Matching Items (2)
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- All Subjects: Bipolar Junction Transistor
- Creators: Barnaby, Hugh
Description
Space exploration is a large field that requires high performing circuitry due to the harsh environment. Within a space environment one of the biggest factors leading to circuit failure is radiation. Circuits must be robust enough to continue operation after being exposed to the high doses of radiation. Bandgap reference (BGR) circuits are designed to be voltage references that stay stable across a wide range of supply voltages and temperatures. A bandgap reference is a piece of a large circuit that supplies critical elements of the large circuit with a constant voltage. When used in a space environment with large amounts of radiation a BGR needs to maintain its output voltage to enable the rest of the circuit to operate under proper conditions. Since a BGR is not a standalone circuit it is difficult and expensive to test if a BGR is maintaining its reference voltage.
This thesis describes a methodology of isolating and simulating bandgap references. Both NPN and PNP bandgap references are simulated over a variety of radiation doses and dose rates. This methodology will allow the degradation due to radiation of a BGR to be modeled easily and affordably. It can be observed that many circuits experience enhanced low dose rate sensitivity (ELDRS) which can lead to failure at low total ionizing doses (TID) of radiation. A compact model library demonstrating degradation of transistors at both high and low dose rates (HDR and LDR) will be used to show bandgap references reliability. Specifically, two bandgap references being utilized in commercial off the shelf low dropout regulators (LDO) will be evaluated. The LDOs are reverse engineered in a simulation program with integrated circuit emphasis (SPICE). Within the two LDOs the bandgaps will be the points of interest. Of the LDOs one has a positive regulated voltage and one has a negative regulated voltage. This requires an NPN and a PNP based BGR respectively. This simulation methodology will draw conclusions about the above bandgap references, and how they operate under radiation at different doses and dose rates.
This thesis describes a methodology of isolating and simulating bandgap references. Both NPN and PNP bandgap references are simulated over a variety of radiation doses and dose rates. This methodology will allow the degradation due to radiation of a BGR to be modeled easily and affordably. It can be observed that many circuits experience enhanced low dose rate sensitivity (ELDRS) which can lead to failure at low total ionizing doses (TID) of radiation. A compact model library demonstrating degradation of transistors at both high and low dose rates (HDR and LDR) will be used to show bandgap references reliability. Specifically, two bandgap references being utilized in commercial off the shelf low dropout regulators (LDO) will be evaluated. The LDOs are reverse engineered in a simulation program with integrated circuit emphasis (SPICE). Within the two LDOs the bandgaps will be the points of interest. Of the LDOs one has a positive regulated voltage and one has a negative regulated voltage. This requires an NPN and a PNP based BGR respectively. This simulation methodology will draw conclusions about the above bandgap references, and how they operate under radiation at different doses and dose rates.
ContributorsDavis, Parker William (Author) / Barnaby, Hugh (Thesis advisor) / Kitchen, Jennifer (Committee member) / Privat, Aymeric (Committee member) / Arizona State University (Publisher)
Created2019
Description
Bipolar commercial-off-the-shelf (COTS) circuits are increasingly used in spacemissions due to the low cost per part. In space environments these devices are exposed to
ionizing radiation that degrades their performance. Testing to evaluate the performance of
these devices is a costly and lengthy process. As such methods that can help predict a
COTS part’s performance help alleviate these downsides. A modeling software for
predicting total ionizing dose (TID), enhanced low dose rate sensitivity (ELDRS), and
hydrogen gas on bipolar parts is introduced and expanded upon. The model is then
developed in several key ways that expand it’s features and usability in this field. A
physics based methodology of simulating interface traps (NIT) to expand the previously
experimental only database is detailed. This new methodology is also compared to
experimental data and used to establish a link between hydrogen concentration in the
oxide and packaged hydrogen gas. Links are established between Technology Computer
Aided Design (TCAD), circuit simulation, and experimental data. These links are then
used to establish a better foundation for the model. New methodologies are added to the
modeling software so that it is possible to simulate transient based characteristics like
slew rate.
ContributorsRoark, Samuel (Author) / Barnaby, Hugh (Thesis advisor) / Sanchez Esqueda, Ivan (Committee member) / Bakkaloglu, Bertan (Committee member) / Arizona State University (Publisher)
Created2022