TSMC 65nm capacitor crtmom

[Mounikap]

Hello everyone,

I am using TSMC 65nm. I wanted to use "crtmom" in my circuit. And it has 3 terminals. So anyone can you please let me know whether i need to connect the bulk to either ground(VSS) or power supply(VDD) ? I checked the PDK documents but didn't find information about the bulk connection.

 

[sidun.av]

Hi @Mounikap ,
1. Bulk terminal of crtmom does not affect the performance of the capacitor directly. It is a protective structure that serves as shielding from the substrate noise.
2. Basically, you can connect this terminal to any potential you like (whatever you think is quite and strong enough to provide proper shielding). Usually, the VDD or GND potential is used.
3. Before assigning a net to this terminal, double-check the layout option of this terminal (whether it is PWELL or NWELL). If it is NWELL, it would be better to connect it to VDD, if PWELL - to GND.

Hopefully, that helps.

 

[Mounikap]

Thank you for the information @sidun.av I have attached the capacitor layout diagram. Can you please tell me how can i check the layout option of the particular terminal ? Actually in the Layout i have placed the crtmom capacitor and checked the used metals so in that NW was there so am thinking this bulk should be connected to VDD. Is it correct process ? Can you please tell me how can i check the particular terminal whether it should be connected to NW or PW ?

 

[sidun.av]

It should be mentioned either in schematic or layout PCELL window (when you open Instance properties, or pressing Q). In your case your bulk is connected to NWELL, you can check this by disabling all layers in your layout editor and leaving only NWELL. So yes, your bulk terminal should be using VDD.