7 June 2011

Microsemi adds GaN-on-SiC devices to S-band RF power transistor family 

Microsemi Corp of Irvine, CA, USA (which designs and makes high-reliability analog and RF devices, mixed-signal integrated circuits, FPGAs and customizable SoCs, and complete subsystems, based on silicon, gallium arsenide and silicon carbide) has expanded its family of S-band RF power transistors to include devices that use gallium nitride (GaN) process technology on a silicon carbide (SiC) substrate. The firm’s GaN-on-SiC high-pulsed power transistors deliver what is claimed to be industry-leading peak power and power gain for radar systems operating in the 2.7–3.5GHz frequency band.

“This is a significant step in Microsemi’s ongoing strategy to extend its product development and marketing initiatives to support the increasingly challenging requirements of next-generation air-traffic control and other radar systems,” says Charlie Leader, VP & general manager. “By expanding our power transistor offering beyond traditional silicon material to use the latest compound semiconductor technologies, we take performance to the next level, create new markets for our products, and demonstrate our continuing commitment to customers in the radar systems development business,” he adds.

Microsemi has leveraged its expertise in S-band RF power transistors to create a family of GaN-on-SiC solutions that are tailored to support the requirements of next-generation systems requiring higher power, better efficiency, and wider bandwidth than is possible using conventional silicon or SiC process technologies. For applications operating in frequency bands up to 20GHz, the wide-bandgap material properties of GaN-on-SiC technology enable smaller systems with improved voltage, gain, broadband performance, drain efficiency, and long-term reliability. 

The new GaN-on-SiC power transistors complement Microsemi’s family of silicon BJT, RF MOSFET (VDMOS) and RF NPN power transistors, including SiC SIT devices that provide superior performance in high-power UHF-band pulsed radar applications operating at frequencies up to 450MHz. The firm also uses GaN technology for a family of enhancement-mode GaN field-effect transistors (FETs) used in satellites and other military power conversion, point-of-load, and high-speed switching applications.

Microsemi’s GaN-on-SiC devices feature drain breakdown voltage well above 350V, enabling them to operate with a drain bias of 60V while delivering much higher reliability than devices manufactured using laterally diffused metal oxide semiconductor (LDMOS) technology. The higher drain bias improves peak power output while yielding more user-friendly impedance levels and simplified circuit-matching requirements across the full system bandwidth. The GaN-on-SiC devices also deliver more than 13dB of power gain and cover 400MHz of bandwidth. 

The new power transistors also reduce system size, e.g. the 2729GN-270 transistor replaces a conventional three-stage Si BJT transistor amplifier consisting of a driver transistor plus one output pallet with two 150W transistors. This substantially reduces system size and complexity while improving system power and efficiency, says the firm.

Microsemi has released two products for each of three frequency bands: 

  • 2.7–2.9GHz band for air-traffic control (pulse format: 100us, 10%; power gain: 13–14dB typical; efficiency of 55–60%): 2729GN-270 (280W power, typical) and 2729GN-150 (160W power, typical); 
  • 2.7–3.1GHz band for air-traffic control (pulse format: 200us, 10%; power gain: 12–13dB typical; efficiency of 50–55%): 2731GN-200 (220W power, typical) and 2731GN-110 (120W power, typical); 
  • 3.1–3.5GHz band for airborne tracking applications (pulse format: 300us, 10%; power gain: 11–12dB typical; efficiency of 45–50%): 3135GN-170 (180W power, typical) and 3135GN-100 (115W power, typical).

Sample units are available for evaluation now. 

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