High frequency GaN FET applications can take advantage of switching transition speeds in the sub nano-second range using Efficient Power Conversion Corporation new third generation devices. Among the applications that require this speed are envelope tracking in RF power amplifiers and highly resonant wireless power transfer systems for wireless charging of mobile devices.





Before describing these two applications here are details of the new GaN FETs. They have features that enable higher speed designs, including:

·     Reduction in QGD, which reduces voltage transient switching losses

·     Improved Miller ratio that provides high dv/dt immunity

·     Low inductance pads provide improved connection to both gate and drain circuits

·     Orthogonal current flow between the gate and drain circuits permit enhanced common source inductance (CSI) reduction

·     Separate gate return connection also enables enhanced CSI reduction.

Table 1 lists the characteristics of this EPC8000 family.

Envelope tracking is an RF design approach in which the power amplifier constantly adjusts its applied power supply voltage to ensure it is operating at peak efficiency for its instantaneous output power requirements. Without envelope tracking, amplifiers operating with a constant supply voltage become less efficient as the signals crest factor increases, because the amplifier spends more time operating below peak power and, therefore, spends more time operating below its maximum efficiency.