File size: 5,152 Bytes
f16fc45 |
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 |
# IR Drop Analysis
The IR Drop Analysis module in OpenROAD (`psm`) is based on PDNSim,
an open-source static IR analyzer.
Features:
- Report worst IR drop.
- Report worst current density over all nodes and wire segments in the
power distribution network, given a placed and PDN-synthesized design.
- Check for floating PDN stripes on the power and ground nets.
- Spice netlist writer for power distribution network wire segments.
| | |
| - | - |
|  |  |
<p style="text-align: center;">(Left): Current Map, (Right): IR drop map</p>
## Commands
```{note}
- Parameters in square brackets `[-param param]` are optional.
- Parameters without square brackets `-param2 param2` are required.
```
### Analyze Power Grid
```tcl
analyze_power_grid
[-vsrc vsrc_file]
[-outfile out_file]
[-error_file err_file]
[-enable_em]
[-em_outfile em_out_file]
[-net net_name]
[-dx bump_pitch_x]
[-dy bump_pitch_y]
[-node_density val_node_density]
[-node_density_factor val_node_density_factor]
[-corner corner]
```
#### Options
| Switch Name | Description |
| ----- | ----- |
| `-vsrc` | File to set the location of the power C4 bumps/IO pins. [Vsrc_aes.loc file](test/Vsrc_aes_vdd.loc) for an example with a description specified [here](doc/Vsrc_description.md). |
| `-dx`,`-dy` | These arguments set the bump pitch to decide the voltage source location in the absence of a vsrc file. Default bump pitch of 140um used in absence of these arguments and vsrc. |
| `-net` | Name of the net to analyze, power or ground net name. |
| `-enable_em` | Report current per power grid segment. |
| `-outfile` | Write per-instance voltage into the file. |
| `-em_outfile` | Write the per-segment current values into a file. This option is only available if used in combination with `-enable_em`. |
| `-voltage` | Sets the voltage on a specific net. If this option is not set, the Liberty file's voltage value is obtained from operating conditions. |
| `-node_density` | Node density (in microns) on the standard cell rails. It cannot be used together with `-node_density_factor`. |
| `-node_density_factor` | Factor which is multiplied by standard cell height to determine the node density on the std cell rails. It cannot be used together with `-node_density`. The default value is `5`, and the allowed values are integers `[0, MAX_INT]`. |
| `-corner` | Corner to use for analysis. |
### Check Power Grid
```tcl
check_power_grid -net net_name
```
#### Options
| Switch Name | Description |
| ----- | ----- |
| `-net` | Name of the net to analyze. Must be a power or ground net name. |
### Write Spice Power Grid
```tcl
write_pg_spice
[-vsrc vsrc_file]
[-outfile out_file]
[-net net_name]
[-dx bump_pitch_x]
[-dy bump_pitch_y]
[-corner corner]
```
#### Options
| Switch Name | Description |
| ----- | ----- |
| `-vsrc` | File to set the location of the power C4 bumps/IO pins. See [Vsrc_aes.loc file](test/Vsrc_aes_vdd.loc) for an example and its [description](doc/Vsrc_description.md). |
| `-dx`,`-dy` | Set the bump pitch to decide the voltage source location in the absence of a `vsrc` file. The default bump pitch is 140um if neither these arguments nor a `vsrc` file are given. |
| `-net` | Name of the net to analyze. Must be a power or ground net name. |
| `-outfile` | Write per-instance voltage written into the file. |
| `-corner` | Corner to use for analysis. |
### Set PDNSim Net voltage
```tcl
set_pdnsim_net_voltage
[-net net_name]
[-voltage volt]
```
#### Options
| Switch Name | Description |
| ----- | ----- |
| `-net` | Name of the net to analyze. It must be a power or ground net name. |
| `-voltage` | Sets the voltage on a specific net. If this option is not given, the Liberty file's voltage value is obtained from operating conditions. |
### Useful Developer Commands
If you are a developer, you might find these useful. More details can be found in the [source file](./src/pdnsim.cpp) or the [swig file](./src/pdnsim.i).
| Command Name | Description |
| ----- | ----- |
| `find_net` | Get a reference to net name. |
## Example scripts
Example scripts demonstrating how to run PDNSim on a sample design on `aes` as follows:
```tcl
./test/aes_test_vdd.tcl
./test/aes_test_vss.tcl
```
## Regression tests
There are a set of regression tests in `./test`. For more information, refer to this [section](../../README.md#regression-tests).
Simply run the following script:
```shell
./test/regression
```
## Limitations
## FAQs
Check out [GitHub discussion](https://github.com/The-OpenROAD-Project/OpenROAD/discussions/categories/q-a?discussions_q=category%3AQ%26A+psm+in%3Atitle)
about this tool.
## References
1. PDNSIM [documentation](doc/PDNSim-documentation.pdf)
1. Chhabria, V.A. and Sapatnekar, S.S. (no date) The-openroad-project/pdnsim: Power Grid Analysis, GitHub. Available at: https://github.com/The-OpenROAD-Project/PDNSim (Accessed: 24 July 2023). [(link)](https://github.com/The-OpenROAD-Project/PDNSim)
## License
BSD 3-Clause License. See [LICENSE](LICENSE) file.
|