The operating principles and architecture of a Chireix power amplifier implemented in Class-E switching mode for multistandard radio transmitters are considered. Its basic structure is described, including transistor stages, broadband matching networks, and a Marchand transformer used as a broadband combiner. Reconfiguration options of the Chireix scheme with separate or joint design of the amplifier block and the combiner are presented, taking into account the influence of parasitic elements. Methods for controlling reactive elements (varactors and capacitor banks) are discussed. The operation of the Chireix amplifier under load modulation is analyzed, demonstrating the ability to maintain high efficiency over a wide range of output power levels, including reduced-power modes. It is shown that when the signal frequency changes, the high efficiency of the Chireix scheme can be preserved without retuning its circuits by adjusting the operating mode of Class-E amplifiers. Calculations confirm that the average efficiency of this scheme can reach up to 95% at a peak-to-average power ratio of 12–14 dB.