The VDD/GND connection of guardring

[chang830]

Hi,
We know the guardrings is always used tp protect the noise sensitive analog blocks. I wonder how the vdd/gnd of teh guardrins be connected. someone tied the vdd/gnd of the internal analog blocks to the vdd/gnd of guardrins directly and then routed to the VDD/GND pin. While,someone routed the vdd/gnd of the internal analog block and the vdd/gnd of the guardrings respectively to the VDD/GNd pins. I wonder what's the advantage/disadvantages of these two connectioin methods?

Thanks in advance

 

[k_90]

We hook all the analog blocks together and then star back to the pad, this minimizes metal paths Only very sensitive blocks need be stared back on their own. We have guard rings around each module which is at a set height, whilst this adds a height constraint to every block connecting very block together is very easy at top level and help everything fit together well.

The VDD connects onto the guard ring using metal2 and the substrate is connected in at top-level.

K

 

[zouwanghui]

I think dividing analog block vdd/gnd and guard ring vdd/gnd is prefered way. if possible, they must connect to different vdd/gnd pad; if no more pad space left, you'd better route different power line, and connect them on pad side.

 

[chang830]

We hook all the analog blocks together and then star back to the pad, this minimizes metal paths Only very sensitive blocks need be stared back on their own. We have guard rings around each module which is at a set height, whilst this adds a height constraint to every block connecting very block together is very easy at top level and help everything fit together well.

The VDD connects onto the guard ring using metal2 and the substrate is connected in at top-level.

K

Hello K_90,
Thanks for the useful reply. But you still not clarify how you deal with the vdd/gnd connections of the guardring and the internal analog block.

would you clarify it a bit more?

Thanks