Determination of Device Lifetime Under Pulsed Operating Conditions

Junction temperature typically determines the time to wear-out for a power amplifier, and thermal management affects many critical power amplifier design choices such as packaging, gate pitch, and wafer thickness. Pulsed waveforms create a junction temperature that varies as a function of time. Often the maximum temperature during the pulsed waveform is used to determine the failure rate for a pulsed device. This does not accurately reflect the time that a pulsed device spends at lower operating temperatures, however. A methodology is presented here to determine a device's time to failure for a pulsed waveform application. Several examples are provided to demonstrate that a pulsed device's lifetime can be significantly longer as compared to that associated with its maximum pulsed temperature