基本电路

0322442X 波段 GaAs 单片五位数字移相器[刊]/申华军//电子器件.—2003,26(2).—229～232(L)0322443有源微分电路设计[刊]/陈思远//电子器件.—2003,26(2).—155～158(L)用理想运放模型设计的有源微分电路的不足表现为,幅频特性有远离微分规律的尖峰,符合微分规律的频带不宽。为此提出在有源微分电路的传递函数中计及实际运放幅频特性,增加与输入电容串联的电阻,可     

三种双T网络陷波电路分析与比较

文章采用Multisim仿真和频谱仪实测的方法研究了三种双T有源陷波器的幅频特性,结果表明双T双跟随电路的优点是阻带外增益为1,Q值可独立调节,特性稳定,缺点是需要两个运放;双T单跟随电路的优点是具有双T双跟随电路的优点而且电路简单,缺点是若反馈网络电阻不满足远小于双T网络电阻的条件,则其中心频率会变小;而双T单运放同...     

基于运放的电流模式滤波电路TT结构分析

本文提出了以基于运放Op-Amp的电流积分器为基础,构成有源RC电流滤波电路MOSFET－C（TT）结构。对这种电流模式TT结构进行了深入的理论研究,并利用PSPICE通用模拟电路程序,对其输出电压幅频特性和相频特性进行了仿真分析。得出了几点实用的结论。     

开关电源环路中的TL43I

虽然上一期文章介绍了如何以TL431实现2类补偿器。然而在补偿电路方面，TL431并非万能药。由于原极点和零点之间以固定系数相关联，采用运放构建的补偿器时，运放的灵活性会降低，而这个运放中可以创建自选的中频带增益。为解决LED串联电阻对可能的增益变化进行钳位的问题，1类补偿器将提供稳定所选转换器时的灵活性，符合期望。然而，这种1类补偿器也有局限，即它不提供任何相位提升。     

CATV系统信号电平"鼓包"现象及应对措施

1“鼓包”现象产生的原因 CATV系统的幅频特性变差是造成“鼓包”现象的根本原因，主要发生在系统的有源和无源器件中，首当其冲是宽带放大器幅度失真，宽带放大器的频带宽，其工作特性不一定都是平直的，而单台放大器的频带幅频特性不良，联级越多叠加效应越明显；其次，系统中应用最多的无源器件如分配器、衰减器、滤波器等带内平坦度不良也会造成电平的“鼓包”现象，这些器件的使用量比有源器件宽带放大器多得多，叠加起来使幅频特性变得更差，另外同轴电缆也可能因质量问题以及老化等原因使信号频率的衰减特性变差，偏离正常的频率特性，便造成“鼓包”现象，同时不可忽视的是某一频道的传输电平值太高也会引起“鼓包”现象。     

高通滤波器分析及其仿真

分析了THKSS-D型信号与系统实验箱的高通滤波器实验模块,用S平面分析法给出其幅频特性和相频特性,根据通频带定义给出该滤波器截止频率,对有源和无源高通滤波器进行比较,并用Matlab软件对其频率特性进行仿真。     

运算放大器饱和特性对微分电路响应的影响

用运算放大器构造的微分电路可能存在饱和现象,导致输出与输入电压之间不满足微分关系,使微分电路失去应有性能。在应用时应该避免出现饱和现象,在教学中则应使学生理解饱和现象的特点。本文详细分析了在脉冲电压作用下微分电路的输入输出关系,重点是输出饱和时,微分电路模型的建立和分析方法。基于仿真工具和实验手段,对理论分析结果进行了验证。分析内容可以作为电路理论、电子技术、电工学等课程教学内容的扩展。     

开关电源环路中的TL431

虽然上一期文章介绍了如何以TL431实现2类补偿器.然而在补偿电路方面,TL431并非万能药.由于原极点和零点之间以固定系数相关联,采用运放构建的补偿器时,运放的灵活性会降低,而这个运放中可以创建自选的中频带增益.为解决LED串联电阻对可能的增益变化进行钳位的问题,1类补偿器将提供稳定所选转换器时的灵活性,符合期望.然而,这种1类补偿器也有局限,即它不提供任何相位提升.     

