Do you yet need these informations?
I've performed some measurements on bandgaps, so I have some ideas!

Let me know if you are interested!

ywguo wrote on Mar 13^th, 2004, 12:34am:

I know how to define PSRR of an amplifier circuit..  
you have to take the ratio of the gain from the supply to the output and the gain from the input to the output..

Say you get the gain from the supply to the bandgap output.. - what are you going to use for the OTHER side of the ratio???
Since I don't have time to do a textbook or google search for you.. I'll hope that asking this question helps you along the road to finding the answer you need..

SATurn wrote on Oct 25^th, 2006, 1:48am:


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)

I used the SOLT (Short - Open - Load - Thru) calibration method. The measurements I performed were directly on die, so there were no effect of package and bonding wires and pads.
However it's possible perform the measurement also on package but you need to perform an accurate de-embedding of the measurement setup and of the stray capacitances of the PCB where you are testing the BGR.

mg777 wrote on Feb 20^th, 2007, 10:29am:

ywguo wrote on Feb 26^th, 2007, 11:31pm:


I think that depends on the frequency you want to measure PSR. At low frequency I think it's not possible to measure PSR. At high frequency is possible (as I wrote before) but you have to use network analyzer for high frequencies. Maybe at intermediate frequencies you can try to superimpose a signal of known amplitude to the supply voltage by means of a big size capacitor to decouple ac from dc and with an inductor to force the ac signal to enter the BGR. Then you can try to measure the residual output ac signal by means of an oscilloscope. The limits are various, like the precision of the oscilloscope and the fact that the input impedance seen in the supply net can reduce the signal amplitude (impedance divider). But maybe you can obtain something, it depends on what you exactly are trying to do.

Why do you need to measure PSR?

Bye bye

Monte