this reason is very useful between gate to source have to put a resistor , i also facing a problem with design inverter i have a write a programming , tested in simulation for one button on/off , but my cases i withouth put any resistor to gate to source then my circuit sometime depend on luck , when i try to off , always reflected to ON, need put two three times only can off. and it without this protection will be easy burn IR2101.....thank for u many comment . i saw it from different opnion at ur posted tq