High-Efficiency Low-Complexity ASK Transmitter Using an Inverse Class-F Power Amplifier with a Nonuniform Transmission-Line-Based Load Transformation Network

High-efficiency low-complexity transmitters are needed to connect an increasing amount of devices to our wireless networks. We present an amplitude-shift-keying transmitter (Tx) that utilises an inverse class-F power amplifier (PA) in combination with a discrete supply modulator controlled by a microcontroller to achieve above 50% average drain and power added efficiency (PAE) of the overall Tx at 33.9 dBm average output power. The inverse class-F PA is designed using a nonuniform transmission line (NUTL) as load transformation network (LTN), which enables 69.9% average PAE over a broad drain supply voltage range from 18 V to 38 V. A design methodology for a switch-mode PA utilising a NUTL as LTN is proposed, furthermore.