Vertical FET topology benefits radar, avionics applications By Bill Schweber Planet Analog April 30, 2008 (03:01 PM EST)   Phoenix, Ariz—The HVVFET (high-voltage vertical field effect transistor) from relative newcomer HVVi Semiconductors is a family of silicon power transistors targeted at L-band avionics and pulsed-radar applications such as IFF, TCAS, TACAN, Mode-S and ground-based radar systems. The vendor claims that their innovative FET design is the next generation after designs based on DMOS and LDMOS lateral structures, with a vertical structure which allows heat to be extracted from the hottest spot of the device and flow directly to the heatsink In turn, this allows the single-supply, 24 to 48-V power amplifiers (PA) to offer twice of power density of competitive devices along with a 30% efficiency improvement, operating ruggedness with 20:1 VSWR load mismatch (twice that of comparable devices), and 3 dB more gain than available devices. The greater efficiency also yields a much smaller footprint, or the ability to use a single device in place of multiple amplifier stages. The VSWR tolerance reduces or eliminates the need, and thus the cost and board space, for isolators and circulators common in these applications, while the 48-V operation supports reduced current and thus higher-efficiency, higher-reliability operation. The initial offering from HVVI includes three devices: The HVV1011-300, for pulsed applications in the L-band from 1030 to 1090 MHz. It provides over 300 W of pulsed output power with 15 dB gain and 48 % typical efficiency, at pulse widths of 50 microseconds and pulse period of 1 millisecond. It is housed in an industry-standard flanged package. In lots of 1 to 49 pieces, the FET is $398.31. The surface-mount HVV1214-25 for pulsed radar applications in the 1.2 to 1.4 GHz L-band range, with 25 W output. Typical gain is 17.5 dB with 200 microsecond pulse width and 10% duty cycle. Low-volume price is $135.69. The flanged HVV1214-100, with 100 W output and 19.5 dB typical gain, under the same conditions as the HVV1214-25. Low-volume price is $226.15. Engineering evaluation kits are available which include PC board, PA FET, connectors, and heat sink, if necessary.—Bill Schweber Availability: All three products are sampling now, with volume production 3Q 2008. Data sheets and more information: HVVI Semiconductors, www.hvvi.com