EE 214 Lecture 15 (HO#21)B. Murmann2Overview•Introduction–Last lecture, we've seen that return ratio analysis is a useful tool for characterizing feedback amplifiers in terms of stability, bandwidth and static precision. Since we are always interested in verifying our hand analysis results using simulations, it is desirable to have an equivalent method available in Spice. In this lecture, we will discuss the so called Middlebrook method for loop gain simulation. This particular approach helps overcome the issue that ideal loop breakpoints, e.g. at controlled sources, are not directly accessible in Spice.