Will MOSFETs ever completely replace Bi-Polar Transistors

MOSFET's are suitable for low-voltage (less than 600 volts) switching

- they are excellent for low voltage, high current applications. One new IR part in TO-247 package was rated at 75V, 207 amps (Rds on is something like 50 mohm). Since FET's can switch at high frequency and easy to parallel, such MOSFET's can be used to make high efficiency, low to medium power converters (upto a few thousand watts).

For new high power converters, IGBT (insulated gate bipolar transistor) seems to be the best choice. It incorporates FET to turn on/off the power BJT output section. Upto 1700V, 1000A rated IGBT modules are available as standard parts. Such IGBT's are used for AC to DC rectifier & DC to AC inverter circuits in large (50KVA and up) UPS, inverters, motor drive inverters, etc.