如何在OpenStack环境中实现多Region 00 OpenStack中国社区
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发布时间：2022-04-23 06:14
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时间：2023-10-02 16:50
Hi All
I have a difficulty to use global power and ground in Cadence. I am using Spectre.
By using "!" with vdd or gnd, you make them as global. They are recognized in different hierarchy in schematic simulation, so no problem. However, they are not recognized in layout (extracted) simulation.
As you know, there are two common ways to use global nodes. One way is using vdd and gnd symbols and directly connects to a block of your circuits. Another way is giving pins and name them vdd! and gnd!. In either way, there will be no physical nodes to connect to a power source and ground. Simulation in Spectre is no problem in another cellview as a testbench after replacing the symbol.
However, the simulation won't work in layout because the global nodes are not recognized in different hierarchy. For example, let's say an inverter with gnd! and vdd! instead of vdd and gnd. Then there will be no more physical nodes for vdd! and gnd! in symbol view. After placing the symbol in a different cellvew as testbench for simulation, the result does not come out right. For easy test to check whether vdd! works or not, the input pulse signal into the inverter is set at 2.5v. Then, the voltage of vdd is changed to 4v. However, the inverter output is still 2.5v. As matter of fact, it does not invert the input signals. As soon as I change the simulation from the extracted to schematic, the signals are inverted at different voltage level which is 4v.
I believed that it would be the global bonding problem. Therefore, I used "Config" cellview from "Hierarchy Editor". It gave me the same wrong result.
Some recommends using Verilog, but it requires some initial setup which I can't access.
Some recommends using ".CONNECT", but not available in our Cadence
I have found some posts in this forum regarding to the same issues, but there is no such a good answer so far.
Anybody gives me a good solution
Thank you
