运算放大器基本介绍（中国大陆）National Semiconductor

简介：这次研讨会为需要使用运算放大器的工程师提供一个数据详尽的“速成课程”,重点介绍运算放大器的基本运作原理和电路设计的问题以及运算放大器的应用.

问：If NSC has CMOS technology AMP?
答： Yes, our LMC op amp series are all CMOS op amps.

问：请专家介绍一下：
    在电路设计时使用运算放大器，基本的原则是什么？需要注意纳方面的问题？

答： Just brifely.
Power supply range.
Input range.
Output range.
Gain of the amplication
Output loading
If RRIO is needed?
enough GBWP to cover whole freq range...

问：請問如何有效的實際測量op的特性
答： All of the IC from our company are tested before we ship out. Basically, datasheet/spec is a very good reference for device performance. The actual measurement can be done by customer depends on the actual configuration. In general, I will suggest to use a

问：WEBENCH软件是否免费？
答： Yes, it is absolutely free of charge. Feel free to use it.

问：用webench模拟出来的结果与实际硬件电路会有多大的差异呢？
答： It depends on the design of your other system such as power supply. In gerenal, the webench simulation can reach 90% accuracy to actual result.

问：运放的输出短路保护能力如何?在设计上如何考虑过载能力?
答： Usually, there is current limitor circuitry inside the opamp in order to protect the IC. However, in case of safety, please refer to datasheet / specification for max value.

问：运算放大器的负载能力与哪些因素有关？如何提高运算放大器的负载能力？
答： The output capability of an op amp depends on the output stage circuit design. In case you really need to drive a heavy load, we recommend that you should use an external transistor.

问：对于抑制高次谐波，差分放大与单端放大那个好？
答： It depends if your system is signal supply or dual supply with negative supply. Also, how you design the ground & power make big difference. Usually, I like diff amp 差分 better.

问：放大器设计工具对元件的分布参数/寄生参数有何考虑?
答： These data is not included in this webench tool because parasitic parameters always releated to your pcb material...number of layer, trace width, etc. These uncertain is not completed..also not important for you to start design at the very beginning stage.

问：双极运放和CMOS运放在性能有何差别?
答： Biploar op amp usually has a lower input impedance and high input bias current, high current noise, also has a faster speed.

CMOS op amp usually has a higher input impedance and lower input bias current, high voltage noise, lower speed (BW) but co