Gate drive circuit with feedback-controlled active resistance

An active resistance is controlled to modify a drive signal provided to a gated device such as an insulated gate bipolar transistor (IGBT). The active resistance is between an input lead that receives an input drive signal, such as from a conventional gate driver IC, and an output lead at which an output drive signal is provided to the device's gate. The active resistance is controlled in response to a feedback signal that includes information about the output drive signal, so that the output drive signal is a modified version of the input drive signal. To reduce di/dt and hence control EMI emission, the output drive signal can include turn-on and turn-off transitions where the input drive signal includes steps. A transition can, for example, include an interval during which the active resistance is greater than zero to reduce peak voltage, another interval during which the active resistance is approximately zero to allow a large gate current, and yet another interval during which the active ...