Lean into mmWave Applications with Power Amplifier Components

Higher wireless data rates were previously achieved through increasingly complex modulation schemes that compressed additional bits into the same spectrum slices. With that approach now hitting practical limits, the future will depend on wider bandwidths rather than denser modulation, whether the objective is designing commercial 5G throughput applications or high-capacity military links. This shift pushes designers into the millimeter wave (mmWave) spectrum, where abundant spectrum enables new capabilities but introduces a very different set of design challenges.

5G communication systems are benefiting from years of research originally conducted by defense companies. For example, defense-born phased array antenna technology, which allows for beam steering and the tracking of multiple targets simultaneously, is now widely adopted in 5G applications to transmit simultaneous data streams to multiple users. Commercial systems increasingly operate in bands like 28 GHz and 39 GHz to access the necessary bandwidth for multi-gigabit links.

Companies such as Analog Devices, Inc. have leveraged their mmWave expertise from defense industry applications to deliver standard components that conform to both defense performance requirements and the manufacturability needed for commercial infrastructure. Advanced surface-mount packaging of high-frequency ICs was instrumental in scaling 5G to mass deployment.

Both the 5G and defense industries rely on advanced high-frequency hardware. While 5G networks optimize for specific, narrow slices of spectrum to maximize throughput, military applications such as electronic warfare (EW) require wide operational bandwidths to ensure spectral awareness. Despite those differences, the push for wide modulation bandwidths in 5G has created a symbiotic manufacturing benefit.

The convergence of these sectors in mmWave technology has enabled the manufacturing scale required for commercial deployment. It has also significantly reduced the costs associated with creating military applications that previously relied on low-volume, expensive “chip and wire” assembly processes.

This scale relies on highly integrated radio frequency ICs (RFICs), phased-array modules, and accessible test solutions that are increasingly available to smaller design shops that historically lacked the budget or the specialization of large defense contractors.

The cross-pollination has also forged a shared testing infrastructure. In the past, testing phased array antennas at 28 GHz and 39 GHz required large, costly anechoic chambers. The widespread rollout of 5G led to the development of affordable, off-the-shelf OTA test solutions that defense companies can use for swiftly resolving product development challenges without substantial capital investment. The availability of proven, application-ready building blocks allows design shops of all sizes to approach mmWave as a manageable subsystem, making it easier to move a promising mmWave application from block diagram to deployable hardware.

Spectrum innovations

For several decades, wireless innovation has drawn from two fundamentally different approaches: encoding more information into each distinct signal state (symbol) or expanding the spectral space available to carry information.

Simpler modulation schemes prioritize robustness and signal integrity, while more complex schemes boost data throughput by conveying additional bits per symbol. Basic modulation represents each symbol with a small amount of information, like a single bit. Designers can enhance system performance by encoding more information per symbol using more complex modulation schemes like QAM or by accessing wider spectral channels in higher-frequency mmWave bands.

Modulation determines how data is packed onto a carrier, but it’s the power amplifier (PA) that ensures the data bits reach their intended destination. In commercial 5G, PAs prioritize efficiency and linearity within specified frequency bands to support high-throughput phased arrays. Military systems, though, usually aim for a wider range of frequencies and more power to improve radar clarity, satellite communications, and ease of use.

Even with increasingly sophisticated modulation, there are fundamental limits to how much data can be pushed through a given carrier frequency (F_C) band. One key principle is that data throughput is directly tied to the width of the channel, i.e. the bandwidth of the modulated signal (F_BW). Achieving higher data rates requires wider carrier frequency channels, akin to switching from a crowded single-lane road to a ten-lane superhighway (Figure 1).

Figure 1: A representation of modulation bandwidth centered on a carrier frequency. (Image source: Analog Devices, Inc.)

There is also the DC limit to consider, which mandates that a signal cannot extend below 0 Hz. When a signal is modulated, it spreads around its carrier frequency in what engineers call the sidebands. But if the carrier frequency is too low, part of this signal would theoretically extend below that limit, which is a physical impossibility. So, engineers must lift the carrier frequency to higher frequencies, like those in the mmWave bands, to ensure the full signal fits comfortably within a usable spectrum. This “absolute grounding” in high-frequency operation is what makes wide, high-speed channels possible in the first place.

