Simulation of Power RF GaN Transistors Thermal Parameters in Pulse Mode

This paper contains research results of thermal process in power GaN RF transistor in silicon substrate for pulse mode. Thermal mode research was done using computer simulation. Authors developed methodic allows significant decrease computational complexity. The dependences of maximum transistor channel temperature and thermal resistance as function of pulse width (with constant duty cycle) were done. Thermal simulation was done for power GaN RF transistor with overall gate width 2.1 mm.

Experimental Measurement and Analysis of Pulse Transmission Source of GPR

According to the transmission pulse requirements of the impulse-GPR which probes the objectives of shallow soil, a transmission circuit is designed and made. On the basis of the transistor avalanche theory, avalanche transistor and RF transistor are used to generate the impulse-GPR transmission pulse as the core transistors. Trigger pulse is the square wave which is produced by FPGA as the trigger of whole system, its duty ratio under 10% and its frequency from 50 kHz to 500 kHz. As the results of simulation and actual measurement shown, single transistor avalanche circuit and four transistors cascade avalanche circuit can produce a narrow pulse with its pulse width from 1.337ns to 42.91ns. The results meet the transmission pulse requirements of impulse-GPR which probes the objectives of shallow soil.