Comparison capacitor types crtmom_2t vs crtmom_wo

[ICLAY]

Can I know the difference between MOM capacitor_2T and MOM Without poly shielding and which is better in 28n, 5n

Thanks

 

[vivekroy]

Having a poly shielding means you don't have anything underneath your caps and so it does not pick up any noise. It also means you couple lesser noise from your substrate and you also inject lesser noise. Always recommended unless you don't have the area.

What is better? with shielding in general.

 

[ICLAY]

Thank you, sir, for your fast response, I am having a couple of question,

1) I found that crtmom_wo ( 3T RTMOM without poly shielding )* has a poly guard ring, how come?


2) for crtmom_2T ( 2T RTMOM )*, there is no poly in it, so I can use varactor underneath it, right?


* using the ReleaseNote.txt file from PDK

 

[vivekroy]

1. I don't have access to your particular PDK and I cannot say anything about it.
2. Yes. It's a common way to increase the density of decoupling capacitors. Stack MOM on top of device capacitors (make sure they are connected in parallel and not series).