TINA-TI 9.1 is a powerful SPICE-based analog design and simulation tool. The latest version of the free software program, which averages 5X speed increases over version 7.0, allows engineers to design, test and troubleshoot a broad variety of basic and advanced analog circuits, including complex architectures, without any node or number of device limitations.
http://focus.ti.com/docs/toolsw/fol...id_pod1=MjIyMDQ3MzIwODcS1&sp_mid_pod1=3441873
http://focus.ti.com/docs/toolsw/fol...id_pod1=MjIyMDQ3MzIwODcS1&sp_mid_pod1=3441873