> The Micrel datasheet shows a pretty standard source follower > configuration. I checked similar low dropout/low noise regulators > from Linear Technology and they have similar output noise and power > supply rejection. A source follower is an unusual choice for an LDO, since in theabsence of a separate bias supply input, it requires a complex charge pump to bias the gate. re there a significant number like that? The LTC3035 uses that style internally, but is optimized for VLDO, and only has 40 dB attentuation at 100 kHz, rather than 60. Could I inquire which parts you looked at that had similar PSRR? They would be useful to know about. Thank you!

On 12 May 2013 23:51:38 -0400, kevin-usenet@horizon.com wrote: >> The Micrel datasheet shows a pretty standard source follower >> configuration. I checked similar low dropout/low noise regulators >> from Linear Technology and they have similar output noise and power >> supply rejection. > >A source follower is an unusual choice for an LDO, since in theabsence >of a separate bias supply input, it requires a complex charge pump to >bias the gate. > >re there a significant number like that? The LTC3035 uses that style >internally, but is optimized for VLDO, and only has 40 dB attentuation at >100 kHz, rather than 60. > >Could I inquire which parts you looked at that had similar PSRR? >They would be useful to know about. > >Thank you! The Micrel data sheet shows an internal charge pump to create the bias supply. I am not sure now which Linear Technology parts I looked at. I did assume an external bias supply instead of a common emitter/source topology.