电子线路学习方法(十三) 第五讲 三极管电路分析方法(下)

<正> 六、单级放大器交流电路分析方法和思路培养三极管交流工作状态是指放大信号的过程,三极管单级放大器是电路中最小的放大单元电路,它能够独立地完成对信号的放大任务,通常单级放大器电路中只使用一只三极管。一个放大系统由许多单级放大器构成,所以掌握单级放大器电路的工作原理是分析多级放大器的基础。 1、了解三种类型三极管放大器放大特性无论三极管单级放大器的具体电路形式如何变化,三极管只能构成三种独立类型的单级放大器,表2是三极管三种类型放大器特性,了解它们的特性有利于对电路工作原理的分析。 2、放大器类型判别思路和方法     

12SN7两管立体声前置放大器制作

前置放大器的增益要求不高,因此 总是采用三极管作放大级,这样有利于降低噪声、减小失真和简化电路。这次我们介绍每个声道各用一只双三极管组成的前置放大器,与上次的三极管单管放大相比,多用了一个三极管,因此有可能通过电路设计来实施性能的改善。 一、电路简介 图1为本机一个声道的原理图。大致可以看出,每个声道仍用单级放大的程式。但由于使用了一个双三极管,采     

神通广大的晶体三极管

晶体三极管简称晶体管或三极管,是一种具有两个PN结的半导体器件。晶体三极管的最大特点是具有电流放大及控制作用,它是在电子线路中被广泛使用的重要电流控制型器件。利用晶体三极管的特性,可以组成放大、振荡、开关等各种功能的电子电路。     

用具有真空三极管特性的半导体器件制作的35W单声道功率放大器

TKS45F323是日本NEC Talkin生产的具有真空三极管特性的半导体SIT,本文介绍的是一款注重音质的、采用类似真空管放大电路的音频功率放大器。在电路设计时,为了避免放大级供电电路引起的相位失真,在电压放大级采用了由FET和稳压二极管组成的简单的恒压、恒流电源。并通过对频率特性和群延时特性的仿真,确定输出级的栅极电阻和输入电阻,获得平坦的特性和良好的音质。放大器的频率     

用具有真空三级管特性的半导体器件制作的35W单声道功率放大器

TKS45F323是日本NEC Talkin生产的具有真空三极管特性的半导体SIT,本文介绍的是一款注重音质的、采用类似真空管放大电路的音频功率放大器.在电路设计时,为了避免放大级供电电路引起的相位失真,在电压放大级采用了由FET和稳压二极管组成的简单的恒压、恒流电源.并通过对频率特性和群延时特性的仿真,确定输出级的栅极电阻和输入电阻,获得平坦的特性和良好的音质.放大器的频率特性一直延伸至250kHz.     

简易电路特性测试仪的设计

本文主要叙述了以2019年全国大学生电子设计竞赛D题为原型的一种以STM32单片机为主控芯片的简易电路特性测试仪方案,通过单片机采集三极管放大电路的电压,计算输入阻抗,输出阻抗,增益,使用器件简单常见,成本低廉,该电路特性测试仪能自动测量并显示放大电路的输入、输出电阻、增益,显示上限频率值和幅频特性曲线,判断电路的故障,是理想的电路检测装置。     

50W×2半导体无反馈功率放大器

大环路负反馈可以减小失真、降低输出阻抗,可以扩展放大器的频带宽度,但同时也存在有负面影响,可以说有利也有弊。本文介绍的放大器不采用大环路负反馈,为了减小各种调制失真,电路的输入级和第二级分别采用场效应管和双极型晶体三极管构成对称式的两级放大电路,输出级用双极型晶体三极管做达林顿连接构成SEPP输出级。电路简单、失真小。同时,为了防止输出器件和扬声器遭受破坏,在电路中加入了偏压上限限制电路、输出器件电流限制电路和扬声器保护电路。     

L6GC推挽功率放大器

本文介绍一款用三极五极复合管6AN8和6L6GC构成的推挽功率放大器。作为电压放大级，三极五极复合管的组合方式有多种，本文就用6AN8组成的两种SRPP电路与五极管作共阴放大三极管作阴极输出器的电路进行了实测比较，得出阴极输出器的方案在增益、失真率、最大输出和输出阻抗等方面均较两种SRPP电路优越。因此该功率放大器的电压放大级采用五极管差动放大电路和三极管阴极输出器电路组成，     

