Analysis and Algorithm Simulation of Forward-link CDMA Signal Spectral Regrowth

In CDMA systems, the Radio Frequency Power Amplifier (RF PA) is the most important device. As is known, the nonlinearity of the power amplifier always attracts people’s attention. Since the envelope of CDMA is time-varying, it is of great significance to calculate the distortion caused by the transmitter in the communication system of CDMA. The odd order nonlinear intermodulations of the transmitter expand the frequency spectrum of the CDMA signal, which is called spectral regrowth.…     

前向信道CDMA信号频谱增生的算法与仿真实验

利用幂级数和高阶累计量的统计方法,推导出基于IS-95模型前向信道的CDMA(码分多址)信号通过弱非线性RF功率放大器产生的频谱增生的严谨表达式,通过仿真验证其正确性.并由此获得了经该放大器特征模型变换的输出信号自相关函数的解析表达式.用三阶截断点IP3表示了包含带内和带外电抗的记忆效应三阶非线性.频谱增生的分析结果可直接用于工程计算,这对于确定射频功率放大器最佳的工作条件是十分有价值的.根据推导出的算法进行仿真,并与ADS软件进行仿真结果进行比较,以说明其正确性.     

Effects of signal PDF on the identification of behavioral polynomial models for multicarrier RF power amplifiers

This paper proposes an experimental study of the sensitivities of the power amplifier modelling and their influences on the system??s identification. Two memory polynomial models are widely investigated in the behavioural modelling and linearization of RF power amplifiers (PAs). In order to improve the accuracy of the behavioural modeling versus identification, we assess the performances of these models under different signal bandwidths, statistics and signal distributions. For this purpose, normalized mean square error has been used to compare the model output to measured data when the PA is driven under multi-carrier input signals. Measurement results and simulation have been carried out and the results demonstrated the effects of the signal characteristics on the performances of the model. Multi-carrier wideband code-division multiple access and multi-tone signals were used with an experimental Doherty amplifier. The obtained results revealed a degradation of the polynomial model performances when the statistics of the input signals change with similar peak-to-average power ratio.     

A Low-Jitter Polyphase-Filter-Based Frequency Multiplier With Phase Error Calibration

A new low-jitter polyphase-filter-based frequency multiplier incorporating a phase error calibration circuit to reduce the phase errors is presented. Designing with a multiplication ratio of eight, it has been fabricated in a 0.13-mum CMOS process. For input frequency of 25 MHz, the measured jitter is 2.46 ps (rms) and plusmn9.33 ps (pk-pk) at 200-MHz output frequency, while achievable maximum static phase error of the calibration circuit is 2.4 ps. The calibration leads to the normalized rms jitter of 0.049%.     

Energy and peak-current per-cycle estimation at RTL

We present novel macromodeling techniques for estimating the energy dissipated and peak-current drawn in a logic circuit for every input vector pair (we call this the energy-per-cycle and peak-current-per-cycle, respectively). The macromodels are based on classifying the input vector pairs on the basis of their Hamming distances and using a different equation-based macromodel for every Hamming distance. The variables of our macromodel are the zero-delay transition counts at three logic levels inside the circuit. We present an automatic characterization process by which such macromodels can be constructed. The energy-per-cycle macromodel provides a transient energy waveform, and can also be used to estimate the moving average energy over any time window, whereas peak-current-per-cycle macromodel provides peak-current which can be used for studying IR drop problems. Some key features of this technique are: 1) the models are compact (linear in the number of inputs); 2) they can be used for any input sequence; and 3) the characterization is automatic and requires no user intervention. These approaches have been implemented and models have been built and tested for many circuits. The average errors observed in estimating the energy-per-cycle and peak-current-per-cycle are under 20%. The energy-per-cycle model can also be used to measure the long-term average power, with an observed error of under 10% on average.     

A Ku-BAND WAVEGUIDE FREQUENCY MULTIPLIER USING HARMONIC-REJECTION MICROSTRIP PATCH TRANSITIONS

A compact frequency multiplier waveguide module is built by placing a planar microstrip section between two rectangular waveguides. The size of the microstrip section is minimized by eliminating all harmonic band-rejection filters. Special feed locations for the input waveguide-to-microstrip transition patches provide the second-harmonic rejection at the input, and a balanced circuit configuration formed with a pair of transistors produces the pump signal cancellation at the output. The measurements on a fully-assembled waveguide module showed a peak frequency conversion gain of-2.3 dB at 16.7 GHz with the associated output power level of 6 dBm.     

