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Innovations are born out of the usual

Posted: 16 Jun 2004 ?? ?Print Version ?Bookmark and Share

Keywords:power amplifier? cmos? innovation? engineer? invention?

Paul: The greatest perk of being one of the few lady engineers is "there wasn't a waiting line for the ladies' restroom."

Sometimes all the answers come to us in our most relaxed moment, rather than during our intense concentration. Relaxation opens the way to thinking out-of-the-box. Archimedes, who founded the principle of buoyancy, got the answer while taking a bath. Friedrich August Kekule, who discovered the structure of benzene, did so in his momentary sleep.

Great stories and ideas such as these have to do with out-of-the-box thinking. Here's another validation.

One of the industry's principal roadblocks for the development of CMOS power amplifier has been overcoming the gate oxide breakdown. Traditional non-linear power amplifier architectures, such as Class-E power amplifiers, generate voltages significantly in excess of what the CMOS gate oxide can tolerate. Thus, traditional architectures rely on esoteric process technologies, the most common being GaAs. Researchers have been studying this CMOS power amplifier challenge for years, but had little to show for their efforts.

In March of 2000, Nav Sooch, founder and chairman of Silicon Laboratories, gave Susanne Paul and her team just three weeks to figure out how to design a power amplifier in CMOS. Paul was faced with a crisis of having one of the most rewarding and challenging projects of her career.


With professors of physics and biochemistry as parents, Paul's interest in technology drove her to the Massachusetts Institute of Technology (MIT). She shared a joke that the greatest perk of being one of the few lady engineers is "there wasn't a waiting line for the ladies' restroom in the school."

After her undergraduate work, she started her career at Digital Equipment Corp. as a circuit design engineer where she participated in the development of the initial Alpha microprocessor. She then worked at MIT's Lincoln Laboratory as a design engineer for infrared and visible electronic imager ICs.

After five years in work and encouragement from her employers, Paul decided to pursue a master's and Ph.D. in electrical engineering at MIT.

In 1999, Paul prepared her thesis on a pipelined over-sampling ADC under the direction of Professor Hae-Seung Lee. She presented it at the International Solid State Circuits Conference (ISSCC) that year where one of the three founders of Silicon Laboratories, Jeff Scott, also an MIT graduate, met with Professor Lee. "I asked Professor Lee who's the best graduate student he had," said Jeff Scott, "He said without a doubt that it was Susanne Paul, so we invited her to Austin."

The solution

Paul had to solve the industry's long-standing problem quickly, and she was not about to give up on it. One instance, while working on her lawnmower at home, the solution suddenly struck her. In her "aha!" moment, Paul thought up an entirely new architecture that would work within the constraints of CMOS and immediately knew she had solved the problem. The next day, she drew out the architecture for the CMOS power amplifier in less than 10 minutes, and the initial topology remains unchanged today.

By thinking beyond traditional ideas, Paul implemented a circuit approach rather than a device physics approach, allowing innovation at the circuit level using standard process technology. Paul discovered a novel way of distributing the high voltages generated during amplification among multiple devices. Using this new architecture, no single device is subjected to any voltage greater than what the gate oxide can tolerate. This fundamental breakthrough allowed Silicon Laboratories to proceed with the creation of a CMOS GSM/GPRS power amplifier, which some are calling one of the most significant RF innovations in a decade.

No one on Paul's team had any experience in RF design, an intentional decision on behalf of the management team. The idea was that without preconceived notions, the realm of possibilities would be endless. The result was an innovative solution, a common theme at Silicon Laboratories that results in out-of-the-box thinking.

It's great to know that we have this "little genie" in the corner of our brain box, which would solve our problems for us, as long as we let it do it. It seems that people like Paul knows how to free a genie out of the box. In her case, the key was the lawnmower.

- Park Dong-Wook

Electronic Engineering Times - Korea

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