胆机和电子管的基础知识（五）

在前面基础知识的基础上,要设计或制作一个电压放大级,最基本的选择就是所用电子管的选择,究竟是采用五极管还是采用三极管好呢？这完全要看电路的用途和电路的特性来定,如果电压放大级所要求的放大倍数较高,同时或者功率级所需要的驱动电压相当高,那么通常的情况下可以利用一个五极管作为电压放大来完成任务,或者利用两级三极管进行放大;如果电压放大级所要求的输出电压不是太高,或者功率管不需要太大的输入动态,那么应用普通的三极管作为电压放大级即可。这一点想必不需要详细说明,仅看自已的需要而定,不过应用五极管电路或三极管电路作放大时,要理解采用不同结构的管子作电压放大管时,五极管和三极管之间的应用区别和它们不同的一些物理特性。     

三极管放大了什么？

前不久有初学者问我关于三极管放大电路的问题。他认为根本不需要三极管放大电压、只需要在输出端直接给一个比较大的电压就行了。其实这是他对三极管放大的认识不够清楚。三极管放大电路的目的不是为了提高电压,电压升压是DC—DC电路模块的功能。三极管放大电路的功能是放大信号,信号是指电压波动的幅度。把小的波动幅度,变成较大的。例如,说话的声音波动幅度和“力量”较小,但在KTV的大音箱中播放出来,波动幅度很大,音量更大。理解了三极管放大的原理和意义,才能真正明白模拟电路。     

New four-quadrant CMOS analogue multiplier

The letter describes a new four-quadrant CMOS analogue multiplier with a simple circuit configuration. This multiplier is based on the current/voltage characteristics of MOS transistors operating in the triode region. The simulation result shows less than 1% distortion for both input signals of 4Vpp when supply voltages of ± 5V are used.     

调制型半导体激光器驱动电路设计

半导体激光器以体积小、质量轻、驱动功率和电流较低、效率高、工作寿命长、可直接调制、易于与各种光电子器件实现光电子集成及与半导体制造技术兼容、可大批量生产等特点得到了广泛的研究与应用,研究和改进激光器驱动电路具有重要的意义。小功率可调谐半导体激光器对驱动电流有很高的要求,驱动电流的微小变化将直接导致其输出光强的波动。为实现半导体激光器的稳定功率输出,基于电流负反馈原理设计包含慢启动和限流保护电路的恒流驱动电路。在电路设计中尽可能利用简单的器件和设计起到改善激光器正常工作的目的。在调制过程中分别利用运放与三极管的不同特性设计出了低频低失真和高频开关调制电路。利用两级放大负反馈原理进行反馈电流的调整,降低闭环带宽,增强了闭环负反馈的稳定性。     

An Efficient Macromodeling Approach for Simulating Carbon-Nanotube Field-Emission Triode Devices in Display Applications

The advances of using carbon-nanotube (CNT) triode structure field-emission (FE) devices for display applications require an accurate and efficient SPICE-compatible device model for evaluating their electrical behaviors in the early circuit and system design stage. This letter presents a simple and efficient macromodeling approach that can accurately model the CNT triode FE devices independent of the device process and physical structures for circuit simulations.     

A dual differential charge-coupled analog delay device

A dual differential charge-coupled analog device providing signal delays of 24 and 48 elements has been designed for sampled data analog signal processing applications. The aim of this design was to eliminate some of the disadvantages that have been associated with previous charge-coupled devices (CCD's). These include clock pickup, thermally generated dc offsets, and complex external control and amplification circuitry. The device has an input strobing circuit and an on-chip output amplifier. With a clock frequency of 8 kHz and a 400-mV rms input signal, the total harmonic distortion was below 0.2 percent and the signal-to-noise ratio was better than 70 dB with a 4-kHz bandwidth. The device gain was 6 dB and a gain variation of 0.2 dB was observed over a temperature range of 0 to 55°C.     

