A novel efficiency‐enhancement topology: GaN high‐electron mobility transistors with waveform‐modulation structure composed of Schottky diodes

To improve the power‐added efficiency (PAE) of the gallium nitride (GaN) high‐electron mobility transistor (HEMT) in radio frequency applications, this paper studies the relationship between the nonlinearity of the gate capacitance and the PAE of the GaN HEMTs. The theoretical analysis and simulation results demonstrate that the nonlinearity of the gate capacitance modulates the signal phase at the GaN HEMT input and increases the average drain current, leading to increased power consumption and reduced PAE. Then, an efficiency‐enhancement topology for GaN HEMTs that employs the waveform‐modulation effect of Schottky diodes to reduce power consumption and improve efficiency is presented. The efficiency‐enhancement topology for a 4 × 100‐μm GaN HEMT with waveform‐modulation diodes is then fabricated. Results of load‐pull test demonstrate that the novel topology can increase the PAE of the 4 × 100‐μm GaN HEMT by more than 5% at 8 GHz. The novel efficiency‐enhancement topology for GaN HEMTs proposed in this paper will be suitable for applications that demand high‐efficiency GaN HEMTs or circuits.