(Solved): Figure Q6(a) shows a power MOSFET switched from a control circuit and driving a dc load. (a) Explai ...

Figure Q6(a) shows a power MOSFET switched from a control circuit and driving a dc load. (a) Explain why the gate drive output signal cannot share the same ground as the

supply. [3 marks] (b) With the help of a diagram, outline one method for implementing the isolation stage. [5 marks] (c) The power MOSFET has a gate threshold voltage of

. Its corresponding gate charge curve is shown in Figure Q6(b). The device has a switching frequency of

and is required to turn on within

. (i) Calculate the current sourcing capability of the gate drive, and the value of the gate resistance.

(ii) Estimate the current rise time and voltage fall time, if the current calculated in Part (c)(i) is applied to the gate.

F1gure Uo(D)