采用分割频带法构造宽间隔跳频序列

为增强对偶频带法的保密性,提出了融入随机特性的宽间隔处理新方法——分割频带法。首先对给定的频带进行均匀划分,分割后各区间频带频点相互对应,然后按照随机跳变优先原则或平均间隔优先原则构造区间频带表,以控制跳变规律,实现各频带间的随机转换。分割频带法继承了对偶频带法的核心思想,不改变原始序列的周期长度。理论分析和Matlab仿真结果表明,分割频带法构造的宽间隔序列性能优越,在不恶化序列汉明相关性的前提下,提升了序列保密性和平衡性,可作为宽间隔处理的有效方法。     

ACPM-782犹4：CoolPAM功率放大器

Avago推出两款符合亚洲地区主要移动网络运营商更长通话时间要求，采用第五代CoolPAM技术的新功率放大器产品。支持日本CDMA频带的ACPM-7822以及支持cell-bandCDMA移动通信频带的ACPM-7824通过CoolPAM中的有源旁路功率放大器技术来改善手机的连续通话时间.     

高速高增益运算放大器的设计及应用

本文设计了一种高速高增益放大器,该放大器通过增加全差分的共源共栅电路作为辅助放大器来提高运放增益,并采用频率补偿和钳位管相结合的技术改善运放的频响特性,使得运放在通频带范围内类似于单极点运放,大大减少了运放的转换时间.采用SMIC的0.35μm工艺模型进行仿真,结果表明,运放的直流增益达到110dB,带宽266MHz(负载电容 Cload=1pF),相位裕度55°,只需10ns即可达到0.1%的稳定精度,因而是一种有效的高速高精度运放的实现途径.     

Finite-Impulse-Response Digital Differentiators for Midband Frequencies Based on Maximal Linearity Constraints

Maximally linear digital differentiators (DDs) are known for high accuracy in narrow frequency bands centered at the frequency for which they are designed. In this paper, designs of DDs of odd and even lengths having maximal linearity at the middle of the frequency band are presented. Applying the maximal linearity constraints to the magnitude response of a differentiator gives a system of linear equations, which can be solved for the impulse response coefficients of the differentiator. It is observed that the coefficient matrices of these equations are Vandermonde matrices, and this helps in finding the solution of the equations in closed form. Design examples are presented to show the accuracy of the presented designs, and it is observed that even-length designs are more accurate in a significantly wider frequency band as compared with odd-length designs     

Semistate implementation: Differentiator example

It is shown that the semistate equations can be transformed via a linear transformation into a form which is useful for physical realizations. The result is applied to the example of a semistate described differentiator which is then realized through an op-amp circuit composed of integrators.This research was supported in part by NSF Grant ENG ECS 83-17877.     

A high-swing CMOS telescopic operational amplifier

A high-swing, high-performance CMOS telescopic operational amplifier is described. The high swing of the op-amp is achieved by employing the tail and current source transistors in the deep linear region. The resulting degradation in differential gain, common-mode rejection ratio (CMRR), and other amplifier characteristics are compensated by applying regulated-cascode differential gain enhancement and a replica-tail feedback technique. A prototype of the op-amp has been built in a 0.81-μm CMOS process. Operating from a power supply of 3.3 V, it achieves a differential swing of ±2.15 V, a differential gain of 90 dB, unity-gain frequency of 90 MHz, and >50-dB CMRR. It is shown, analytically and through simulations, that the operational amplifier maintains its high CMRR even at high frequencies     

An Effective Approach to Finding Differentiator Window Functions Based on Sinc Sum Function

