对线性载波调制信号采样的研究

分析了线性载波调制信号经欠采样后,满足一定的条件时可以恢复基带信号波形。给出了达到这种频谱重叠条件的采样率的下限即采样率等于2倍的基带信号带宽以及何时能取到这一下限。同时提出对数字载波调制系统的采样不需要重建波形而只要恢复码元序列的思想。应用修正的Gardner算法可部分地解决采样时钟偏差对信号恢复的影响。     

使用△-∑转换器进行同步采样(下)

CLK与SCLK的计时 不论系统中ADC的数量是多少,一定要保持ADS1252中DOUT/DRDY的计时关系.     

使用△-∑转换器进行同步采样(上)

同步采样的重要性 在大多数控制算法中,经常需要获得系统在某个特定时刻多个物理属性的值.我们通常将需要同时获得多种模拟属性值的情况称作"同步采样".确定马达转轴的角度位置就是这样一个例子.     

Digital Hysteretic Voltage-Mode Control for DC–DC Converters Based on Asynchronous Sampling

This paper investigates a digital voltage-mode controller for dc–dc converters based on hysteresis modulation. The control structure implements a high-bandwidth hysteretic differentiator as its main building block, and realizes a nonconventional structure of PID compensation with performances comparable to analog hysteretic controls, thus breaking the bandwidth and dynamic limitations commonly encountered in typical digital control arrangements. The employment of an asynchronous A/D converter based on the threshold inverter quantization concept dramatically shrinks the average delay time that separates the sampling instant from the corrective control action. Moreover, the hysteretic nature of the derivative action results in an inherent nonlinear response to large signal load variations, which translates into fast control intervention and reduced settling times. The hysteretic differentiator employs a ring-oscillator-based modulator, which ensures resolution up to 390 ps without asking for a high-frequency clock. Both the 6-bit asynchronous A/D converter and the ring-oscillator-based modulator are designed and manufactured in the same IC using a standard 0.35 $mu$m CMOS process. Analytical modeling, computer simulations, and experimental results on a synchronous buck converter confirm the validity of the approach and the dynamic performances achievable by the proposed control architecture.      

Digital Peak Current Control for Switching DC–DC Converters With Asymmetrical Dual-Edge Modulation

An asymmetrical dual-edge modulation (ADM) method applied to digital peak current (DPC)-controlled switching dc–dc converters is proposed in this brief. Steady-state and transient performance comparison of DPC-controlled buck converters with ADM and conventional symmetrical dual-edge modulation (SDM) is presented and verified by experimental results. Comparison studies show that the steady-state and transient performances of DPC with ADM are better than those of DPC with SDM.      

矩阵变换器的间接空间矢量控制

矩阵变换器是一种新型的电力电子技术,具有能量可双向流通,可产生正弦输入电流和输出电压以及输入功率角可调等优点。文章基于矩阵变换器空间矢量调制法,分析虚拟整流器和逆变器的空间矢量调制,综合两个过程,得到一种直接的交-交变换器,利用MATLAB的仿真模块组建成矩阵变换器的仿真模型。仿真结果验证了空间矢量调制策略的有效性,矩阵变换器的优越性。     

脉冲宽度调制直流变换器的应用

本文详细介绍了Ｍａｘｉｍ公司脉冲宽度调制直流变换器ＭＡＸ７２４／７２６的原理和应用,包括降压变换器、升压变换器、逆向变换器。提供了典型应用电路图、设计公式以及关键事项。     

矩阵式变换器的等效电路模型研究

本文把矩阵变换器分成五个部分，分别应用PARK变换求出相应的等效电路，然后综合成不含开关元件的矩阵变换器线性定常电路模型。运用线性电路的分析方法得出输入功率因数、输出电压增益、输入电流、输入有功功率、无功功率的数学模型，提出了矩阵变换器输入功率最优控制的概念，推出满足这一最优控制的表达式。最后，利用MATLAB进行了有关仿真分析，验证了PARK变换在矩阵变换器研究中的可行性。     

基于Radon模糊图变换的数字采样信号快速调频参数估计

Radon模糊图转换法(RAT)调频参数估计是模糊图平面过原点直线的一维搜索.RAT直接求和计算方法计算量大,很难实时计算.本文基于模型法研究数字信号RAT参数估计的快速算法,给出了多分量线性调频(LFM)信号模型、RAT模型法参数估计及多分量信号的逐次消去信号检测方法,提出了RAT模型法快速调频参数估计算法,并提出剩余展宽系数来分析调频参数估计性能,同时进行了计算量分析.数字仿真表明本算法在高/低信噪比均能很好地接近Cramer-Rao限.该方法速度快且不需要数据矩阵储存,在多分量调频参数估计中有很好的应用前景.     

