目前常用的电路仿真软件有Multisim、LTspice IV、Ti-Tina， 其中后两种可以免费下载使用，它们各有自己特点，现在另外一种商用电路仿真软件Micro-Cap 12也提供免费下载使用。
http://www.spectrum-soft.com/download/download.shtm
它不但包含了丰富的器件库，提供常规的瞬态分析，直流分析和交流分析等等，它还有一些自己的新特性。
参数扫描
设置选定参数扫描步进， 可以把它对系统的影响直接显示结果中，方便用户评估参数对系统的影响。
滤波器设计
它包含了有源和无源滤波器的辅助设计，只有给的滤波器的种类，增益，带宽，截止频率以及纹波要求等等，它直接输出原理图和器件参数。
有源滤波
无源滤波
News:
Effective 7/4/2019, Spectrum Software is closed. Micro-Cap is now free.
Technical support will be available for at least 90 days via email at Support.
You can download the latest versions of Micro-Cap here: Download
You can choose either the executable program or the entire installation CD for MC10, MC11, and MC12. If you have an earlier version, download and use MC12. These new versions do not require the security key, so they make Micro-Cap free to the entire engineering community.
Thank you for the honor and privilege of serving you for the last 39 years.
Spectrum Software