You guys may have noticed that recently, I have been showing you a lot of algebraic equations. I really don't like to use, or generate, algebraic equations. Sometimes they're much messier than just ...

Now, we know that I3 = I1 + I2, so V IN must be a nice linear function of V OUT and I1, namely: where F1 and F2 are functions of R1, R2, C1, and C2—and of frequency. We derived that equation just by ...