Hybrid Carrier and Modulation Tracking Loops

The tracking loops presented herein exploit the coherency of the observed data sidebands at the carrier frequency for improvements in phase-coherent tracking, telemetry, and command system performance. The loop is motivated by one aspect of generalized harmonic analysis, viz., the so-called cross spectrum. The basic idea of the loop centers around using the power in the composite received signal (sidebands including cross-modulation components) to enhance the signal-to-noise ratio in the carrier tracking loop, thereby reducing the noisy reference loss and ultimately the subcarrier reference jitter, the symbol sync jitter, and the error probability of the data detector. The modulation from the extracted sidebands is removed in such a way that the coherence power in the data sidebands can be used for tracking at the carrier frequency.     

Unidimensional Modulation Technique for Cascaded Multilevel Converters

This paper presents a simple and low-computational-cost modulation technique for multilevel cascaded H-bridge converters. The technique is based on geometrical considerations considering a unidimensional control region to determine the switching sequence and the corresponding switching times. In addition, a simple strategy to control the dc-voltage ratio between the H-bridges of the multilevel cascaded converter is presented. Examples for the two-cell topology are shown, but the proposed technique can be applied to develop modulation methods for a higher number of H-bridges. Experimental results are presented to validate the proposed technique.      

Importance Sampling Evaluation of Digital Phase Detectors With Carrier Phase Tracking: A Large Deviations Approach

This paper applies large deviations theory (LDT) to the design of efficient importance sampling (IS) simulation of $M$-ary digital phase detectors subject to random carrier phase drift within symbol interval. Phase tracking is accomplished by extended Kalman–Bucy filters or dedicated stochastic nonlinear filters. The LDT approach relies essentially on the properties of the receiver's error sets, which present unique topological features in an N-dimensional space. We show how to derive the referred topological properties for the particular phase modulating sequences and receiver solutions adopted. The proposed methodologies lead to very high simulation gains both for the assessment of the error floors induced by the random phase drift and for the scenarios where simultaneous random phase and channel noise preclude the derivation of the error regions.      

一种应用于流水线A/D转换器的数字校准算法

通过输入比较器阈值电压到流水线电路计算跳变点高度，重新计算权重，进行数字校准。这种校准方法与数字冗余结合，属于纯数字电路实现，在可实现性与可靠性上具有很大的优势。仿真结果表明，这种方法能保证高精度。     

一种适用于低电压模数转换器的新型采样开关

提出了一种适用于低电源电压的新型高线性度采样开关.与传统低电压采样开关相比,这种新型采样开关不仅消除了MOS开关由于栅源电压随输入信号变化所引入的非线性,而且进一步消除了MOS开关由于阈值电压随输入信号变化引入的非线性.这是通过采用一个与采样MOS开关具有相同阈值电压的"复制"开关得以实现的.基于Chartered 0.35μm标准CMOS工艺,文中设计了一个此类新型MOS采样开关,在输入信号为0.2MHz正弦波,峰峰值为1.2V,采样时钟频率为2MHz时,无杂散动态范围达到111dB,比栅压自举开关提高了18dB;同时导通电阻的变化减小了90%.这种新型采样开关特别适用于低电压,高精度模数转换器.     

A Novel Sampling Switch Suitable for Low-Voltage Analog-to-Digital Converters

提出了一种适用于低电源电压的新型高线性度采样开关.与传统低电压采样开关相比,这种新型采样开关不仅消除了MOS开关由于栅源电压随输入信号变化所引入的非线性,而且进一步消除了MOS开关由于阈值电压随输入信号变化引入的非线性.这是通过采用一个与采样MOS开关具有相同阈值电压的"复制"开关得以实现的.基于Chartered 0.35μm标准CMOS工艺,文中设计了一个此类新型MOS采样开关,在输入信号为0.2MHz正弦波,峰峰值为1.2V,采样时钟频率为2MHz时,无杂散动态范围达到111dB,比栅压自举开关提高了18dB;同时导通电阻的变化减小了90%.这种新型采样开关特别适用于低电压,高精度模数转换器.     

