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The ability to generate and amplify RF signals is nothing new – but solid-state RF energy has enormous potential beyond data transmission applications. As companies like MACOM and collaborative organizations such as the RF Energy Alliance (RFEA) continue to pioneer and develop this technology, enabling greater efficiency and control than previously possible with conventional technologies, the full potential of this technology for mass-market applications is beginning to take form.
Microwave cooking is one application that is already being radically transformed with solid-state RF energy, enabling healthier eating and broad economical benefits. Solid-state RF energy transistors generate hyper-accurate, controlled energy fields that are extremely responsive to the controller, resulting in optimal and precise use and distribution of RF energy. This offers benefits unavailable via alternate solutions, including lower-voltage drive, high efficiency, semiconductor-type reliability, a smaller form factor and a solid-state electronics footprint. Perhaps the most compelling benefit is the power-agility and hyper-precision enabled by this technology, yielding even energy distribution, unprecedented process control range and fast adaption to changing load conditions, not to mention a lifespan of more than 10 years.
Enabling Healthier Eating
Precise temperature control is essential for maintaining proper nutrients of food during the heating/cooking process. Microwave ovens leveraging solid-state power amplifiers enable precision and control of directed energy, which helps preserve the nutritional integrity of food, and prevent cold spots that negatively impact the dining experience.
Since today’s magnetron-based microwave ovens aren’t equipped to adapt to energy being absorbed by or reflected from the food as it cooks, they rely on open-loop, average heating assisted by the rotating turntable at the base of the cavity. This imprecise delivery of energy often results in over-cooking and hot spots that can lower the food’s nutritional value.
By using multiple solid-state power amplifiers and antennas with closed-loop feedback to adjust for precise energy absorption, the energy can be directed with greater precision to exactly where it’s needed and in a controlled way that ensures optimal temperature control. Rather than relying on moisture sensors that measure humidity in the cooking cavity – an indirect mode of measurement that’s sometimes implemented in modern magnetron-based microwave ovens – solid-state microwave ovens measure the properties of the food itself while it cooks, and adapt accordingly. This promotes the retention of the nutrients, moisture and flavors of the food.
The adoption of solid-state microwave heating is expected to commence in the industrial and commercial cooking market, where the value that these systems provide will be well worth the modest increase in cost. Customers stand to gain significant advantages centric to system reliability, food processing speed and throughput.
With regard to system reliability, solid-state RF transistors can provide 10X longer lifespans of typical magnetrons – this is a major benefit in 24/7 production environments where frequent magnetron failures can slow production and require numerous, expensive service calls. By eliminating the rotating platters common to magnetron-based microwave ovens, system reliability is further increased due to the reduction of mechanical moving parts, which are a common point of failure.
Food processing speed and throughput are increased due to solid-state microwave ovens’ ability to heat and cook food much faster than magnetron-based systems, owing to the rapid energy transfer enabled by solid state RF power adapting to the changing food dielectric. Solid-state RF technology is particularly valuable for food defrosting processes, enabling food to be defrosted much faster and more evenly than it can today, without drying or damaging the food.
With continued innovation in solid-state GaN-based RF technology and cost structure improvements, this technology is expected to eventually migrate to consumer kitchens, and in so doing has the potential to change perceptions of the modern microwave oven. Its value will evolve from that of a simple heating device, to a device that’s capable of cost-effectively cooking healthier, multi-course meals with unprecedented efficiency.
This revolutionary cooking technology is already being successfully demonstrated. At IMS 2016, MACOM demonstrated this with our 300 W RF transistor in a solid-state oven baking muffins. The following year, at IMS 2017, MACOM announced their RF Energy Toolkit aimed at accelerating customers’ time to market by making it easier to fine tune RF energy output levels to maximize efficiency and performance.
Earlier this year, at IMS 2018, MACOM demonstrated the controllability of GaN-on-Si-based solid-state RF energy by successfully cooking the traditional Japanese Onsen Tamago. This dish is traditionally slow cooked using rope nets in the water of onsen hot springs in Japan at 70 °C for 30-40 minutes, enabling the egg yolk and egg white to solidify at different temperatures. The result is a dish of unique texture, with both a creamy outer layer and firm inner yolk. With the controllability enabled by solid-state RF energy, MACOM cooked this traditional dish in only 6-8 minutes, achieving the same desired consistency accomplished in the onsen hot springs.
As with any emerging technology, the speed of RF energy technology’s commercial adoption hinges in part on collaborative industry efforts to establish common standards. Organizations like the RF Energy Alliance, composed of industry leaders spanning semiconductor vendors, commercial appliance OEMs and more, aim to help standardize RF energy system components, modules and application interfaces. In turn, this standardization will help to reduce system costs, minimize design complexity, ease application integration and facilitate rapid market adoption (learn more about MACOM’s RF Energy Toolkit).
Thanks to continued advances such as these, the RF industry is closer than ever to enabling a more advanced, smarter kitchen for commercial restaurants and consumers around the world.