低延迟低电压电流比较器

设计了一种基于改进共源共栅电流镜的CMOS电流比较器,该比较器在1 V电压且电压误差±10%的状态下都正常工作,同时改进后的结构能够在低电压下取得较低的比较延迟。电路的输入级将输入的电流信号转化为电压信号,电平移位级的引入使该结构能够正常工作在不同的工艺角和温度下,然后通过放大器和反相器得到轨对轨输出电压。基于SMIC 0.18μm CMOS工艺进行了版图设计,并使用SPECTRE软件在不同工艺角、温度和电源电压下对电路进行了仿真。结果表明,该电路在TT工艺角下的比较精度为100 nA,平均功耗为85.53μW,延迟为2.55 ns,适合应用于高精度、低功耗电流型集成电路中。     

SOA工作条件对全光异或输出性能的影响研究

理论分析了SOA动态模型和SOA-MZI全光异或原理,采用光通信系统设计软件OptiSystem搭建了基于SOA-MZI的全光异或实验模型,仿真研究了注入SOA的数据信号光功率、连续探测光功率、偏置电流等工作条件对异或输出消光比、Q值以及误码性能的影响,取得了一组最佳工作条件,即数据信号光功率为3dBm,连续探测光功率为0dBm,偏置电流为600mA,此时可以得到最佳的异或输出性能:消光比约11.5dB,Q值约22,误码率约10-108量级。研究方法和相关结论可以推广到基于SOA的其他全光信号处理应用中,为未来全光网络的全面建设做准备。     

基于石英基片的二毫米频段三倍频器的研制

介绍了一个基于石英基片的二毫米频段三倍频器.采用反向并联变容二极管对结构实现倍频.建立了该二极管管对的等效电路模型并提取了模型参数.设计实现的倍频器输入为K型接头结构,输出为WR-8波导结构.获得的倍频器在输出频率为112.8～118.2 GHz范围内,输出功率大于0 dBm,最大输出功率超过2 dBm,最小倍频损耗为...     

一种低纹波输出非标准正弦电流有效值转换电路

首先介绍了目前用于电流有效值转换的方法,分析了每种方法的特点,并以AD637芯片为核心搭建了典型应用电路,通过输入方波信号,发现其输出纹波含量较高,输出结果含有较大误差。在AD637典型应用电路的基础上搭建了基于Sallen-Key滤波电路的非标准正弦电流有效值转换电路,并通过优化滤波电路的参数,使得输出纹波含量降低为典型应用电路的10%以下,提高了非标准正弦电流信号有效值转换的精度。     

A novel monolithic white LED driver with dual dimming mode

This paper presents a hysteretic-current-control LED driver with the dual dimming mode. This novel monolithic driver includes an output switch and a high-side output current sensing circuit using an external resistor to set the nominal average output current (I_OUTnom). By applying an external control signal to the DIM pin, it can alter flexibly the control mode between the analog (DC) and switching (PWM) dimming. In the DC dimming mode, when the input DC control voltage is adjusted from 0.5 to 2.5 V, the average output current can be changed from 20 to 100 % of the current I_OUTnom. While in the switching dimming mode, the output current is proportional to the duty cycle of the input switching signal and changed from about 0 to 100 % of the current I_OUTnom. The driver circuit has been verified in a 0.5 μm HVCMOS process and the die size is about 1.2 × 1.5 mm². This proposed driver can work in 8–40 V power supply, the maximum average output current is up to 1.0 A.     

Interpolative Digital-to-Analog Converters

Interpolative digital-to-analog (D/A) converters produce a final output via a two-step process. First, each digital input word is used to control a circuit whose output oscillates rapidly (i.e., many times faster than new digital input values are provided) between coarsely spaced analog values (i.e., many times coarser than the resolution specified by the input word). Second, the oscillating analog signal is low-pass filtered to give the final output. The oscillation pattern is chosen to produce an average value that corresponds to the fine resolution specified by the input word and to ensure that the power of the error (the difference between the oscillating signal and the desired fine resolution output) occurs predominantly out of band. By this means, high-speed operation reduces the need for many finely spaced analog signal amplitudes, a tradeoff which is especially desirable for integrated circuit implementation. In this paper, the basic operation of interpolative D/A converters is described. Three alternative means of generating patterns are compared with respect to circuit complexity, and amount of baseband distortion introduced. The relative insensitivity of these converters to circuit value variations is emphasized. Applications of the interpolative technique to decoding digital words in both linear and piecewise linearly companded formats are given.     

一种杂波中提取弱小脉冲信号的设计方法

采用巧妙的电路结构和模拟信号处理方式,设计了一种从杂波中提取弱小脉冲信号的电路.首先对输入信号进行饱和放大,然后分两级进行滤波.将一级滤波输出信号与二级滤波输出信号在比较器中进行比较,从而产生脉冲信号,输出脉冲宽度可调.该电路结构简单,使用元器件较少,便于小型化.采用厚膜工艺加工制作该电路.结果表明,该电路的脉冲宽度误...     

