Electronic – Linear Regulator: MOSFET vs BJT


Currently I am doing a project on a voltage regulator. Can you tell me some advantages of MOSFETs over BJT? Apart from a higher power loss, I can not find much. In control engineering it is much more difficult to deal with them. Would be great if you could tell me a few.

Best Answer

In a linear regulator, switching speed isn't a consideration. However, BJT base current can be. There's no steady-state gate current in a MOSFET so a MOSFET can be lower loss.

Also, a MOSFET in the on state looks resistive, so the dropout voltage can be very small at low currents. A BJT will saturate and may lead to higher dropout voltage at low currents.

At higher currents a BJT can suffer from low current gain.

All of these things can be mitigated by proper design, but they are definitely considerations when choosing a pass element.