A 13.56 MHz high-efficiency current mode class-D amplifier using a transmission-line transformer and harmonic filter

This paper presents a high-efficiency current mode class-D (CMCD) amplifier using a Guanella´s 1:1 transmission-line transformer and a harmonic filtering technique. Low second and third harmonic levels are achieved by the harmonic filtering technique used in the output matching network. The implemented CMCD amplifier exhibited a power gain of 13.4 dB and a high PAE of 84.6 % at an output power of 44.4 dBm using a 13.56 MHz input CW signal. The second and third harmonic distortion levels were measured at -50.3 dBc and -46.5 dBc, respectively, at the same power level.