The Designer's Guide Community Forum

The Designer's Guide Community Forum
https://designers-guide.org/forum/YaBB.pl
Design >> Mixed-Signal Design >> About PSRR
https://designers-guide.org/forum/YaBB.pl?num=1100763670

Message started by serdes on Nov 17^th, 2004, 11:41pm

Title: About PSRR
Post by serdes on Nov 17^th, 2004, 11:41pm

Hello everyone
I have been confusing by the psrr,such as in op or bandgap,ldo. I can`t know how to figure the impact
on my circuit,especially on op.Can you show me some marterial on it?
Best regards

Title: Re: About PSRR
Post by sheldon on Dec 10^th, 2004, 7:30pm

Hi,

Don't have any material just some comments:

1) Simply put power supply are inputs. PSRR gives the ratio
of the gain from the power supply to the output over the
gain from the standard inputs to the output.

2) While PSRR is typically specified as XdB at YHz, you also
need to consider the dc levels of the inputs, the
output, and the power supply. All of the dc levels and
can effect the ac results.

3) Depending on the circuit, i.e., differential circuits, there
may be canceling due to symmetry. In that case, you
need to analyze the effect of device mismatch on PSRR.

4) Measure the open loop gain, and then move ac
input to the power supply terminal and then take the
ratio., the ADE calculator is good for this type of
calculation.

Sheldon