场效应管, 晶体管, 二极管检波效率比较

70后大叔

实验结果为场效应管检波效率最优, 晶体管次之, 二极管最差，期问把信号改为1mV, 100mV, 500mV, 也没看到场效应管及晶体管波型有失真变型。

wong123

如果条件允许，个人觉得还是通过电路和仪器实验测量数据比较准确，仿真这东西，仅供参考。

3AX12

用二极管的话，BAT85作检波还是不错的。

70后大叔

只想验证下坛上有人说晶体管检波失真的原因   但实验並没有明显失真反映

wong123

曾经做过试验，几个厂家提供的透明状红色LED，有高亮、普亮，在5mA、10mA、20mA电流时测试，先不说亮度差异之大，压降从1.7V-2.1V都有。有的高亮LED从100微安工作电流开始有微红光，0.5mA时都相当亮度了，有些普亮需要差不多1mA时才能见到红光，这只是常规同类型元件的差别。
不同厂家不同批次都有区别，仿真时采用什么数据才准确，所以仿真还是有一定局限性的。

大孔景元

早先制作一款电缆故障探查仪器，需要能精细指示信号电平的电路，固定512赫兹频率，理所当然用了运放带捅放大，运放性检波，表头是标准对数刻度，最后用信号发生器的衰减刻度校准时发现读数严重偏离，基本无法使用。后来索性简化电路，用谐振放大器放大，其实就是收音机中放电路，只是把中周改成音频变压器，用简单的二极管检波，再用信号发生器校对时发现刻度一一对应丝毫不差。
说二极管检波失真的或多或少都有些想当然，中周的Q值随检波管的工作状态而变化，小信号时假使二极管不导通，中周无负载，Q值增高、谐振电压增高以维持检波输出，加上调幅广播的调制度一般小于30%，二极管的非线性是完全不需要考虑的

70后大叔

大孔景元 发表于 2016-8-23 23:02
早先制作一款电缆故障探查仪器，需要能精细指示信号电平的电路，固定512赫兹频率，理所当然用了运放带捅放大 ...

二极管检波失真应该锗管会明显点  
现在的硅管曲线很斜  只有很小的一段在非线性

园丁

70后大叔 发表于 2016-8-24 01:13
二极管检波失真应该锗管会明显点  
现在的硅管曲线很斜  只有很小的一段在非线性

检波失真不仅仅只和非线性有关，相同的材料也有不同的特性，不同的材料之间也存在着差别。

e3po

        用运放做精密检波吧

e3po

wong123 发表于 2016-8-23 04:36
曾经做过试验，几个厂家提供的透明状红色LED，有高亮、普亮，在5mA、10mA、20mA电流时测试，先不说亮度差异 ...

光是辐射的一种， 辐射不包含在 SPICE 里面。 那是国家机密。


SPICE was developed at the Electronics Research Laboratory of the University of California, Berkeley by Laurence Nagel with direction from his research advisor, Prof. Donald Pederson. SPICE1 was largely a derivative of the CANCER program,[4] which Nagel had worked on under Prof. Ronald Rohrer. CANCER was an acronym for "Computer Analysis of Nonlinear Circuits, Excluding Radiation," a hint to Berkeley's liberalism in the 1960s:[5] at these times many circuit simulators were developed under the United States Department of Defense contracts that required the capability to evaluate the radiation hardness of a circuit. When Nagel's original advisor, Prof. Rohrer, left Berkeley, Prof. Pederson became his advisor. Pederson insisted that CANCER, a proprietary program, be rewritten enough that restrictions could be removed and the program could be put in the public domain.[6]
SPICE1 was first presented at a conference in 1973.[7] SPICE1 was coded in FORTRAN and used nodal analysis to construct the circuit equations. Nodal analysis has limitations in representing inductors, floating voltage sources and the various forms of controlled sources. SPICE1 had relatively few circuit elements available and used a fixed-timestep transient analysis. The real popularity of SPICE started with SPICE2[8] in 1975. SPICE2, also coded in FORTRAN, was a much-improved program with more circuit elements, variable timestep transient analysis using either the trapezoidal (second order Adams-Moulton method) or the Gear integration method (also known as BDF), equation formulation via modified nodal analysis[9] (avoiding the limitations of nodal analysis), and an innovative FORTRAN-based memory allocation system developed by another graduate student, Ellis Cohen. The last FORTRAN version of SPICE was 2G.6 in 1983. SPICE3[10] was developed by Thomas Quarles (with A. Richard Newton as advisor) in 1989. It is written in C, uses the same netlist syntax, and added X Window System plotting.
As an early public domain software program with source code available,[11] SPICE was widely distributed and used. Its ubiquity became such that "to SPICE a circuit" remains synonymous with circuit simulation.[12] SPICE source code was from the beginning distributed by UC Berkeley for a nominal charge (to cover the cost of magnetic tape). The license originally included distribution restrictions for countries not considered friendly to the USA, but the source code is currently covered by the BSD license.

70后大叔

e3po 发表于 2016-8-24 08:10
用运放做精密检波吧

这个成本太高, 高頻的运放很貴的.

60年代的爱好者

各种二极管的性能差别很大，以什么特性做仿真是个很大的问题，所以这个仿真不靠谱。

e3po

大孔景元 发表于 2016-8-23 07:02
早先制作一款电缆故障探查仪器，需要能精细指示信号电平的电路，固定512赫兹频率，理所当然用了运放带捅放大 ...

     还有一个要点是调制的时候就带了直流偏移的。