Hughes Network Systems

With the implementation of simulation based high-speed analysis and verification in the design of three Packet Radio Channel Unit (PRCU) modules, members of the PRCU team are enhancing the way designs are done at Hughes Network Systems (HNS).

“Looking at ICX from a high-level, the tools potentially saved us several board spins. Since each particular board spin is roughly four to six weeks, we saved at least four to twelve weeks in our project schedule.”

PRCUs are designed to transmit packetized data through satellite links in a Software Defined Radio (SDR) format. PRCUs allow frequency ranges and channels to be changed on-the-fly, since the values are not hardwired directly into the RF hardware.

According to Shahana Tanveer, Hardware Design Engineer, “What we think makes this platform unique is the fact that it is flexible enough to be used across multiple projects. We've developed it using programmable FPGAs, so that any program can take the blank platform and program it to perform any particular function the project wants. This means that other teams at HNS do not have to redesign the hardware for multiple projects.”

Specifically, the PRCU modules were designed with small mechanical dimensions, multiple fine and micro pitch BGAs, dense interconnects and cross connects, blind, buried and micro vias, vias in pad and multiple clock domains with speeds exceeding 100 MHz. The most complicated module contains over 4000 digital routes and five BGAs with around 680 pins each.

ICX tools from Mentor Graphics manage signal integrity and ensure first-pass success

First-pass success was critical to the PRCU design team, and in order to ensure it, signal integrity issues needed to be addressed early in the design process. This was done by utilizing the ICX high-speed suite of tools from Mentor Graphics®, including: IS_Floorplanner™, IS_MultiBoard™, IS_Optimizer™ and IS_Synthesizer™.

“Our main criteria for choosing the ICX high-speed suite of tools were the quality of the tools, the associated cost, the flexibility, and the options the tools have.”

ICX provides an advanced design and verification environment for even the toughest high-speed challenges. By integrating physical design with electrical verification, the tools provide a single environment for rules entry, what-if design exploration, timing-driven placement, electrically-driven routing and system verification.

“Because we used ICX up-front when we were doing our board design, our prototypes worked from the very first day we plugged them in. When we were doing functional testing, we didn't have to spend valuable time doing de-bug related to signal integrity or timing issues. Since the board has blind, buried and micro vias, we didn't have access to probe the majority of the signals in the lab. This meant that we wouldn't be able to isolate any problems we might encounter. Because we used the ICX tools, we were able to see the signal quality of every net, including the ones on inner layers. By performing analysis and verification up front, we were able to fix problems directly in the ICX design environment prior to building prototype hardware. Not being able to probe the signals on the finished board was acceptable, because we already knew how the signals would behave. We have been able to go back and do correlation with some of the signals that we were able to measure in the lab, and have had very good results. In other words, what we saw in simulation was exactly what we saw in the lab. Tying that into the signals that we are not able to probe, we knew that those signals were behaving correctly, since the correlation with the other signals was very high. This is difficult to quantify, because if we had not run initial simulations on the board, the prototypes would have likely come back functioning incorrectly.” explains Shahana Tanveer.

Quality tools provide quality designs

Design quality is just as important to the PRCU team as first-pass success. According to David Wojtkowski, Principle Engineer and Manager for the PRCU Design Team, “Without board simulation, you would never have a comfortable feeling whether or not you were going to have problems that would crop up afterwards. What we have with the ICX tools is something that guarantees us quality in the board.”

Added value from Mentor Graphics Design Consulting Services

Mitra Geeban, Mentor Graphics Design Consultant, worked directly with Shahana Tanveer and the PRCU design team, providing knowledge sourcing about the ICX toolset as the PRCU design team introduced SI analysis and verification into their design flow. In addition to assisting with tool setup, configuration and usage, as well as IBIS model creation and verification, Mitra supported the team throughout the implementation of a high-speed design methodology.

“Mitra wasn't here just telling me how to use ICX, he was also helping me with good design practices for routing electrically constrained signals, as well as managing power distribution.”