Multiplication and Logarithmic Conversion by Operational Amplifier‐Transistor Circuits
Multiplication and Logarithmic Conversion by Operational Amplifier‐Transistor Circuits
复制标题
运算放大器-晶体管电路的乘法和对数转换
DOI：
10.1063/1.1718225
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发表时间：
1963
期刊：
影响因子：
--
通讯作者：
William L. Paterson
中科院分区：
文献类型：
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作者：
William L. Paterson
文献中基于结型二极管的乘法器和对数转换器电路的共同要求是所采用的结具有对数I对V特性的恒定斜率。当考虑Cutler‐Bath和Sah‐Noyce‐Shockley类型的电流分量时，发现任何一个分量成为主导的范围，允许应用结进行对数转换，是狭窄的。硅扩散晶体管的传输电导yFB显示出所需的对数特性在几十年。使用一个运算放大器施加所需的偏置条件进行了讨论，连同由放大器施加的性能限制。给出电路说明该技术的应用真空计，晶体管测试，并模拟乘法器具有五十年的动态输出范围。商用静电计只需两个分量相加就可转换成对数指示。
Multiplier and log converter circuits in the literature which are based on junction diodes have in common the requirement that the junction employed have a constant slope of the log I vs V characteristic. When current components of the Cutler‐Bath and Sah‐Noyce‐Shockley types are considered, it is found that the range over which any one component becomes dominant, permitting application of the junction for logarithmic conversion, is narrow. The transfer conductance yFB of silicon diffused transistors is shown to exhibit the desired logarithmic characteristic over many decades. The use of an operational amplifier to impose the required bias conditions is discussed, together with performance limitations imposed by the amplifier. Circuits are given illustrating the application of the technique to vacuum gauges, transistor testing, and to an analog multiplier having a dynamic output range of five decades. A commercial electrometer is converted to logarithmic indication by the addition of only two components.