Together, these two principles help illustrate why designers are turning to mmWave frequencies for both commercial 5G and defense systems. Once modulation complexity reaches practical limits, the only way to significantly increase throughput is to move the carrier higher in frequency and open much wider spectral lanes. Moving to mmWave, therefore, is not just a trend—it’s a physical requirement for achieving the massive data rates and high-resolution sensing that modern applications demand.

Navigating design challenges

Transitioning to mmWave frequencies reshapes the physical design of wireless hardware in ways that affect both commercial and defense systems:

• Higher frequencies compress wavelengths, enabling the miniaturization of antennas. This miniaturization allows arrays to be directly integrated onto chips or compact modules.
• Shorter wavelengths result in narrower beams, enhancing angular resolution. This means radars can distinguish closely spaced targets, and 5G base stations can precisely focus energy on individual users.
• The widespread commercial deployment of these technologies has led to a shift towards surface-mount technology (SMT). SMT supports the automated production of highly integrated modules in plastic or ceramic packages.

These fundamental changes present both opportunities and new engineering challenges for designers building mmWave systems, such as:

• High-frequency operation that leads to increased path loss, reduced antenna efficiency, and heightened sensitivity to nonlinearity, thermal effects, and parasitic layout issues.
• Wide bandwidth requirements that impose stringent demands on RF front-end components, while system-level constraints, such as phased-array beamforming for 5G or high-resolution radar for defense, further complicate the design process.

Commercial designers must find a balance between efficiency, linearity, and integration to support the extensive 5G infrastructure on a large scale. Defense designers, on the other hand, often need higher output power, wider bandwidth, and adaptable operation across multiple bands for radar, satellite communication, and tactical communications.

Engineers must choose between specialized ICs. The choice often depends on whether the application prioritizes performance optimization or operational versatility.

At mmWave frequencies, path loss increases significantly, and higher-order modulation schemes are more susceptible to distortion. Consequently, for commercial 5G, it’s crucial to ensure that phased array antennas efficiently deliver high throughput across their respective bands. Military systems also encounter similar challenges, although their primary focus is often on maximizing output power for radar range or satellite communication (SATCOM) links.

To address these needs, ADI's HMC863ALC4 offers a band-optimized PA that can be tuned for peak efficiency in a narrow band within the 24 GHz to 29.5 GHz range for 5G applications. It boasts high linearity, a gain of 17 dB, an output power of +21 dBm, and achieves a 22.5% power-added efficiency (PAE) rating, which measures the additional RF power produced relative to the DC power consumed. Housed in a compact 4 mm × 4 mm SMT package, these features enable commercial designers to maintain robust throughput while supporting automated assembly processes. The EV1HMC863ALC4 evaluation board (Figure 2) provides designers with a hardware platform to validate PA performance, thermal behavior, biasing network, and measurement setup before committing to an RF front-end.

Figure 2: The EV1HMC863ALC4 provides an evaluation platform to characterize real-world performance of mmWave narrowband applications. (Image source: Analog Devices, Inc.)

Defense designers often operate across wider bandwidths to achieve high radar resolution or multi-band communications, and may sacrifice efficiency to meet that goal. In such cases, the ADPA7005CHIP PA offers a wide operating range of 20 GHz to 44 GHz and typically achieves a PAE ranging from 8% to 13% depending on the frequency sub-band. It delivers an output power of +33 dBm, a gain of 14 dB, and a simple DC-to-RF efficiency of 45%—all encapsulated in a compact 7 mm × 7 mm SMT package, simplifying integration into compact modules. Its broad coverage and high power make it well-suited for flexible, high-performance defense applications, ranging from high-resolution radar to long-range communications. The ADPA7005-EVALZ testing platform (Figure 3) incorporates a heatsink that assists in providing thermal relief while developing more complex designs to address wideband mmWave applications.

Figure 3: The EVAL-ADPA7005AEHZ evaluation board aids development of more complex wideband mmWave applications. (Image source: Analog Devices, Inc.)

Conclusion

The transition to mmWave frequencies represents a critical shift in global communications and defense technology. Whether for phased-array 5G infrastructure or compact EW systems, integrating mmWave modules requires components that support automated, repeatable assembly while maintaining thermal and signal performance. Designed with careful consideration to bandwidth, linearity, and efficiency, utilizing ADI’s PA components enables designers to meet the demands of mmWave systems for both commercial and military applications.