Digital Single-Sideband Modulation

This paper considers digitized Weaver modulators for single-sideband modulation that can be used in radio communications and telemetering. A system of 12 such modulators to process 12 analog signals digitally is replaced by six multiplex modulators at the cost of additional computation at the input but with an overall reduction in computation time and a higher degree of accuracy. A unique digital filter is developed that can interpolate and output samples at multiples of the input sampling rate and exhibits a passband that occurs above the Nyquist frequency with no apparent distortion effects. A discussion of the Fortran simulation of a combined modulator-demodulator structure is included to verify the effectiveness of this scheme.     

负载点转换器的数字电源控制

数字控制方法具有许多应用潜力,利用它来代替传统模拟控制技术的想法对于那些必须在其电路板上控制多个电源电压的设计人员而言颇具吸引力.本文介绍了一些最近即将面市的新型控制器,并说明它们在负载点应用中的一些优势和易用性.     

Continuous-Time Digital Controller for High-Frequency DC-DC Converters

This paper introduces a voltage mode digital controller for low-power high-frequency DC-DC switch-mode power supplies (SMPS) that has fast transient response, approaching physical limitations of a given power stage. In steady state, the controller operates as a conventional pulsewidth modulation regulator and during transients it utilizes a novel fast voltage recovery mechanism, based on real-time processing of the output voltage in digital domain. This continuous-time digital signal processing mechanism is implemented with a very simple processor consisting of a set of asynchronous comparators, delay cells, and combinatorial logic. To eliminate the need for current measurement and calculate the optimal switching sequence of the power stage transistors, the processor performs a capacitor charge balance algorithm, which is based on the detection of the output voltage peak/valley point. The effectiveness of the controller is demonstrated on an experimental 5 W, 5 V to 1.8 V, 400 kHz buck converter. The converter recovers from load transients through a single on-off action of the power switch, virtually reaching the shortest possible time, limited by the values of the power stage filter components only.     

Parameter-Independent Time-Optimal Digital Control for Point-of-Load Converters

In this paper, a digital control approach is investigated for time-optimal load step response of dc–dc synchronous buck converters intended for point-of-load (PoL) applications and employing low-equivalent series resistance ceramic output capacitors. Unlike previously reported approaches, the proposed technique is insensitive to converter parametric variations and design uncertainties, as its operation does not rely on the knowledge of the output filter inductance or capacitance. The time-optimal response is achieved through a single on/off switching action undertaken as soon as a load transient is detected. In its most general formulation, the proposed technique automatically incorporates adaptive voltage positioning (AVP) regulation, according to the typical droop design guidelines for powering modern microprocessors. A simpler version, suitable for voltage-mode controlled PoL converters not requiring AVP positioning, is also presented. The technique employs an asynchronous A/D conversion scheme, which quantizes the converter state variables and triggers a nonlinear, event-based digital controller whenever a quantization level transition is detected. Additional sensing requirements are not needed, since the time-optimal transient is achieved through the measurement of the output voltage and, whenever AVP regulation is needed, of the phase currents. Effectiveness and properties of the proposed robust time-optimal approach are validated through both computer simulations and experimental tests on a synchronous buck converter prototype and a VHDL implementation of the control algorithm on an field programmable gate array device.      

数字GFSK调制解调的算法与实现

高斯频移键控（Gauss frequencyShift Keying,GFSK）是一种广泛应用于低数据速率的个人通信标准（如蓝牙）的调制方式。限于低功耗和低成本,GFSK收发机通常在模拟域设计。为了改进误比特率和提高不同的复杂设备之间的综合能力,数字GFSK调制解调技术应运而生。在该文,将着重讨论最小平方（LS）与最大似然估计法（MS）是利用计算机辅助技术来实现GFSK载波恢复。通过估测误差方差的分析,我们发现LS/ML载波频率偏移估计法优于传统DFT法。除此之外,本方法也能有效地处理直流的数据源。通过在MATLAB上进行仿真,在高斯白噪声环境中实现了理想误码率的GFSK传输仿真。