On Thu, 7 Aug 2003 16:42:13 -0400, "John Walton"
wrote:

I can use the Bode Plotter in multisim, nice imaginary tool ! Now, the
question is -- how do I replicate a bode plotter for phase measurement in a
regulated power supply -- I have read the Tektronix MBD, and do have access
to a pulse generator and scope with FFT.


Middlebrook's classic paper Measurement of Loop Gain in Feedback
Systems, International J. of Electronics, vol. 38, no. 1, pp. 485-512,
April 1975. IJE addresses this exactly.

If you do a Google search using Middlebrook Loop Gain you will find a
lot of discussion on how to do it in practice. One I found quickly
was http://www.venable.biz/tp-18.pdf which discusses measuring loop
gain/phase in a power supply via injecting a low level AC signal into
the feedback loop.

Jack