A Comparison of DC and RF Pulse Susceptibilities of UHF Transistors

The electromagnetic susceptibility of 2N918 UHF transistors is investigated. A single RF pulse at 240 MHz was applied directly to the base terminal with the emitter terminal grounded. The incident RF pulse power required to cause a 50-percent failure rate is in the 28-38-W range for a 3-μs pulse duration and in the 130-140-W range for a 0.3-μs pulse duration. The data indicate that all three 2N918 versions tested are very similar to one 2N5179 version reported upon previously [1] . We observed that the RF microsecond pulse data fit a relationship EA = KAT 0.5 whete EA is the absorbed pulse energy required to cause transistor failure, T the pulse duration, K a constant, A an emitter area. For both 2N918 and 2N5 179 UHF transistors, the value for EA is 22 ,μJ at T = 1 μs and the value for K is 3.1 kJ/cm2-s0.5 for A = 7.0 × 10-6 cm2. A comparison of RF microsecond pulse and dc microsecond pulse susceptibility data for the 2N918 transistor inadicated that the susceptibility levels are within 4 dB and that dc microsecond pulse susceptibility data may be quite useful as a lower bound for RF microsecond pulse susceptibility data.