ADRF5420 RF switch to 90GHz-Breaking new ground in millimeter-wave field

In the RF community, there has long been a consensus: the higher the frequency, the more the design difficulty escalates exponentially, especially when entering the millimeter-wave band. Even a small RF switch must overcome multiple bottlenecks in materials, processes, and performance.

Recently, RF School noticed that Analog Devices (ADI) dropped a bombshell—introducing the ADRF5420 reflective single-pole double-throw (SPDT) RF switch, which pushed the operating frequency up to 90GHz, breaking the high-frequency ceiling of silicon-based RF switches. This delivered a delightful surprise to RF engineers and brought millimeter-wave applications one step closer to practical implementation.

The RF switch, acting as the "traffic controller" of signal pathways, primarily functions to manage the on/off and switching of RF signals. Though seemingly simple, it directly determines the signal quality, power consumption, and reliability of the entire RF system, especially in high-frequency scenarios where minor performance deviations can lead to system failure.

Historically, many silicon-based RF switches had frequency limits capped at 60-80GHz. To surpass 90GHz, challenges include addressing signal attenuation and insufficient isolation while balancing low power consumption and miniaturization—making the task highly non-trivial. Analog Devices' newly introduced ADRF5420 achieves this 90GHz breakthrough through its optimized flip-chip design using silicon technology. Unlike traditional GaAs processes, silicon offers cost and integration advantages.

By refining the process and optimizing the structure, Analog Devices enables this silicon-based switch to overcome high-frequency limitations, covering an operating frequency range from 1GHz to 90GHz—achieving full-bandwidth coverage across conventional RF bands and extending directly into the millimeter-wave high-frequency range.

This single switch can adapt to diverse high-frequency applications, significantly reducing engineers' design complexity.

What is even more remarkable is that the ADRF5420 maintains outstanding performance at high frequencies, which is its most commendable feature. For radio frequency engineers, insertion loss is of utmost concern. This switch achieves less than 3.0dB insertion loss in the 90GHz band. It's worth noting that reducing insertion loss by just 0.1dB in high-frequency bands requires significant design efforts.

With an isolation of better than 3dB, it effectively prevents signal crosstalk and ensures signal transmission purity, which is crucial for millimeter-wave communication, radar, and other applications with extremely high signal quality requirements.

Additionally, its straight-through RF input power handling capability reaches 24dBm, while the thermal switching path is 21dBm. This high power handling capability enables it to operate in more complex high-frequency environments and prevents device damage from excessive power

In terms of power consumption control, ADRF5420 also continues ADI's consistent advantages. When powered by a+3.3V positive power supply, the current consumption is as low as 130 μ A; Even with a negative power supply of -3.3V, the current consumption is only 490 μ A. Its low power consumption characteristics make it suitable for portable testing instruments, military radios, and other power sensitive devices.

 More flexibly, it also supports a single positive power supply mode - simply ground the negative power supply to work normally. Although the switching characteristics and linearity may be reduced in this mode, the small signal performance can still remain stable, providing engineers with more design flexibility.

 This is very practical for simplifying circuit design and reducing system costs.

In terms of control mode, ADRF5420 is compatible with CMOS/LVTTL logic, which is also the most familiar and commonly used control mode for RF engineers. It can be easily integrated into existing systems without the need for additional dedicated control circuits, greatly improving design efficiency.

 In terms of packaging, it adopts a 30 ball, 1.56mm x 2.04mm bump bare chip design, which is compact in size and can meet the needs of miniaturized RF devices. At the same time, its working temperature range covers -40 ° C to+105 ° C, and it can work stably in both high and low temperature environments, with full reliability.

Some RF novices may ask, where can a 90GHz RF switch be used?

In fact, its application scenarios are much wider than we imagine. Firstly, in the field of testing and instrumentation, with the increasing demand for millimeter wave testing, 90GHz switches can perfectly adapt to high-end testing equipment such as vector network analyzers and spectrum analyzers, achieving precise switching of high-frequency signals and helping to improve testing accuracy. It should be noted that the core component performance of high-end testing instruments directly determines the accuracy of test results. The emergence of ADRF5420 undoubtedly provides a better choice for the development of high-frequency testing instruments. Next is the 5G millimeter wave infrastructure.

Currently, 5G is evolving towards high frequency bands, and millimeter wave communication has become an important direction for 5G advancement due to its advantages of large bandwidth and high speed. The 90GHz frequency coverage of ADRF5420 can perfectly adapt to the signal switching needs of 5G millimeter wave base stations, helping to promote the landing and application of 5G high frequency bands.

In addition, it can also be applied in the fields of military radio, radar, and electronic countermeasures (ECM). The high-frequency characteristics improve the detection accuracy and anti-interference ability of the radar; In the fields of microwave radio frequency and very small aperture terminal (VSAT), the advantages of wide bandwidth and high reliability can also be leveraged to ensure stable transmission of satellite communication.

 Looking back at the development history of RF switches, from low frequency to high frequency, from GaAs technology to silicon technology, every breakthrough is inseparable from the deep cultivation of manufacturers' technology. ADI has used ADRF5420 this time to directly pull the frequency of silicon-based RF switches to 90GHz, which not only breaks the technical barrier of high-frequency switches, but also makes the application of silicon technology in the millimeter wave field more extensive.

 It should be noted that many people previously thought that silicon technology was difficult to break through the high-frequency bottleneck, but the emergence of ADRF5420 completely breaks this cognition and proves the huge potential of silicon technology in the high-frequency field.

For RF engineers, the launch of ADRF5420 is undoubtedly a "load reducing" artifact - a switch covering a wide frequency range of 1-90GHz, without the need to design multiple switch circuits for different frequency bands, which simplifies the design process, reduces system costs and volume, and has excellent performance and flexible power supply modes, making it adaptable to more complex scenarios.

 For the entire RF industry, the emergence of this switch will also accelerate the landing of millimeter wave applications, benefiting both 5G advanced and high-end testing, as well as military and satellite communication fields. It has to be said that ADI has indeed demonstrated its hard power this time by directly lowering the RF switch to 90GHz, which not only showcases its technological accumulation in the field of RF devices, but also sets a new benchmark for the industry.

I believe that with the driving force of ADRF5420, more manufacturers will invest in the research and development of high-frequency RF switches, promoting the entire RF industry towards higher frequency bands, better performance, and lower costs. Our RF engineers will also have more high-quality device choices, unlocking more possibilities for high-frequency design.