
186 Gallium Nitride (GaN): Physics, Devices, and Technology
transceivers [186]. The realization of the class-S concept including the complex
ltering aspect is given in the study of Leberer et al. [180]. The class-S amplier
requires a broadband digital signal to be an amplier with an oversampling of at
least 4:1 of the equivalent analogue center frequency. For example, a center fre-
quency of 450 MHz relates to a digital bandwidth of 1.8 Gbit/s. Examples of GaN
core chips for high frequencies for advanced class-S MMICs operation are pre-
sented in the study of Maroldt et al. [38]. They are based on gate lengths of 0.5 μm,
and, especially, 0.25 ...