Transistor turn-off circuit

A method of operating a circuit, the method comprising:

• providing a power transistor with a gate terminal, a source terminal and a drain terminal, the gate terminal arranged to control operation of the power transistor;
• providing a control circuit coupled to the gate terminal and arranged to change a conductivity state of the power transistor;
• and
• receiving, control circuit, a turn-off signal, wherein in response to receiving the turn-off signal the control circuit controls a voltage at the gate terminal such that the voltage at the gate terminal changes at a first rate of voltage with respect to time from a first voltage to a first intermediate voltage, and at a second rate of voltage with respect to time from the first intermediate voltage to a second intermediate voltage, and at a third rate of voltage with respect to time from the second intermediate voltage to second voltage.

A power converter circuit comprising:

• a power transistor with a gate terminal, a drain terminal and source terminal, the gate terminal arranged to control operation of the power transistor, and the drain terminal coupled to a first node of a first winding of a primary side of a transformer;
• a control circuit coupled to a first node of a second winding of the primary side of the transformer and coupled to the gate terminal;
• and
• wherein the control circuit is arranged to change a voltage at the gate terminal at a first rate of voltage with respect to time from a first voltage to a first intermediate voltage, and to change the voltage at the gate terminal at a second rate of voltage with respect to time from the first intermediate voltage to a second intermediate voltage, and to change the voltage at the gate terminal at a third rate of voltage with respect to time from the second intermediate voltage to a second voltage.