| 摘要 |
PURPOSE:To calculate thermal resistance by impressing and removing a DC bias voltage and a large-signal input voltage of high frequency to an FET to be measured synchronously, measuring a gate barrier potential right after the impression is released, and knowing internal temperature in large-signal operation. CONSTITUTION:A signal of 4GHz from an oscillator 1 is switched by a variable attenuator 2 with pulses from a pulse generator 14 and a signal which turns on for a time T and off for a time 99T is applied to the gate of an FET10. The changeover switch 17 for the gate 10, on the other hand, is connected to a gate DC bias power source 18 for the time T of the signal impression to apply a pulse voltage for biasing which is amplified by a driver 15 to the drain of the FET10. Therefore, the temperature of the FET10 rises in the continuation time T of the signal impression and when the voltage impression ends, the switch 17 is changed over to a constant current source 11, so that the potential at a gate terminal (b) becomes a potential vgs lower than vgo in normal operation. The thermal resistance Rth in large signal operation is known from said value. |
