Enabling the Internet of Things: Reconfigurable power amplifier techniques using intelligent algorithms and the smith tube

Future Internet of Things (IoT) devices will need to maintain high power efficiency while being able to reconfigure for changing performance requirements and operating frequencies. The design of quickly reconfigurable power amplifiers able to maintain high efficiency and meet spectral requirements will be critical to success. This paper discusses fast optimization techniques that will be useful in real-time optimization of transmitter power amplifiers: (1) a vector-based algorithm to find the load impedance giving the highest power-added efficiency (PAE) while keeping the adjacent-channel power ratio (ACPR) below a prespecified minimum, (2) the use of a spectral mask directly in the load-pull optimization in place of the ACPR, and (3) the extension of the Smith Chart to a three-dimensional, cylindrical “Smith Tube” for optimization involving an additional parameter: the waveform bandwidth. This paper builds a framework for design and the real-time optimization of reconfigurable, efficient, and spectrally compliant IoT power amplifiers.