PeakView EM Integrity Verification
A California fabless RF design company recently used PeakView to help isolate and remedy an on-chip EM Integrity design flaw. The problem was detected upon lab measurements of a recent design tape-out. In this case, various performance objectives were being compromised. The company was able to track the problem to an inductor-heavy part of the design. One of the design engineers did some back of the envelope calculations that indicated EM coupling between the inductors might be the source.

The design team got busy and stripped down the design to the essential pieces and built a simulation test bench to test out their theory. Using the general purpose EM simulator they already had in house they set out to create an EM model for the simplified layout. The design team soon began to find the difficulty of their task. After several weeks with very little progress, they contacted Lorentz for help.

In this case, the customer used PeakView HFD to analyze the impact of EM coupling on performance due to several different placements. Here, the individual inductors had been placed too close together resulting in unwanted mutual inductance between devices. The design task here was to quantify (if possible) the EM sensitive parts of the design. PeakView HFD was used in the “coupling-only” mode to extract a model for only the mutual coupling between each device. PeakView HFD converts the EM model to a 9-port broadband model that can be overlaid onto the normal testbench simulation. In this way, PeakView includes the EM mutual-coupling effects directly to the SpectreRF simulation netlist.  Now, each testbench can resimulated with a model that includes the coupling information of interest. The resulting circuit simulations matched the lab measurements!

Armed with this information, the design team was able to quickly identify the major EM sensitivities in the circuit and repair the layout to fix the problem. The team continued to use PeakView HFD to verify the impact of EM coupling for successive layout improvements. After a few iterations, not only was the performance improved, but the area of the design was reduced by squeezing together components but verifying no new EM Integrity flaws were introduced.

Now, PeakView HFD is used early and often throughout the design flow to verify the EM Integrity of the design.

Copyright Lorentz Solution, Inc. 2007

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