750-W GaN on SiC RF power transistor for aviation applications

September 13, 2013 // By Graham Prophet
Microsemi's new device is intended for commercial and military, ground and airborne, secondary surveillance radar, and collision avoidance air traffic control equipment

Microsemi has expanded its family of RF power transistors based on gallium nitride (GaN) high electron mobility transistor (HEMT) on silicon carbide (SiC) technology with a new 750 W RF transistor.

The MDSGN-750ELMV transistor delivers 750 W peak power with 17 dB of power gain and typical 70% drain efficiency when operating at 1030/1090 MHz to provide the most power in one single-ended device of its type covering this band.

In addition, the new RF device is capable of handling the demanding commercial Mode-S ELM (Extended Length Message) pulsing conditions for both the 1030 MHz ground based interrogators and 1090 MHz airborne transponders.

Features include an ELM pulsing format - burst of quantity of 48 pulses: 32 µs (ON) and 18 µs (OFF), burst repetition period of 24 ms, and long term duty cycle of 6.4. 

Further the device has a drain bias of +50 V (Vdd), a breakdown voltage of >200 V (Bvdss), low thermal resistance of 0.24 C/W and power output temperature stability of -40°C to +85°C (< ±0.7 dB).

GaN on SIC HEMT provides several advantages over alternative process technologies including higher power performance, bill-of-material cost savings, and a reduced device-size footprint. For example, the MDSGN-750ELMV offers the following benefits:

• Single-ended design with simplified impedance matching, replacing lower power devices that require additional levels of combining;

• Highest peak power and power gain for reduced system power stages and final stage combining;

• Single output stage pair provides 1.5 kW peak output power with margin;

• Combining four output stage pairs delivers a full system >5 kW peak output power;

• 50 V bias allows use of existing power supply rail with reduced DC current demand;

• Extremely rugged performance improves system yields;

• Amplifier size is 50% smaller than devices built with silicon bipolar junction transistors (Si BJT) or laterally diffused metal oxide semiconductor (LDMOS) devices;

• Greatly more breakdown voltage headroom than