morix
Newbie level 3
![Newbie level 3](/styles/images/ranks/alevel3.gif)
Hi,
I had some difficulties designing a LDO with the following spec:
supply voltage 1.2V
output voltage 1V
output current range 10uA ~ 100uA
layout area must be small (large size resistors cannot be used)
other specs r kinda minor
the structure is a smple LDO consisting one PMOS power MOS, 2 resistors and an op-amp.
The problem I encountered is that since the desired output voltage is 1V and the output current is in ~uA. Therefore, the resistance must be in ~Mohm scale, which must be large in layout. So i'm looking for some thing to replace large resistors or some modification on LDO structure to resolve this problem.
I have tried to replace large resistors with diode-connected loads (PMOS), but there will be other problems, for example, the diode-connected load that is connected between output and op-amp, its resistance will vary when the output loading changes. Thus, we can't come up with a stable output voltage at 1V.
Can anyone give me some help here?
I had some difficulties designing a LDO with the following spec:
supply voltage 1.2V
output voltage 1V
output current range 10uA ~ 100uA
layout area must be small (large size resistors cannot be used)
other specs r kinda minor
the structure is a smple LDO consisting one PMOS power MOS, 2 resistors and an op-amp.
The problem I encountered is that since the desired output voltage is 1V and the output current is in ~uA. Therefore, the resistance must be in ~Mohm scale, which must be large in layout. So i'm looking for some thing to replace large resistors or some modification on LDO structure to resolve this problem.
I have tried to replace large resistors with diode-connected loads (PMOS), but there will be other problems, for example, the diode-connected load that is connected between output and op-amp, its resistance will vary when the output loading changes. Thus, we can't come up with a stable output voltage at 1V.
Can anyone give me some help here?