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Better Alternative for Measuring Linearity of GaN Amplifiers

APPLICATION NOTE: Methods to measure the true linearity of a power amplifier

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GaN devices continue to be a key element in many radar, electronic warfare, satellite and terrestrial communication systems. GaN devices offer a number of advantages. For example, GaN devices have a high breakdown field due to a large bandgap that enables them to operate at higher voltages. Combining this with a high saturation velocity and corresponding large charge capability, GaN devices are ideal for high power applications. Adding excellent thermal conductivity, it is easy to see why the utilization of GaN devices continues to grow. In a recent study, Yole Développement expects the GaN industry to grow with a 23% CAGR between 2017 and 2023, driven by telecom and defense applications.
Some of the most popular GaN devices are wideband RF power amplifiers. Amplifiers are described by multiple characteristics including gain, frequency response or bandwidth, power output, linearity, efficiency, and noise figure. Two key characteristics that are often used to describe the quality of an amplifier are linearity and efficiency. The relative importance of the two attributes depends upon the application. For example, in a satellite-based application, efficiency may be more important as there is limited power available on a satellite. In terrestrial wireless communications, the relative importance may be more equal. Communication systems, such as those based on 5G standards, utilize wideband modulation schemes with significant linearity requirements. In addition, because of the amount of base stations needed to support the systems, it requires acute attention to power efficiency to manage operating expenses. Unfortunately, the power levels to maintain amplifier linearity are often well below the drive levels needed for maximum efficiency.



This article will focus on the applications in which amplifier linearity is the critical attribute. In Figure 1, the blue line illustrates typical amplifier behavior. Linearity is measured by increasing the input power and observing the output power until the amplifier enters compression. Often amplifier linearity is specified at the input power level at which corresponding output power is 1 dB lower than the theoretical linear response, P1dB, which has been historically considered the point at which amplifiers operate most efficiently.

With the simultaneous need for linearity and efficiency, it is crucial to optimize the input back off (IBO) value. Too much back-off sacrifices efficiency and causes the amplifier to be oversized and costlier (to reach the required output power), while too little brings increasing compression and signal degradation. Therefore, measuring amplifier linearity accurately under realistic operating conditions is of considerable value to GaN engineers.



There are a number of alternatives for measuring and expressing amplifier linearity. Three common methods are: 1) characterization of amplifier intermodulation distortion (IMD), 2) noise power ratio (NPR) measurements, and 3) crest factor (CF), or peak-to-average power ratio (PAPR) measurements.ed with the LA-5 linearizing electronics. The meter is supplied with an extended range calibration to give a turndown of 100:1 over the flow range. It can be supplied with either meter-mounted or remote-mounted electronics. High temperature amplified pickoffs are used to eliminate noise generated by the floating (non-grounded) electrical system of the turbine generator. The FT Series turbine meter can be placed inside the generator room due to its compact size and durability under extreme conditions.With the simultaneous need for linearity and efficiency, it is crucial to optimize the input back off (IBO) value. Too much back-off sacrifices efficiency and causes the amplifier to be oversized and costlier (to reach the required output power), while too little brings increasing compression and signal degradation. Therefore, measuring amplifier linearity accurately under realistic operating conditions is of considerable value to GaN engineers


The linearity of an amplifier was measured with all three approaches. Using a Noisecom noise source or a two-tone source, a signal was applied to the amplifier starting from -25 and increased in one dB steps until reaching -15 dBm. The results for each measurement are shown below. Reductions in gain, crest factor, NPR, and the delta between intermodulation products and the carrier signals all indicate an amplifier is behaving non-linearly.

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Steve Moormann VMA manufacturers rep


Field Engineer

Steve originally hails from Chicago and has maintained his strong Midwest values while enjoying the ‘good life’ in the great southwest.  Graduating from Northern Arizona University in Flagstaff, AZ with a B.S. in Electrical Engineering, he started his career in sunny Tucson, AZ and has enjoyed over 30 years in Signal Conditioning and Data Acquisition Systems, in the Industrial Electronics industry.  His varied experience extends from being a Lab Manager to key roles in Technical Sales and International Sales Management. You will likely find Steve on the road visiting customers, friends and family, or watch for him cycling, skiing and exploring both near and far. 

Steve joined VMA in 2020 and is located in our Albuquerque New Mexico office. 

Brandi Fruge VMA VMA manufacturers rep

Brandi Fruge

Inside Sales Engineer

Office Phone: 720-822-4119
Email: [email protected]

Brandi grew up in Katy, Texas.  She graduated from Colorado School of Mines with her Mechanical Engineering Degree in 2015. She previously worked for Schlumberger as a field engineer on frac locations across Texas, Oklahoma, Pennsylvania and more. In her free time, she enjoys traveling, snowboarding, binge watching Netflix and spending time with her dog, Duke. Brandi is located in our Colorado office.

Tracy Grossman VMA Technical Engineer


Field Engineer

Tracy was raised in Arizona and served in the USAF as an Electronic Warfare Technician, completing an Electrical Engineering Technology Journeyman degree from Community College of the Air Force. After the Air Force he worked as a technician before getting his Bachelors in Computer Information Systems at the University of Phoenix. Tracy worked as a Computer Systems Engineering consultant before joining Orbital Sciences (now Northrop Grumman) in 2002, where he worked as an Electrical Engineer for 15 years designing and deploying systems to test and launch rockets. Tracy specialized in Telemetry Ground Systems for several years before becoming the Lead Electrical Engineer on the Antares Ground system design team. After Orbital, he worked as an Embedded Systems Sales Engineer, helping customers find the best solutions to solve complicated design requirements. Starting July 2019, Tracy is on Team VMA as a Field Engineer to continue building relationships and helping engineers find innovative solutions for high-reliability applications. Outside of the office he enjoys spending time with his wife and adult children and his hobbies include Trucks, Hiking, Camping, Hunting, Scuba diving, Motorcycling and church. Tracy is located in our Arizona office.


