The Company
Wireless Semiconductor Division (WSD) is a division of Agilent Technologies based in San Jose, California. WSD is focused primarily
on high performance components for wireless standards such as CDMA, GSM, PCS and AMPS cell phones and base stations; wireless local
loop and wireless point-to-point.
NOTE. As of 1 December 2005, Avago Technologies is a new company made up of the former Agilent Semiconductor Products Group: www.avagotech.com
The Challenge
With the RF communication market moving fast, WSD needed a solution that would allow them to keep up with customer demand for semiconductors and still innovate new products.
"We design to a number of specialized parameters that many canned software packages do not address" said Henrik Morkner, R&D section manager for IC design. "One of our original LNA designs required using three separate software packages and took three years and four iterations to perfect." Only with great difficulty was Agilent WSD able to create custom models and tools to simulate parameters
such as NF and IP3 in the same deck. "This in turn allowed us to simulate more complex terms like multi-tone interferers, transmit leakage effects, and maximum current needed versus RF performance. The result was a part designed to work in a system (CDMA phone) and not just to a customer request," said Morkner.
The Solution
Agilent WSD was able to keep pace with the market while advancing new RFIC technologies with the help of Advanced Design System (ADS) software from Agilent EEsof EDA. In conjunction with Cadence, ADS is used as part of both Agilent WSD's GaAs and Si IC semiconductor processes.
The Results
Specifically, WSD needed a novel solution for a Low Noise Amplifier with a bypass switch (LNA/Sw). The device had stringent performance requirements (low noise, high linearity, and minimal current draw when bypassed). "Using ADS we were able to explore traditional topologies and discard them. We then investigated completely new ways to provide this function using ADS and a combination of custom device models," explained Morkner. The result was a product that not only met and exceeded performance requirements, but was volume manufacturable and profitable.
Using the RF analysis capability in ADS, WSD was able to create data presentations that would allow them to see design parameters in detail. The figure below shows the behavior of the LNA/sw in terms of Adjacent Channel Power Ratio that has been characterized by
using a CDMA modulated signal and running a Circuit Envelope simulation. The post-processing feature in ADS allowed for the comparison of simulated data against measured results. In fact, this extensive analysis capability in ADS allowed WSD to conduct research on the LNA/Sw that led to two patents.
Figure ACPR model vs. actual
"Our final performance is 80% more accurate using ADS than it was with the old tools because we were able to predict and link our RF small signal and DC performance in one simulation much more accurately than before. Plus, ADS was able to greatly improve our large signal performance and finally, link it to DC and small signal. This resulted in a much more accurate result than the old way of independent measurements."
After incorporating ADS into their IC design flow Agilent WSD has moved a typical IC design cycle from two years and several iterations to one or two iterations and less than twelve months of development time.
Today, ADS is used extensively throughout the product lifecycle. All devices are modeled on ADS and all topologies are simulated. System simulations of an entire cell phone for example, are used to define key specifications and possible system problems.
"We also use ADS as a marketing tool to supply behavioral models of our IC to customers so they may analyze system simulations using our RFIC." In a specific case a WSD engineer performed a live-simulation in front of a CDMA radio design engineer to propose a solution for resolving an oscillation problem. After playing with ADS, the WSD engineer successfully found the right value of matching circuits and topology, and was awarded the design-win!
Morkner declared, "ADS allows us to predict what specifications for an RFIC the customer needs, before they need it, and then ADS helps to show the customer how to use that RFIC."
For more information about Agilent Technologies Advanced Design System, visit our Website: www.agilent.com/eesof-eda
For more information about Agilent WSD products, go to:
http://www.agilent.com/view/RF
For more information about other Agilent test and measurement products, go to:
http://www.agilent.com/find/tmdir
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