A New Adaptive Delay Method for Wideband Kahn's RF Power Amplifiers

This paper presents an adaptive delay control method used in wideband Kahn's envelope elimination and restoration (EER) RF power amplifiers (PAs). Besides control circuits, envelope and phase signals are also implemented by baseband digital signal processing (DSP) technique. It avoids using not only nonlinear limiter and envelope detector, but also difficult RF delay module or complicated feedback loop, each of which is necessary in conventional EER PA's structure. With the help of applying phase detector, counter, and latch register, the delay varies adaptively with circuit parameters, and then the new PA maintains performance at all times. With the application of this method we can realize a PA applicable to IEEE 802.11b standard with 11MHz signal bandwidth, of which adjacent channel power ratio (ACPR) is better than -40dBc at the first side lobe.