Field Engineer

Keenan was born and raised in Milwaukee, Wisconsin. Graduated from the University of Denver with his Electrical Engineering Degree with a Specification in Mechatronic Systems. With the need to problem solve and the love to work with people, Keenan has worked in technical sales for the manufacturing, construction, and security industries. From going outside to hike, snowboard, golf, run, or grill to staying inside to cook, read, or simply relax by sitting down to watch a good movie, Keenan loves to spend as much time as possible with his friends and family. Keenan is located in our Colorado office.


Field Engineer

Christie Whitehead Is married and has raised 3 beautiful children, one girl and 2 boys. Her passions are children, education, technology and volunteering. She helped open a Charter school from the ground up in 2000 that is now a top 100 school in the nation year after year. Christie has her bachelor’s degree in Electrical Engineering Technology. She has been in many technology engineering positions and thrives on solving problems. She strives to always add value, have patience and care for others. She loves technology and complexity of the things people are designing. She loves to get into the lab, sharing experiences and knowledge that may help her customers.

Sierra Bishop VMA Staff


Inside Sales

Office Phone: 303-730-7313
Email: [email protected]

Sierra has been with VMA for 4 years.  She previously worked in law enforcement/emergency dispatching for over 9 years.  She is currently going back to school get a bachelors degree in Art and Graphic Design.  She loves travelling and enjoys doing anything ‘artsy’, but especially loves watercolor and oil painting.  When she can she likes to catch a good live theater show. Sierra is located in our Colorado office.

Kristin Hall VMA Staff


Sales Administration

Kristin has been a part of the Vic Myers Associates team for five years now. Prior to her position as Inside Sales and Administration, she worked in the Construction Industry as a Project Manager. Needless to say, she has learned a lot here at VMA, and enjoys being a part of this company. In her free time, she values singing at church, card-making, and spending time with her husband and family. Kristin is located in our Colorado office.

Ron Garcia VMA Engineer


Inside Sales Engineer

Office Phone: 505-884-6878
Email: [email protected]

Ron has worn several hats at VMA over the past twenty years, including inside sales, IT guru, webmaster and application engineer. As a recent empty-nester, Ron and his wife are spending more time on the road, exploring the Southwest. He is an avid sci-fi enthusiast, enjoys playing guitar and listening to jazz. Ron is located in our New Mexico office.

Jim Barnett VMA Staff


Inside Sales Engineer

Office Phone: 480-345-6449
Email: [email protected]

Jim was born in Michigan but has lived in Arizona longer than most natives. He graduated from Arizona State University with a B.S. in Computer Information Systems and holds certifications in Network Administration and Network Security. Jim originally joined Vic Myers Associates in 1991 and has held a variety of positions. Among his interests are hiking, travel, and most things vintage including cars, music, architecture, and artifacts. Jim is located in our Arizona office.

Mark Myers VMA Technical Engineer


Field Engineer, Legend

There a few experiences in my life which I consider invaluable. They include earning my Boy Scout Eagle rank with considerable help and inspiration from my father, serving in the United States Submarine Service during the Viet Nam war, earning a black belt in a mixed style martial arts (it took me 25 years), completing a masters degree (16  years),  becoming a lifelong learner, being engaged in my faith, and ending up with some really good friends.  Professionally, I love being a helper, an ally, a facilitator, a problem solver and someone who is passionate about wanting my friends, my customers and my colleagues to be successful.  Life can be hard, life can be unfair and life can be extraordinary, all at the same time. Mark is located in our Arizona office.

Carlton Davenport VMA Staff


Managing Partner

Office Phone: 505-884-6878
Email: [email protected]

Carlton has traveled and lived all over the U.S. but chose Albuquerque as his home. Carlton and Nancy have raised 3 daughters, grown up and making their own lives now. He joined VMA in 1991 and is responsible for the day-to-day business side, supporting our sales efforts, doing whatever it takes.

Bob Bishop VMA staff


Managing Partner

Bob was raised in Minnesota. Graduated from Minneapolis Technical College with an A&P license. He worked at Rosemount Inc. for a few years and moved to California where he met his wife and gained valuable experience having sold to the test ranges, military bases, and contractors. Bob has been in Colorado serving the same customers for over 30 years. He enjoys muscle cars, travelling, golf and singing in a community choir. Bob is located in our Colorado office.

Ryan Christian VMA Staff


Managing Partner

Ryan was raised in Mesa, Arizona, attended Gilbert schools and graduated from ASU in 2006 with a Bachelors in Interdisciplinary Studies. He went on to complete his MBA at the University of Phoenix Campus in Mesa. Prior to VMA, Ryan worked 5 years as a consumer sales consultant and then 5 years as Analyst at Orbital Sciences, now Northrop Grumman.   Outside of the office, Ryan loves to spend time with his wife, 10yr old daughter and twin 5 year old boys. Ryan loves to get outdoors to hunt & fish as often as possible, serves frequently with kids and adults at church and enjoys quality BBQ time with his friends and family. Ryan is located in our Arizona office.

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