lxcpku said:
hello,all
i wonder in a ldo design, the power pmos transistor (that is pass transistor) should be always work in saturation region ? or even triode would also be OK ? some times, simulations is good (since gain still meets the need,and current and output voltage is also good) while mos is not in saturation region, will it be ok ?
thanks a lot
PMOS not always in Saturations. Depend on VIN, VOUT. If
- Vout<VIN-Vdsat, it will be on sat
- Vout> Vin-Vdsat, it will be on triode
If PMOS in saturation PSRR is better.