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Leon, Rosa

Publications and source records attributed to Leon, Rosa.

5 records
All sourcesNASA NTRSDOE OSTI
NASA NTRS2011

Qualification of emerging point-of-load regulators for next generation power systems

As demand for high-speed, on-board, digital-processing integrated circuits (ICs) on spacecraft increases (FPGAs and DSPs in particular), the need for the next generation point-of-load (POL) regulator becomes a prominent design issue. Shrinking process nodes have resulted in core rails dropping to values close to 1.0 V, drastically reducing margin to standard switching converters or regulators that power digital ICs. The objectives of this study are to first identify reliability issues or additional space reliability requirements that might not be addressed for commercial application of POL converters; second, to study the performances of existing or emerging POL converters (including linear regulators) within a practical two-stage power distribution architecture; and, finally, to identify points of failure at extreme temperatures (low and high) beyond specifications.

Leon, Rosa↗
NASA NTRS2009

Failure modes and low temperature performance of DC/DC converters

Several standard tests to evaluate key (direct current) DC/DC converter parameters were performed on different models of hybrid radiation-hard DC/DC converters. These tests were done to assess both performance and reliability during space applications that operate the converters at temperatures below the lower military range of -5°C. One of the converters failed near -110°C, but another DC/DC converter model started normally at temperatures as low as 140°C. The latter showed acceptable performance during turn-on, load transient, and synchronization tests even though some minor anomalies were observed. These results show good promise for its use in applications where the DC/DC converters will be operated at lower temperatures. An application circuit was also built and preliminary tests were performed on a commercial (low drop out) LDO type of DC to DC converter with adjustable output voltage. These can be used in point of load (POL) applications. This latter device functioned properly on the few tests that were performed; however, more testing is needed to identify potential issues with space use of this and similar devices.

Leon, Rosa↗
NASA NTRS2008

DC to DC Converter Testing for Space Applications: Use of EMI Filters and Thermal Range of Operation

Several tests were performed on Interpoint and International Rectifier (IR) direct current (DC) to DC converters to evaluate potential performance and reliability issues in space use of DC to DC converters and to determine if the use of electromagnetic interference (EMI) filters mitigates concerns observed during previous tests. Test findings reported here include those done up until September - October 2008. Tests performed include efficiency, regulation, cross-regulation, power consumption with inhibit on, load transient response, synchronization, and turn-on tests. Some of the test results presented here span the thermal range -55 C to 125 C. Lower range was extended to -120 C in some tested converters. Determination of failure root cause in DC/DC converters that failed at thermal extremes is also included.

Leon, Rosa↗
NASA NTRS2003

Design and Varactors: Operational Considerations. A Reliability Study for Robust Planar GaAs

Preliminary conclusions include: Limits for reverse currents cannot be set. Based on current data we want to avoid any reverse bias current. We know 1 micro-A is too high. Leakage current gets suppressed when operated at 120K. Migration and verification: a) Reverse Bias Voltage will be limited; b) Health check with I/V curve: 1) Minimal reverse voltage shall be x0.75 of the calculated voltage breakdown Vbr; 2) Degradation of the Reverse Bias voltage at given current will be used as indication of ESD incidents or other Damages (high RF power, heat); 3) Calculation of diodes parameter to verify initial health check result in forward direction. RF output power starts to degrade when diode I/V curve is very strongly degraded only. Experienced on 400GHz doubler and 200GHz doubler

THz frequencies↗