#32 Linear voltage regulators architectures

This video discusses various LDO classifications. LDOs can be classified based on type of power device, location of dominant pole, fully on chip or not and open or closed loop type. Video also discusses some use cases in the end.

[@jagdishpanpalia7482]

Excited for the upcoming detailed videos on each architecture. Eagerly waiting 😃

[@abhiruplahiri1]

Good stuff as always!

[@RohitSingh-qe6fp]

Good explanation

[@sudhanshusingh1234]

Good to understand

[@IcRDlayout]

I am new😊 LDO voltage😊

[@98505177229850590818]

How did u get VIN MIN IS vout plus 1 for nmos regulator ? Also can u tell whether pmos or nmos works in linear or saturation mode during regulating ?

[@analogsnippets]

NMOS regulator needs gate voltage higher than output voltage. Since threshold voltage of nmos is ~0.7V, I have assumed we would need 1V above vout.

[@analogsnippets]

For most part nmos and pmos work in saturation. For higher load current pmos may enter linear but a good design would try to limit it to corner cases. For nmos if amplifier is supplied by vin then nmos will always be in saturation region.

[@yunusdification]

You would only need Vth in the source follower case.

[@yunusdification]

Infact there can be benefits in PSRR if you use the source follower LDO

[@vladimirvolokitin8367]

@@yunusdification only if you have very good PSRR for your Amplifier. On other hand for PMOS LDO amplifier PSRR should be ZERO

[@yunusdification]

@@vladimirvolokitin8367 yeah good point. the first pole of opamp becomes the dominant pole. So in fact to adjust that pole you add cap at output of opamp to compensate the loop. This cap should also help the PSRR.

[@pikulsarkar7537]

Can you add digital ldo to the list and discuss in details in one video?

[@analogsnippets]

What do you mean by digital ldo? The use case that I gave in video?

[@pikulsarkar7537]

@@analogsnippets No. Loop will be digitally controlled with power mos acting as switches.

[@analogsnippets]

I have only read about it, not actually designed it. So not an expert on this topic.

[@abhiruplahiri1]

Hi Pikul, here is a link to a simple work we did for dig ldo: A. Lahiri, S. Bansal, N. Bansal and M. S. Hashmi, "Digital LDO with analog-assisted dynamic reference correction for fast and accurate load regulation," 2017 IEEE 60th International Midwest Symposium on Circuits and Systems (MWSCAS), 2017, pp. 767-770, doi: 10.1109/MWSCAS.2017.8053036