During a Saturday afternoon of closet organizing, I found my first laptop from 2002—a Dell Inspiron 8200. I remember paying a premium—over $2,000 I think—for the Pentium 4 processor and the 256MB of RAM. It required 4.5A at 20V (90W) and weighed 8 pounds 3 ounces, which is just slightly less than the current weight of my two-week-old daughter. While organizing my closet, I was also listening to a podcast on my $250 phone that easily fits into my pocket and is far more powerful than the old laptop.
Both consumers and defense primes are demanding increased performance, in smaller packages, at lower prices. We have come to expect this level of improvement in each new smartphone generation. Addressing new emerging threats in the defense space requires a similar advancement. In this third post of my series on the intersection of the RF commercial and defense industries, we will examine the need for products that are smaller, more capable, and less expensive. Packing more circuitry into smaller areas is no easy task and to be successful, a company must embrace innovation and modular design—the subjects of my first and second posts in this series. This applies to designing a smart phone or a radar system.
SWaP Optimization in the Defense Industry
Countering IEDs requires jammers small enough to fit in a backpack and affordable enough for widespread use. Low earth orbit satellites require small and lightweight RF modules to keep the launch prices low. The trend of replacing large TWT amplifiers with low-cost, compact GaN SSPAs is intensifying.
When compared to consumer cell phones, the market for high-reliability RF hardware is extremely small. This means the development costs can’t be amortized over millions of products. In order to optimize size, weight, and power (SWaP), the defense industry requires a novel approach.
At Mercury, this novel approach forms the basis of our RF design philosophy—innovative, modular and compact. Instead of taking old technology and attempting to shrink it, we use new and innovative technology such as GaN-based amplifiers and advanced cooling techniques. In order to reduce our cost and keep the price low, we use a modular design approach to enable technology re-use when possible. We also invest in the advanced manufacturing capabilities that enable high-density integration.
To understand this better, we will look at a specific example—an ultra-compact GaN power amplifier. Compared to using GaAs semiconductor devices, GaN allows for much higher power density due to its high breakdown voltage. Instead of around 15V for other technologies, GaN power amplifiers can have a drain bias greater than 50V. What all this means is that you get much more output power from similarly sized devices.
However, as with everything in RF engineering, successfully creating a GaN power amplifier is in the details. With this higher power density comes cooling challenges. The die attach process must be carefully optimized to ensure sufficient heat transfer to the housing. Compared to GaAs and as a function of input power, the gain of GaN starts rolling off further from its saturated level. To address this Mercury is developing linearizing technology. Additionally, the high bias currents require circuitry that can quickly switch high currents.
From the example above, we see that employing the latest technology requires innovation across multiple disciplines. To achieve a cost effective solution, Mercury develops these processes and technologies that can be used across multiple products. It is this method of focused innovation that enables the next generation of ultra-compact RF modules.
For an example of ultra-compact, modular technology take a look at Mercury’s new digital and RF integrated architecture.
Part 4 in the series is now available. Learn how Mercury Systems takes an innovative approach to RF manufacturing.