Problem with S-param simulation in Momentum and Ref Node connection in SP2 Data Item
时间：04-05
整理：3721RD
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Hi all,
I am experiencing something in Momentum S-param simulation results which seems strange to me.
I am simulating a piece of metal on a 2-layer FR4 substrate to see its capacitance to the ground. I use a rectangular piece of metal (Cond) with no Cond2 on the bottom. I put two internal ports on two opposite sides of the rectangular and do the S-param simulation in Momentum. I get the .ds file, put it in a SP2 data item. I leave one port floating and connect a Term to the other port and run an S-param simulation in ADS schematic.
I know that the Ref node is the ground of the circuit so I should connect to the "ground of the circuit" in my schematic. But when I do, I see a capacitance at the input (130fF for 1.5m*1.5m). If there is no Cond2 on the other side (no secondary cap plate), should I not see zero cap value?
When I leave the Ref node floating, I see the cap value is zero as expected.
When I put a big Cond2 plate underneath the metal, then the value of the capacitance is the same when the Ref node is floating or grounded (I put two internal ports for the Cond2 metal as well like the Cond metal). This seems to be OK.
What is going on here?
I am experiencing something in Momentum S-param simulation results which seems strange to me.
I am simulating a piece of metal on a 2-layer FR4 substrate to see its capacitance to the ground. I use a rectangular piece of metal (Cond) with no Cond2 on the bottom. I put two internal ports on two opposite sides of the rectangular and do the S-param simulation in Momentum. I get the .ds file, put it in a SP2 data item. I leave one port floating and connect a Term to the other port and run an S-param simulation in ADS schematic.
I know that the Ref node is the ground of the circuit so I should connect to the "ground of the circuit" in my schematic. But when I do, I see a capacitance at the input (130fF for 1.5m*1.5m). If there is no Cond2 on the other side (no secondary cap plate), should I not see zero cap value?
When I leave the Ref node floating, I see the cap value is zero as expected.
When I put a big Cond2 plate underneath the metal, then the value of the capacitance is the same when the Ref node is floating or grounded (I put two internal ports for the Cond2 metal as well like the Cond metal). This seems to be OK.
What is going on here?