This a continuation of my previous question. As Olin suggested, I decided to simulate only Buck-Boost solution for powering my 16 bit ADC. Olin suggested me to add filtering at the output of the Buck-Boost converter. My circuit diagram is given below.

Output waveforms and measured ripple voltage are shown below.

DVDD & IOVDD Rail:

I am getting a ripple voltage of 7.5 mV Peak-Peak.I believe this is not an issue with digital rail. Kindly confirm.

AVDD Rail:

Here you can see that I am getting ripple of 8 mV peak-Peak. The ADC is 16 bit and 1 LSB at 3.3 V = ≈50 µV. The internal reference has ~60 dB PSRR, meaning it attenuates supply ripple by 1000. This shows that the allowed ripple at AVDD = 50 μV × 1000=50 mV.

My measured ripple voltage at the powerline is 8 mV Peak-Peak.

Therefore the Ripple at ADC = (8 mV) / 1000 = 8 uV.

So I believe,I can go ahead with this design. May I know your thoughts.

Update:

In the previous simulation I have considered ESR of Capacitor only and the ESR I selected is 0.004 Ohm. In the below results I considered the ESR of Inductor (MSS4020-103ML) also and it is 0.21 Ohm. Please see the results below.

In the digital rail I am getting a ripple of 41.4 mV (Peak to Peak) and in the analog rail I am getting a ripple of 38 mV (Peak to peak).

DVDD & IOVDD :

AVDD:

May I know Can I go with BUCK-BOOST solution.

Or Do I need to go with BUCK-BOOST + LDO Solution.