The effect of injection damage on a silicon bipolar low-noise amplifier

A study on the energy injection-induced damage, by a pulse-modulated RF signal source, to a silicon bipolar low-noise amplifier (LNA) is described in this paper based on the analysis of pre- and post-injection data of the noise figure and the gain. Experimental results show that both the noise and the gain characteristics of the LNA are sensitive to energy injection. Sample dissection analysis and simulation results also indicate that energy injection damages the base electrode, and thus causes the base resistor r(bb') to increase, and, as a result, leads to an increase of the LNA noise. However, the gain of most LNA samples increases with the injection energy level following the time-based drift failure model of the bipolar current gain hFE. It is found that using the gain characteristics difference prior to and after the injection as the sole parameter to evaluate the damage is insufficient due to the complexity of the effect of energy injection- induced damage.