Performance of a high power RF amplifier depends on its resiliency to provide outstanding performance for a much longer period of time that is most likely to be more than 20 years. Resiliency of an amplifier is termed as ruggedness in the electronics world. Most of the amp manufacturers consider ruggedness as one of the most crucial aspects of their design process.
From times known silicon based technologies like bipolar or LDMOS have been used to manufacture high power RF amplifiers. Though they are cost effective, they have low ruggedness ratings. LDMOS has an integral damaging mechanism formed into the structure of the transistor which reduces the function of the amplifier at high operating voltage.
Checking Ruggedness:
At times power supplied to the amplifier can be really high, ruggedness refers to its ability to withhold the power mismatch condition and deliver expected results without any failure or long term degradation. High power amplifier is reliable only if it displays ability to handle huge power distribution internally in the active area without hindering its performance. Although no features or qualities can be used to determine ruggedness it is generally a function of magnitude and phase of the mismatch, the thermal dissipation properties of the amplifier and the output power level conditions.
Semi conductor device manufacturers gauge ruggedness in high power amplifiers differently. Some maintain that the amplifier is ok if the output remains the same under all circumstances. However this is not an appropriate measure because amplifiers manufactured using the Bipolar technology do deliver desired results though the test damages some of the cells. The result remains unaffected because other active cells provide the required power at a higher temperature, so the performance is not affected.
Few others specify that the amplifier can be considered as reliable so far as it does not show more than 20% shift in DC test parameters.
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