An approach to finding digital differentiator window functions is studied. The frequency response of the truncated ideal differentiator is expressed by two parts. One is the ideal frequency response and the other is the deviation on the interval from ω=0 to ω=π. The deviation expression is the sum of weighted functions, where the general expression of these functions is equal to the half-sum of a pair of sinc sum functions plus π, and each weight is a window constant. Using the properties of the sinc sum function eight properties of the general expression and six properties of the deviation expression are deduced. By these properties both the relative errors of the passband and the change of their ripples can be small if each weight is proper and the truncated ideal differentiator is ideal at ω=0. From the expression of the deviation a matrix equation with window constants as unknowns can be written. Examples are given about how to write the matrix equations and how to find the optimized window constants. Four new differentiator windows as a family are obtained. These windows belong to the fixed window. Different from existing windows, the new windows are optimized in terms of reducing the relative errors of the passband. Comparisons show that new windows are better or much better than the Hanning, Hamming, Blackman, Kaiser, Chebyshev and polynomial windows in terms of differentiator performances.     

A 2.5-V, 12-b, 5-MSample/s pipelined CMOS ADC

A set of power minimization techniques is proposed for pipelined ADC's. These techniques include commutating feedback-capacitors, sharing of the op-amp between the adjacent stages of the pipeline, reusing the first stage of the op-amp as comparator pre-amp, and exploiting parasitic capacitors for common-mode feedback. This set of low-power design techniques is incorporated in an experimental chip fabricated in a 1.2-μm, double-poly, double-metal CMOS process. At 12-b 5-Msample/s, the chip dissipates 33 mW of power from a 2.5-V analog supply while achieving a maximum differential nonlinearity (DNL) of -0.78 and +0.63 least-significant bits (LSB) with a peak signal-to-noise ratio (SNR) of 67.6 dB     

一种基于IQP的稳定IIR微分器设计新算法

在分析基于常规QP方法来设计稳定IIR微分器而存在的苛刻的稳定性约束和代价函数不可靠两点不足的基础上，本文提出了一种新的基于IQP的稳定IIR微分器设计算法，本算法应用Rouche定理和有关的收敛准则，解决了稳定性和代价函数存在的问题，从而有效地减少了微分器的设计误差，改善了微分器的性能，使得新的设计方法更加完善、可靠。实例证明了这种设计方法的合理性、可行性，从而为它更加宽广的应用前景奠定了基础。     

运算放大器教学中的若干问题探析

针对电路理论课程中运算放大器（运放）的教学，对教学内容中的若干问题进行了讨论。辨析了不同运放模型符号之间的区别，厘清了虚短和虚断概念并给出了正确表述，说明了含运放电路含“地”的必要性，探讨了对含运放电路分析结果所必须进行得校核，指出了现有运放模型在反映放大倍数频率响应方面的局限性。讨论内容对电路理论课中运放相关教学内容的完善有积极意义。     

基于运放退饱和的电阻炉温度控制系统设计

为了实现电阻炉的快速升温及温度控制,采用运放退饱和的方法,当电阻炉温度未达到设定值时,运放饱和输出,所控制的驱动电路输出脉冲的占空比最大,IGBT近似全导通,电炉加热功率最大,温度快速上升;当温度达到设定值时,运放开始退饱和,输出电压逐渐减小,从而减小驱动电路输出脉冲的占空比,IGBT导通时间变短,电炉加热功率减小,实现温度控制.通过Multisim软件仿真及硬件电路测试,验证了本设计的可行性.该温度控制系统具有升温速度快、易于操作、滞后性较低的优点.     

Adequate SC model of op-amp with finite DC gain and bandwidth suitable for two-op-amp SC biquad analysis

An adequate model of a nonideal op-amp operating in a two-op-amp SC biquad is derived. The model leads to an equivalent SC circuit containing ideal components. Substitution of any op-amp in an SC biquad by its equivalent SC circuit allows the exact frequency response of the biquad to be found easily, taking into account the finite DC gain and bandwidth of op-amps.