Circuits and methods for gate overdrive in gan power stages

A power converter system comprising:

• a gallium nitride (GaN) power switch having a gate terminal, a drain terminal, and a source terminal;
• a variable voltage driver circuit coupled to the gate terminal and arranged to provide a gate drive voltage to control the GaN power switch;
• a drain voltage detector circuit coupled to the drain terminal and arranged to detect when a drain terminal voltage exceeds a predetermined threshold;
• wherein the variable voltage driver circuit is arranged to:
• increase the gate drive voltage from a first voltage level to a second voltage level when the drain terminal voltage exceeds the predetermined threshold;
• maintain the second voltage level for a predetermined time period;
• and
• reduce the gate drive voltage to zero when the drain terminal voltage exceeds the predetermined threshold during the predetermined time period.

A driver circuit for controlling a gallium nitride (GaN) power switch, the driver circuit comprising:

• an output terminal arranged to be coupled to a gate terminal of the GaN power switch;
• a voltage generation circuit arranged to generate a first gate drive voltage and a second gate drive voltage, wherein the second gate drive voltage is greater than the first gate drive voltage;
• a detector input terminal arranged to receive a drain voltage signal from a drain terminal of the GaN power switch;
• a switching circuit coupled between the voltage generation circuit and the output terminal;
• and
• control logic arranged to:
• control the switching circuit to provide the first gate drive voltage to the output terminal during normal operation of the GaN power switch;
• and
• control the switching circuit to provide the second gate drive voltage to the output terminal when the drain voltage signal indicates the drain terminal voltage exceeds a predetermined threshold.