Hexfet
HEXFET is a trademarked name, associated with International Rectifier, for a family of power MOSFETs built from a dense array of many small hexagonal transistor cells connected in parallel, a cellular design that became one of the well-known commercial embodiments of the power MOSFET. The hexagonal cell layout gave the name, and the approach of tiling many identical small cells together is the key idea: rather than one large transistor, a HEXFET is effectively thousands of tiny transistors wired in parallel, which together handle large current while each cell remains small and well-behaved. HEXFET is significant as a prominent branded power-MOSFET product line that popularized the cellular approach.
The core concept is parallelism: a power MOSFET is built as a large array of small identical cells operating together, so the device handles high current by summing the contributions of many cells. Handling large current in a single monolithic transistor is difficult, but dividing the job among many small cells connected in parallel distributes the current and lets each cell stay small and controllable. The total current capacity is the sum across all the cells, and the hexagonal shape of HEXFET's cells is a particular choice for how to tile them densely across the die. This cellular, highly parallel structure is how the device achieves power-level current handling from fundamentally MOS building blocks.
The hexagonal cell shape reflects a design choice about how to pack many cells densely and efficiently across the chip area. Tiling a surface with cells involves trade-offs in how much active area is used versus wasted, and the hexagonal geometry is one approach to packing cells closely, giving the HEXFET its name and a distinctive cellular layout. The specific shape matters for density and electrical characteristics, but the broader point is that the device is a tiled array of repeated cells, and the choice of cell geometry is part of optimizing how much current-handling capability fits in a given die area.
HEXFET is notable as a branded, commercially successful realization of the power MOSFET that helped make such devices widely available and recognized. As a trademarked product family, it represents how the power-MOSFET concept was turned into concrete, marketable products that engineers could buy and design around, and it became a well-known name in power electronics. Its commercial prominence contributed to the widespread adoption of power MOSFETs, demonstrating that the cellular, massively parallel approach was not just a laboratory structure but the basis of a successful product line serving real power-switching applications.
HEXFET exemplifies the general engineering strategy of building a large capability from many small, identical, well-controlled units operating in parallel. Rather than solving the hard problem of making one big device handle everything, the cellular approach divides the task among many small devices that are each easy to make well, then combines their outputs. This divide-and-parallelize philosophy appears throughout engineering, and HEXFET applies it to power handling: thousands of tiny transistors, each manageable, together deliver power-level performance, which is both the device's operating principle and a broadly useful design lesson.
Read HEXFET as power from parallelism, branded: International Rectifier's power-MOSFET line built from thousands of small hexagonal cells wired together, summing many manageable transistors into one high-current device, a commercially prominent product that popularized the cellular approach to building power MOSFETs.