Electronic Design

HVVFETs—New In Town

The HVVFET is the brainchild of HVVi chief technology officer Bob Davies, one of the key inventors of LDMOS 15 years ago. Devices utilize a vertical FET structure (something that’s been tried before) because it provides higher power density than lateral devices. The problem with those early efforts were the parasitics associated with silicon substrates. That limited operating frequencies.

For HVVi, Davies came up with a novel edge termination structure and a unique gate-drain Faraday shield that reduces these effects. Also, short gate length translates into smaller capacitance. HVVi created a process for ON Semiconductor’s fab that results in repeatable, manufacturable gate lengths as short as 0.2 µm. Augmenting the intrinsic heat dissipation of the vertical structure, HVVFETs also use a special packaging approach that places the highest heat-producing part of the die within microns of the device heatsink.

The three HVVFET products just announced are L-band parts: the 25-W HVV1214-25, the 100-W HVV1214-100, and the 300-W HVV1011-300. The 25- and 100-W devices offer 19- and 20-db gain, respectively, and operate from 1.2 to 1.4 GHz. The 300-W device offers 15-dB gain and operates from 1.030 to 1.090 GHz. They all operate from 48-V supplies and shrug off load mismatches, being able to handle voltage standing wave ratios (VSWRs) as high as 20:1.

That ruggedness is a significant advantage in amplifier design, because the weight and cost of magnet-based circulators and isolators can be eliminated. The spider chart in Figure 5 compares the HVV1011-300 with conventional silicon BJTs and LDMOS parts from other manufacturers.

The 100- and 300-W products are housed in standard flanged packages. The 25-W driver device comes in a surface-mount package. Evaluation kits and small quantities are available now, with volume production in the third quarter. Orders may be placed with Richardson Electronics or directly with HVVi.

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