| 摘要 |
A gate drive circuit (10a) to drive a gate terminal (G) of a power transistor (12a). The gate drive circuit (10a) includes a first capacitor (C1), a first switch (SW1), a measurement circuit (5) and a reference source (6) to generate a reference voltage (Vref). The first capacitor (C1) has a first terminal (T11) electrically coupled to the gate terminal (G) of the power transistor (12a). The first switch (SW1) is arranged between a second terminal (T21) of the first capacitor (C1) and a first predetermined voltage (Vp1). The measurement circuit (5) is used to measure a differential voltage across the first capacitor (C1). The gate drive circuit (10a) is configured to pre-charge the first capacitor (C1) to obtain a second predetermined voltage (Vp2) across the first capacitor (C1). The gate drive circuit (10a) is further configured to arrange the first switch (SW1) in an on state to turn on the power transistor (12a) and to electrically couple the first predetermined voltage (Vp1) to the second terminal (T21) of the first capacitor (C1). The first capacitor (C1) is initially pre-charged at the second predetermined voltage (Vp2). The measurement circuit (5) is configured to arrange the first switch (SW1) in an off state when the differential voltage across the first capacitor (C1) has changed with respect to the second predetermined voltage (Vp2) by the reference voltage (Vref). By using the measurement circuit (5) to measure the differential voltage across the first capacitor (C1) and to turn off the first switch (SW1) when the differential voltage across the first capacitor (C1) has changed with respect to the second predetermined voltage (Vp2) by the reference voltage (Vref), an accurate control of the charge change in the first capacitor (C1) is provided. The charge change proportional to the reference voltage (Vref) is a measure of an amount of charge that is transferred to the gate terminal (G) of the power device (12a) to turn on the power device (12a). |
