A display device backlight comprises at least one LED and a control circuit for controlling the brightness of the LED, wherein the control circuit comprises a drive transistor for driving a current through the LED and a pulse width modulation circuit for controlling the timing of operation of the drive transistor. A compensation circuit provides a first boost current to the gate of the drive transistor during a rising edge of the current profile and provides a second boost current to the gate of the drive transistor during a falling edge of the current profile. This arrangement improves the switching response of the drive transistor by providing boost currents to/from the gate of the drive transistor during the rising and falling edges of the current through the drive transistor (in response to steps in the PWM control signal).