Total Dose Effects on Negative and Positive Low-Dropout Linear Regulators

Total ionizing dose (TID) functional failure analysis on positive and negative low-dropout linear voltage regulators is performed. Two parts have been chosen for this article: the LP2953 positive regulator and the LT1175 negative regulator. Different failure mechanisms are observed, which can be modeled with radiation-enabled SPICE simulations. The simulation results are shown to compare well with experimental data. Both voltage regulators contain three blocks, essential for accurate modeling: a bandgap reference, a power pass transistor, and an error amplifier. In this article, simulations were performed on each block independently to analyze the trends in parametric degradation after radiation exposure and describe the failure mechanisms. This article identifies the bandgap circuitry as the primary cause of failure for the negative regulator while degradations in all blocks contribute to the TID response of circuits.