基于PWM的D类音频功率放大器的设计

系统旨在设计一种D类功率放大器,以高频三角波作为载波,对音频信号进行采样,生成PWM(Pulse Width Modulation)调制信号.采用高速开关管组成的互补对称式H桥电路对信号的功率进行放大,再将放大后的信号送入4阶Butterworth低通滤波器进行滤波,得到理想的音频信号.系统主要针对音频信号进行处理,对输入频率20 Hz～20kHz,振幅30～250 mV的音频信号可以实现很好的功率放大效果,最大不失真输出功率大于1W,最高效率可达到83％.还能对输入信号进行可调放大,实现信号输出功率可调.     

高功率光纤激光器反向泵浦信号合束器信号光传输效率提升技术研究

在高功率光纤激光器反向泵浦信号合束器的制作过程中,经熔融拉锥后输出端的信号光纤纤芯变细,在与输入端信号光纤熔接时产生模场失配问题,造成反向泵浦信号合束器的信号光传输效率降低。针对这一问题,文中搭建了信号光纤熔接的芯径失配功率损耗模型,简析了光纤熔接时芯径失配与信号光功率损耗的关系。设计了一套泵浦信号反向合束器信号光功率损耗测试系统。提出了一种通过优化反向合束器信号光纤参数,提升反向泵浦信号合束器的信号光功率传输效率的方法,并通过预拉锥工艺,制作出一支25/400 （6+1）×1反向合束器,经测试,信号光传输效率优于98%,实验室使用该反向合束器搭建了一台MOPA结构光纤激光放大器,实现了3 kW稳定输出。     

A BiCMOS continuous-time filter for video signal processingapplications

A fully integrated BiCMOS continuous-time filter for video signal processing applications is presented. It incorporates an input clamping circuit, a third-order equalizer, a fifth-order elliptic filter with sinx/x correction, and a 75-Ω driver. The architectures of the input and output amplifiers as well as the filter and the equalizer are chosen based on the extensive study of circuit structures and Monte Carlo simulation to meet the linearity requirement for the broadcast-quality video system. The complete chip achieves a low-pass filter response with a 5.5-MHz cutoff frequency (f_cc), 0.3-dB passband ripple, 20-ns group delay variation up to 0.9 f_c, and 43-dB attenuation at 1.45 f_c. With a nominal 2-Vpp signal at the output, measured results show 0.2% differential gain, 0.38° differential phase, and 1.7-mV rms noise demonstrating 10-bit linearity in a 1.5-μm 4-GHz BiCMOS process technology. The filter active area is 8 mm² and it dissipates 350 mW in a single 5-V power supply     

一种应用于DC/DC转换器的高效PWM控制电路的设计

本文提出一种用于DC/DC转换器的高效PWM控制电路。该控制电路采用电流控制模式,在宽范围内有着良好的瞬态响应。斜坡补偿信号与误差放大器的输出信号进行叠加,叠加后的信号与电流采样信号进行比较,产生一个占空比信号控制功率管的通断。并且本PWM控制电路中的误差放大器与软启动结合在一起,实现输出电压平滑稳定上升,有效减少了输入电流和输出电压过冲现象,保护了系统安全。     

双向二维快速伺服刀架的前馈控制研究

以压电陶瓷驱动器作为动力输入的快速伺服刀架具有输出力大和高频率响应的优点。压电陶瓷驱动器固有的迟滞现象严重影响了快速伺服刀架的输出定位精度。为解决此问题,通过引入归一化Bouc-Wen模型建立前馈控制补偿器,归一化Bouc-Wen模型解决了经典Bouc-Wen模型中存在的参数冗余问题。获得模型参数后,基于其逆模型搭建了前馈补偿器,并在搭建的实验平台上进行了单/双自由度轨迹跟踪性能测试。实验结果表明,对于等幅正弦波信号,经前馈控制环节补偿下快速伺服刀架的最大轨迹跟踪误差为1.18%,最大轨迹跟踪偏差为2.61%,证明该文所提出的前馈控制补偿器能提高快速伺服刀架的定位精度。     

Integrating acousto-optic channelized receivers

The subject of this paper is acousto-optic channelized receivers with large noncoherent processing gain. A receiver model is developed and the output statistics are derived for signal plus noise input. Noise equivalent bandwidths and signal detection sensitivity are calculated. The implications of large average noise power are discussed. Experimental measurements are in agreement with the theory presented.     

基于高开关频率精确模型的峰值电流型BUCK电源的补偿设计

针对工作在高开关频率的连续导电模式的峰值电流型BUCK电压源,建立了包含功率管导通电阻和寄生参数的精确小信号模型,设计一个新颖的电压环路的补偿模块,优化了瞬态响应。补偿模块仅增加一个极点,消除输出电容寄生电阻引入的零点。在此补偿模块基础上,分析了输出电压Vo对参考电压Vref的传递函数的频率响应,和补偿模块直流增益之间的关系,得出了补偿模块的最佳增益,使得输出电压对参考电压Vref的瞬态响应既快速又没有过冲和振荡,并且在Spice电路仿真中得到验证。