绍了产生低相位噪声参考信号常用的技术方法,重点讨论了如何基于锁相环频率合成法实现极低相位噪声参考发生器的设计。最后基于本文讨论的技术方法,设计出了一种具有极低相位噪声的参考信号发生器,并给出了实验结果。该参考信号发生器应用于某高纯微波信号源中,取得了很好的效果。     

Thermal and flicker phase noise analysis in rotary traveling-wave oscillator

This paper analyzes the thermally induced phase noise and the up-conversion of flicker noise into phase noise of rotary traveling-wave oscillator (RTWO). Based on the analyses, this paper extracts the closed-form formulas for the thermal and flicker phase noise of the RTWO. This paper compares the theoretical results with appropriate simulations to evaluate the accuracy of the derived closed-form formulas. Comparisons confirm the accuracy of the extracted phase noise formulas. By using the presented straightforward approach along with accurate phase noise formulas, the designers can understand the RTWO ' s design tradeoffs. Also, they can design the RTWO for a specific phase noise without needing lengthy simulations.     

Robust simultaneous amplitude and phase approximations oriented to bandpass wave digital lattice filters

A straightforward design method is delivered for bandpass wave digital lattice filters satisfying arbitrary amplitude and linear phase specifications. The optimality and efficiency of this method are ensured by two sources. On the one hand, the approximation is carried out directly without the need to apply frequency transformation techniques. On the other, the amplitude and phase specifications are approximated simultaneously. The approximation process is relying on the pre-construction of one of the two branch all-pass functions to exhibit exact linear phase. The other all-pass function is determined such that it controls the amplitude and/or phase responses in the passband and the two stopbands. Accordingly, the approximation problem is reduced to constructing a strictly Hurwitz polynomial specified by its phase within the Nyquist range. The approximation problem is solved by applying interpolation techniques combined with the iterative Remez-exchange algorithm. The realization of the resulting filter is carried out according to explicit formulae. The delivered method is applied through two examples illustrating its efficiency and reliability. © 1998 John Wiley & Sons, Ltd.