SATurn wrote on Oct 25th, 2006, 1:48am:I think in BGR circuits, just the power supply rejection (PSR) is measured ...
SATurn
I just measured the power supply rejection of the BGR from about 100kHz to 1GHz. This because I performed the measurement by means of a network analyzer.
I set the port 1 of the Network analyzer (NWA) as the supply net and the port 2 as the output net. From the scattering parameters with some matrix manipulations I extracted the PSR. The big limitation is due to the fact that usually you have a very low value of PSR at low frequencies, so if you want to measure PSR you need to inject into the BGR a high level signal that can change the response of your circuit (it's not a small signal measurement). If you don't inject a high level signal you can measure the PSR only from a certain frequency (corresponding to the minimum sensitivity of the NWA) up to the instruments limitation (or up to the calibration limitations).
It's also true that if you want to measure the PSR is probably because you want to check the quality of the curve, so you probably can't reach the real PSR curve because of the NWA limitation but yu can check if there are some problems.
I don't know if it's possible to measure directly PSR for low frequencies, maybe by means of indirectly measurements but I've never seen something about it.
Bye bye
Nicola
PS The output voltage noise was measured by means of a True RMS Voltage Meter like HP3457A (it depends on the accuracy you need)