Level: Beginner
Zoe Toigo, Signal and Power Integrity Engineer, Microsoft
Priya Pathmanathan, Senior Signal and Power Integrity Engineer, Microsoft
Martin Rodriguez, Power Integrity Engineer, Microsoft
Doug White, Principal Signal and Power Integrity Engineering Manager, Microsoft
Ever-increasing complexity of computer systems demands electrical power delivered efficiently to the chip. The design challenge of a power delivery network (PDN) is to provide stable, low-noise voltage through low-impedance paths, which influence overall system performance. Accurate models of a proposed PDN are necessary for initial system architecture decisions and continue to drive layout requirements as the physical design matures.
One portion of the PDN design process involves creating a model of the chip’s package in a 3D electromagnetic field-solver tool (HFSS). Complex S-parameter models from FEM (Finite Element Method) field solvers are often simplified to circuit element approximations. Previously, input parameters to a two-dimensional circuit approximation of the package were manually fitted until the circuit matched the 3D model. However, custom DOE and response surface fitting in JMP reduced the number of experimental simulations and development time for model creation and correlation. The prediction profile revealed the polynomial relationship between 12 factors and six responses. Desirability functions were utilized to determine the values of the factors required to obtain the desired responses. Using this data, predicted responses were correlated to circuit simulations.
Auto-generated transcript...
Speaker | Transcript |
| Zoe Toigo | Hello, my name is Zoe Toigo. I'm a signal and power integrity engineer at Microsoft, and my project is titled Power Delivery Network Model Prediction and Correlation. |
| The power delivery network for the computer chip consists of all the interconnects, from the voltage regulator module to the pads on the chip and the metalization on the die that locally distributes power and return current. |
| Because it interacts with the whole system, its quality is vital to overall system performance. |
| Design of the PDN is ??? throughout the entire product design cycle. Early on, we can create models of proposed architectures and give feedback on |
| how this would impact the system. And then, once the design is further refined, we begin an iterative cycle of working with hardware development to refine our MOD tools to match their performance and to also provide requirements for next revisions of the physical design. |
| Earlier this year I was working on modeling a portion of the power delivery network, the chip package. Because this was done in a finite ??? for HFSS, |
| small changes to the model take a long time to simulate, and so we created a 2D circuit approximation of this model. |
| Because we weren't seeing good fit between the two different models, we turn to JMP to improve this process. We started by creating a 12 factor custom design of experiments platform, where our 12 factors were values of lumped elements in the circuit, such as resistors and capacitors. |
| The out...the table generated by the DOE was used to run batch simulations of the circuit, and then from each of those simulations, we extracted values at port...six ports on the network, |
| which became our six responses of the DOE. After all of that was finished, we did a fit of the model using least squares, and for each of the factors, we saw between a 97 and 99 R square fit. So we are confident using this model going forward to correlate this 3D and the 2D packages. |
| With the...with the prediction profiler, we also applied desirability functions so that we could quickly get to the values of the circuit that would match our |
| our 3D HFSS model. But to use this in the future, the production profiler has the added benefit of being able to tweak to show dependencies between the |
| factors and the responses for small changes. |
| This work would not have been possible without the help of my team members and also some theoretical concepts are leveraged from Eric Bogatin's book regarding power delivery networks. Thanks so much. |
