Section 5, Two-Quad, #5) Why must the conversion gain be calculated with RMS voltages, and how do I go about finding them?
Since conversion gain deals with power efficiency, the ratio is really that of (Power Out)/(Power In), or (Useful Signal Out)/(Useful Signal In). However, remembering that P = (Vrms)2/Z, and assuming the impedances are the same, we can compare a ratio of voltages to get the effective ratio. But since we’re dealing with power, that means the ratio is of (Vrms)2. Keep in mind that ADS’s fs(…) function gives voltage amplitude, so you must convert that to RMS. Also remember that since you need to include both sidebands, you must add both sidebands’ powers, not their RMS voltages nor their amplitudes. Thus, the answer comes out to look something like this: The definition of RMS, or “Root Mean Square,” can be found here for a quick refresher.
