Envelope Tracking or Polar—Which Is It? [Microwave Bytes]

The terms “envelope tracking” (ET), “evelope elimination and restoration” (EER), and “polar” are generally used interchangeably in the literature for any transmitter circuit built using a dynamic power supply (DPS) architecture on the RF power amplifier (PA). Indeed, these are sometimes combined together into the same category and called EER/ET or ET/EER [1]. It is my experience from more than 15 years working with these technologies that there are very distinct and major differences between these techniques. Establishing simple and clear definitions as to which is which helps us clearly understand the differences between them. More importantly, this allows much less ambiguity as the literature expands regarding these important transmitter techniques.