Radio waves were first mapped out and harnessed back in 1873. Since that time, radio frequencies and microwaves have been used in numerous applications from the telegraph and the first radio broadcasts making their way into people's homes to radar technology and musical instruments. They also paved the way for military drones, satellites, and the internet among other modern-day essentials.
It's no secret that radio waves have little reach and effectiveness on their own. Because of this, RF power amplifiers are needed to increase their bandwidth or boost their power output, efficiency, and gain among other aspects. In the beginning, amplifiers relied on vacuum tubes and bipolar junction transistors. Those soon gave way to solid-state devices, such as metal-oxide-semiconductor field-effect transistors, or MOSFETs. These days, the industry has moved on to bigger and better things, the most common of which are GaAs and GaN.
First Things First
Before delving into the most recent developments in the field, it's important to understand what semiconductors are and why they're important for RF power amplifiers. You may remember from science class that conductors are materials that allow heat or electricity to flow through them. Insulators, on the other hand, block the flow of heat and electricity. Semiconductors fall in the middle of this spectrum. They offer electrical and thermal conductivity that's lower than conductors but higher than insulators.
RF amplifiers essentially take in radio signals, break them down, transmit them over long distances, and reassemble them. Semiconductors facilitate this process in a number of ways. They basically bridge the gap between other components in the amplifier to generate more power, send the signals further, provide greater clarity, and other functions. They also help disperse heat generated by the amplifiers and regulate the flow of electricity without blocking it entirely. This may be an oversimplified explanation of how they operate, but it covers some of the basics.
Taking a Closer Look at GaAs
MOSFETs and silicon-based semiconductors certainly brought about their fair share of advancements in the use of RF and microwaves. Some devices are equipped with them to this day. Still, they're no longer the only option or even the optimal choice in many situations.
GaAs, or gallium arsenide, semiconductors came into play during the 1980s, and they quickly became the go-to solution for RF and microwave applications. They offer several advantages over their limited counterparts. GaAs devices are capable of functioning at frequencies above 250 GHz because of their higher electron mobility and saturated electron velocity. Due to their wider energy band gap in comparison to those of other semiconductors, they don't overheat as easily. They also create less noise interference.
These semiconductors are available in several forms with diameters of up to six inches. Types of GaAs microwave-integrated circuits are used in an array of devices, including tablets and smartphones. Of course, those aren't their only practical uses. They're often the best choice for lower-voltage applications and devices in which reduced noise and interference and high resistance to radiation and heat are required.
Digging Deeper into GaN
GaN, or gallium nitride, semiconductors are relative newcomers to the field. They were developed during the 1990s and commonly used in devices that operate at high frequencies and require significant amounts of power. This type of semiconductor is highly resistant to radiation, making it ideal for military drones and satellites among other devices that could potentially end up in strenuous situations.
Although GaAs devices can withstand considerable levels of heat, GaN transmitters have even higher tolerances. They can also operate at higher voltages than their counterparts. They're more suitable for use with microwave and THz frequencies. Under certain circumstances, GaN transistors provide more efficiency than GaAs varieties. They potentially use less energy and allow less energy loss than other types of semiconductors. At the same time, they tend to have a higher energy output.
GaN has higher electron mobility than GaAs and other semiconductors, so it has a broader amplification range. Despite typically coming in a much smaller package than GaAs, it can rapidly disperse heat to avoid burnout even at extremely high voltage levels. Though GaN technology is more expensive than other options, those who require high-power and frequency capabilities, as well as greater efficiency, insist it's well worth the extra cost.
Comparing GaAs and GaN Power RF Power Amplifiers
Neither GaAs nor GaN power RF amplifiers are right for all situations, but each one certainly has plenty of uses. Simply stated, those who require less noise and interference with ample heat resistance often turn to systems with GaAs semiconductors. In cases where extremely high voltage is required and large amounts of heat are generated, GaN may be the better choice. GaN is also the most suitable alternative when efficiency is of the utmost importance.
Either type of semiconductor can be used to make a wide range of amplifiers. They can also be combined with other materials and components for additional versatility. GaAs is typically used in larger types of circuits and applications whereas GaN is usually more condensed, making it the solution for smaller setups. Still, the most effective option, combination of components, and system layout depend on your unique needs and expectations.
Are These Alternatives Better Than Their Predecessors?
In a nutshell, yes. GaN and GaAs offer numerous advantages over MOSFETs, silicon and other earlier technologies. They last longer, are more resilient, have higher power densities, greater bandwidth capabilities and abilities to work at much higher frequencies. outputs and tolerances, and are much more efficient. Both tolerate heat, radiation, and other hazards more readily than older alternatives.
That's not to say that silicon-based systems don't have their own advantages. Silicon and certain other materials are more readily available and less expensive to process. Silicon is also an excellent thermal conductor with its own built-in insulator. This makes it unique in the world of semiconductors. Though it's a mediocre electrical conductor, it can be mixed with other elements to improve this aspect.
No matter which strengths you're looking for in an RF power amplifier or which applications you have in mind, there's a system out there to suit your needs. If you're not sure which one best suits your requirements, we're here to help. Feel free to reach out to us by phone or through the form on our website. Our team members stand ready to lend you the benefit of their knowledge and experience.