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https://designers-guide.org/forum/YaBB.pl Design >> Analog Design >> power transitor leakage https://designers-guide.org/forum/YaBB.pl?num=1157545019 Message started by grosser on Sep 6th, 2006, 5:16am |
Title: power transitor leakage Post by grosser on Sep 6th, 2006, 5:16am hello i mean about LDO circuit again how can i decrease power transistor's (PMOS) leakage under 5uA and under what conditions i should measure it? I do that with the lowest Vdd and no load in every process corner. Trasnsitor has to be large to drive 100mA load under 1.3V so i cannot decrease its width much. It's 15mm wide nad 0.35um regards |
Title: Re: power transitor leakage Post by loose-electron on Sep 6th, 2006, 9:11am Hey there: Leakage tends to be worse at higher temperatures, so I would go to your hot corner, and start by looking there. If this is gate leakage, and getting to zero leakage is important to you, you may want to consider using the I/O transistors, usually higher threshold voltage but thicker gate oxides and less leakage. Jerry |
Title: Re: power transitor leakage Post by grosser on Sep 6th, 2006, 9:17am loose-electron wrote on Sep 6th, 2006, 9:11am:
isn't that drain current under no load conditions?? |
Title: Re: power transitor leakage Post by loose-electron on Sep 7th, 2006, 9:05am You have several different mechanisms happening here. If I remember correctly they all get worse at higher temperatures. |
Title: Re: power transitor leakage Post by Raul on Oct 10th, 2006, 2:34pm Power transistor leakage will be worse under fast-P(for PMOS LDO) corner and hot. Design wise all you can do is to design a circuit that under no-load conditions will drive the gate of the PMOS all the way to supply(at least within 60 mV of the supply rail given the device in sub-threshold conduction). Some people go through the trouble of building a charge pump and connecting the body of the pmos to a voltage that is higher than the supply to increase the VT of the PMOS with the body effect. This will inject noise to the output of the LDO and cost you caps for the charge pump which doesn't really need to drive much current at all. There is really nothing else you can do circuit wise since this is a device physics problem. Everyone has this problem, talk to the fab and see what they can do for you. |
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