Third-Order Intermodulation Distortion and Gain Compression in GaAs Fet's

A simple unilateral nonlinear circuit model of a GaAs FET is used in the analysis of the third-order intermodulation distortion and gain compression characteristics of a single-stage amplifier. Expressions are obtained for these characteristics, relating them to the input power level and to the device load admittance. The expressions are illustrated with contours on the load admittance plane of constant intermodulation distortion ratio, intercept point gain compression, AM-to-PM conversion, and output power, and as output power versus input power plots for fixed terminations. Agreement with experimentally measured distortion characteristics is good.     

Low–frequency circuit theory of the double–base diode

The double-base diode is a single-junction semiconductor triode. When an electric potential is applied between the two ohmic contacts, a negative-resistance is obtained between the junction and one of the ohmic contacts. This negative resistance is bounded by two positive-resistance regions, one of considerably high magnitude which corresponds to the cut-off state and one of very low magnitude which corresponds to a saturating condition. The magnitude of the negative resistance is related to the ratio of majority-to-minority carrier mobilities. Small-signal low-frequency equivalent circuits are developed to approximate the double-base diode in each of the operating regions of the negative-resistance characteristic and equations for current and voltage amplification, input and output resistance and power gain are developed. The important circuit parameters are related to the physical constants of the device.     

A dual differential charge-coupled analog delay device

A dual differential charge-coupled analog device providing signal delays of 24 and 48 elements has been designed for sampled data analog signal processing applications. The aim of this design was to eliminate some of the disadvantages that have been associated with previous charge-coupled devices (CCD's). These include clock pickup, thermally generated d.c. offsets, and complex external control and amplification circuitry. The device has an input strobing circuit and an on-chip output amplifier. With a clock frequency of 8 kHz and a 400-mV r.m.s. input signal, the total harmonic distortion was below 0.2 percent and the signal-to-noise ratio was better than 70 dB with a 4-kHz bandwidth. The device gain was 6 dB and a gain variation of 0.2 dB was observed over a temperature range of 0 to 55/spl deg/C.     

Intermodulation Distortion in CMOS Attenuators and Switches

Gain control elements are widely used in communication systems both to limit the incident power to the circuitry and to control the amplitude of the transmitted signal. Attenuators are one way of controlling the signal amplitude. The distortion performance of common CMOS attenuator topologies is investigated in this work. CMOS device equations that model the device in different regions of operation and which also model short channel effects are used for calculating distortion performance. Calculated distortion is compared with simulation results and experimental data, and qualitative explanations of the distortion curves as well as the deviation between different sources of data are given. Potential improvements in linearity performance of attenuators via circuit design techniques have also been discussed     

Characteristics of the dielectric diode and triode at very high frequencies

The dielectric triode is represented as a one-dimensional parallel-plane model, where the gate electrode consists of a thin continuous equipotential sheet of charge (as in the triode proposed by G.T. W ). Such a triode is the solid-state analogue of the vacuum pentode with high input and output impedance and operating under conditions of space-charge-limited current.

The incremental admittance and transadmittance of the dielectric triode are calculated as functions of transit angle, current density, geometrical dimensions and properties of the material used.

The triode in the small-signal mode of operation is represented as a linear active two-port circuit element. The four basic Y parameters of this element are calculated.

It is shown, that the dielectric triode can operate as a conventional wide-band amplifier up to frequencies of many thousands of megacycles. It is shown also, that electronic processes inside the triode do not set the limit for device operation at the frequencies corresponding to the transit angles much larger than π, and the triode can operate at these frequencies as a tuned amplifier, with the effect of “cold” interelectrode capacitances eliminated.

It is concluded, that the dielectric triode should considerably extend the u.h.f. limit of operation of transistors and conventional vacuum tubes.     

高保真音频功放器设计

针对高品质音频的需求,设计了一种高保真音频放大器。该音频放大器主要由信号放大电路、功率放大电路和有源滤波电路组成,其中信号放大部分采用场效应管及运算放大器。其受外界的干扰性较小,稳定性较高,放大倍数可达到20～30倍,随需要而进行调节。功放部分采用LM4766型芯片,采用差动放大电路对信号实现音频信号的放大,失真小于百分之零点一。滤波电路采用了二阶有源低通滤波电路,对输入的音频信号进行处理。该设计的音频功率放大器具有失真度小、增益可调、体积小等特点,具有较高的实用价值。