Cosimulation using DDR Wizard
DDR Wizard is a tool designed for DDR designs that can analyze the time domain transient response at drivers/receivers and analyze eye diagrams. DDR Wizard initiates a cosimulation with Ansys Electronics Desktop Circuit/Schematic using the Electronics Desktop-SIwave dynamic link. The DDR Wizard automates the creation of pin groups for power/ground pins and adds ports on the signal and power nets. Users can create a dynamic link or use the SSS/Touchstone workflow, which solves the design first in SIwave and uses the generated s-parameters as a schematic block in Electronics Desktop. The SSS can be adjusted from Network Data Explorer's Broadband settings before being used in Electronics Desktop.
Unless the design includes a dynamic link (e.g., a Circuit netlist, Touchstone, or State Space file), any ports generated during cosimulation are deleted after a solution is generated.
All settings in DDR Wizard can automatically be propagated to the Virtual Compliance toolkit within Electronics Desktop. To access this from Electronics Desktop's Project Manager, right-click a schematic design and select Toolkit > Virtual Compliance Launch - Ansys DDRwizard. For additional information on the Virtual Compliance toolkit, consult the Circuit help.
Nets are classified into one of the following types, based on search string:
- DQ
- DQS
- ADDR
- CLK
- OTHER
Each of these groups is driven by a specific input, which varies based on DDR speed. See: DDR Wizard Settings.
When the final schematic is generated, simulation setup (Transient, QuickEye, AMI) and reports all reflect 2 DDR modes: Read and Write.
- Read Mode – All sources are in sync.
- Write Mode – Extra delay added for sources which are fed in from project variables in Electronics Desktop. By default, DQS nets are delayed by 1/2 bit width of DQ, and CLK nets are delayed by 1 bit width of ADDR.
Using AMI Models
SIwave supports AMI Analysis, with the following caveats:
- Ensure the path containing IBIS AMI files is listed as an IBIS Buffer Directory in SIwave (FILE > Options > Library Directories).
- AMI IBIS models and non-AMI IBIS models cannot be combined.
- Both the driver and receiver side of the net(s) being analyzed must have an AMI model.