Hi all,


I am designing a PLL, and I have found that the noise performance of the design is limited by the noise performance of the bandgap reference. It occurred to me that my whole system will be limited by the bandgap. For example, for my ADC, the output will only be as accurate as the reference. Not only that, but my power supply is from an LDO which uses the bandgap as a reference. So my supply noise will be at least as bad as the bandgap.

So my question is, do we normally apply very heavy filtering to the bandgap reference? Also, this will ultimately limit the startup of the circuit. So is this usually a big part of the overall system startup time? Do people normally use circuitry to speed up this startup time?


thanks,
Aaron