Why pushing power amplifiers into the G-band changes the way we sense, communicate, and defend.

The Power Amplifier: Giving Signals Their Voice

Every wireless system begins with a tiny signal from an oscillator or mixer. But a whisper can’t travel kilometers through the air or illuminate a target on radar. To be useful, that faint whisper must be forged into a crisp and powerful shout, a role made for the RF Power Amplifier (PA).

At everyday frequencies (say below 10 GHz), building PAs is already a balancing act between gain, power, linearity, and efficiency. Push into the G-band (140–220 GHz), and the game gets much tougher:

• Transistors hit their limits in voltage swing (breakdown constraints).
• Tiny parasitics ignored at low frequencies, suddenly behave like full-fledged transmission lines.
• Efficiency stubbornly drops.

Yet, PAs remain the heart of any transmitter. Without them, even the best oscillator is of nothing more than a lab curiosity.

How Power Amplifiers Let Systems See Further

Picture a fighter jet slicing through the sky on a night mission. The pilot cannot rely on his eyes alone. Instead, the jet depends on its radar, scanning the skies with signals that bounce back from hidden aircraft. But here’s the catch: the farther and clearer you want to see, the stronger the radar signal must be. The oscillator by itself is only a whisper. The power amplifier gives that whisper its strength, turning it into a shout that can reach distant targets.

• Stronger PA output means farther radar reach.
• Cleaner PA signal means sharper target detection.
• Higher-frequency PA means finer resolution, like switching from blurry to high-definition vision.

At 180 GHz, we’re at the bleeding edge, these PAs can’t be just labeled as engineering exercises, they’re enablers of future sensing, communication, and defense systems.

When More Power Changes Everything

• Radar: Higher output power pushes detection range further, allowing systems to spot distant targets with greater certainty.
• Wireless Communication: Stronger PAs extend coverage and improve link reliability, which is vital for 6G and beyond.
• Imaging and Sensing: High power improves penetration and resolution, making sub-THz imaging clearer and more useful in security, medical, and industrial inspection.
• Defense Systems: At frequencies like 180 GHz, power amplifiers enable compact, high-resolution radars that can scan wide areas in real time.

Why Push to 180 GHz?

Applications alone don’t explain why researchers are obsessed with pushing into the G-band. The answer lies in the unique advantages of operating at such high frequencies:

• Shorter wavelengths → radar with finer “pixels,” able to distinguish even closely spaced objects.
• Wider bandwidth → data rates in the tens of gigabits per second, critical for 6G and beyond.
• Smaller antennas → the ability to pack massive, phased arrays into compact devices.

Of course, none of this comes for free. At 180 GHz, transistors operate at the edge of their physical limits. Breakdown voltages shrink, signal swings become tiny, and parasitics grow into serious obstacles. Building a power amplifier here means squeezing every bit of performance out of silicon and combining many devices so they act as one.

Inside Our Work on the G-Band Power Amplifier

At Neural Semiconductor, we taped out three 180 GHz common-emitter PAs using 2-way, 4-way, and 8-way Wilkinson combiners. Parallel common emitter devices boosted the effective swing, while the Wilkinson network gathered their output into a single powerful shout, the way many spotlights converge into one beam of light.

References

• Analog Devices. (2018). Understanding RF power amplifiers. Analog Dialogue.
• IEEE Spectrum. (2021, March). The race to 6G: Pushing into the terahertz frontier. IEEE Spectrum.