A simple method to calculate power amplifier efficiency versus output powerproduct forum A simple method to calculate power amplifier efficiency versus output power Looking for a new method to save valuable design time? This new method allows the designer to evaluate a PA’s efficiency without actual buildup. By Frank Della Corte transistors. Although not necessary for this discussion, a PA designer needs to consider the optimal operating point for the PA transistor to obtain maximum efficiency. For Class-AB mode, the PA’s output power capability versus its load line (Rlcap) is given by the following relationship: Pcap = (Veff)2/2Rlcap, Where Veff = Vcc-Vsat Once the load line is set, the maximum power transfer, hence maximum PA efficiency, will occur when the load is equal to the load line. The typical load lines for 3-volt PAs run on the order of 2 to 5 . In pra……