scholarly journals On-line monitoring of base current and forward emitter current gain of the voltage regulator's serial pnp transistor in a radiation environment

2012 ◽  
Vol 27 (2) ◽  
pp. 152-164 ◽  
Author(s):  
Vladimir Vukic ◽  
Predrag Osmokrovic
Keyword(s):  
Automatic Measurement ◽  
Radiation Environment ◽  
Current Gain ◽  
Maximum Output ◽  
Emitter Current ◽  
Base Current ◽  
On Line ◽  
Considerable Degradation ◽  
Loaded Voltage ◽  
Internal Consumption

A method of on-line monitoring of the low-dropout voltage regulator's operation in a radiation environment is developed in this paper. The method had to enable detection of the circuit's degradation during exploitation, without terminating its operation in an ionizing radiation field. Moreover, it had to enable automatic measurement and data collection, as well as the detection of any considerable degradation, well before the monitored voltage regulator's malfunction. The principal parameters of the voltage regulator's operation that were monitored were the serial pnp transistor's base current and the forward emitter current gain. These parameters were procured indirectly, from the data on the voltage regulator's load and quiescent currents. Since the internal consumption current in moderately and heavily loaded devices was used, the quiescent current of a negligibly loaded voltage regulator of the same type served as a reference. Results acquired by on-line monitoring demonstrated marked agreement with the results acquired from examinations of the voltage regulator's maximum output current and minimum dropout voltage in a radiation environment. The results were particularly consistent in tests with heavily loaded devices. Results obtained for moderately loaded voltage regulators and the risks accompanying the application of the presented method, were also analyzed.

scholarly journals Minimum dropout voltage on a serial pnp transistor of a moderately loaded voltage regulator in a gamma radiation field

2012 ◽  
Vol 27 (4) ◽  
pp. 333-340 ◽  
Author(s):  
Vladimir Vukic
Keyword(s):  
Integrated Circuit ◽  
High Current Density ◽  
Negative Influence ◽  
Radiation Hardness ◽  
Voltage Regulators ◽  
Current Gain ◽  
Voltage Regulator ◽  
Emitter Current ◽  
Moderate Load ◽  
Loaded Voltage

The main examined value in an experiment performed on moderately loaded voltage regulators was the serial pnp transistor?s minimum dropout voltage, followed by the data on the base current and forward emitter current gain. Minimum dropout voltage decreased by up to 12%, while the measured values of the forward emitter current gain decreased by 20-40% after the absorption of a total ionizing dose of 500 Gy. The oxide trapped charge increased the radiation tolerance of the serial lateral pnp transistor owing to the suppression of interface trap formation above the base area. Current flow through the serial transistor of the voltage regulator had an influence on the decrease in the power pnp transistor?s forward emitter current gain. Due to the operation with a moderate load of 100 mA, loss of emitter injection efficiency was not as important as during the operation with high current density, thus eliminating the negative influence of emitter crowding on the radiation hardness of the voltage regulator. For a moderate load, gain in the negative feedback reaction was enough to keep output voltage in the anticipated range. Only information procured from tests of the minimum dropout voltage on the moderately loaded voltage regulators were not sufficient for unequivocal determination of the examined integrated circuit?s radiation hardness.

scholarly journals Impact of forward emitter current gain and geometry of pnp power transistors on radiation tolerance of voltage regulators

2010 ◽  
Vol 25 (3) ◽  
pp. 179-185 ◽  
Author(s):  
Vladimir Vukic ◽  
Predrag Osmokrovic
Keyword(s):  
Area Ratio ◽  
Voltage Regulators ◽  
Current Gain ◽  
Maximum Output ◽  
Output Current ◽  
Emitter Current ◽  
Power Transistors ◽  
Operational Characteristics ◽  
Rapid Fall ◽  
A Minor

Low-dropout voltage regulators with various geometries and technological realisations of serial pnp power transistors were exposed to ionizing radiation. Although devices with vertical emitters were considered much less susceptible to the influence of radiation on forward emitter current gain than circuits with round emitters, the experiment showed a similar degradation of current gain in both cases. The main reason of high radiation susceptibility of the examined vertical serial pnp transistor is the implementation of an interdigitated emitter, with high perimeter-to-area ratio, causing the great increase of serial transistor?s base current, but a minor influence on the maximum output current. Transistors with round emitters with small perimeter-to-area ratio expressed a moderate current gain degradation, but a rapid fall of the emitter injection efficiency, causing a significant decrease of the maximum output current. Regardless of the similar forward emitter current gain degradation, reliability and operational characteristics of two types of low-dropout voltage regulators were completely different.

scholarly journals Total Dose Effects on 4H-SiC Bipolar Junction Transistors

2017 ◽  
Vol 897 ◽  
pp. 579-582
Author(s):  
Sethu Saveda Suvanam ◽  
Luigia Lanni ◽  
Bengt Gunnar Malm ◽  
Carl Mikael Zetterling ◽  
Anders Hallén
Keyword(s):  
Total Dose ◽  
Detailed Analysis ◽  
Surface Recombination ◽  
Current Gain ◽  
Bipolar Junction Transistors ◽  
Displacement Damage ◽  
Base Current ◽  
Dose Effects ◽  
Order Of Magnitude ◽  
Total Dose Effects

In this work, total dose effects on 4H-SiC bipolar junction transistors (BJT) are investigated. Three 4H-SiC NPN BJT chips are irradiated with 3MeV protons with a dose of 1×1011, 1×1012 and 1×1013 cm-2, respectively. From the measured reciprocal current gain it is observed that 4H-SiC NPN BJT exposed to protons suffer both displacement damage and ionization, whereas, a traditional Si BJT suffers mainly from displacement damage. Furthermore, bulk damage introduction rates for SiC BJT were extracted to be 3.3×10-15 cm2, which is an order of magnitude lower compared to reported Si values. Finally, from detailed analysis of the base current at low injection levels, it is possible to distinguish when surface recombination leakage is dominant over bulk recombination.

Investigation of Current Gain Degradation in 4H-SiC Power BJTs

2012 ◽  
Vol 717-720 ◽  
pp. 1131-1134 ◽  
Author(s):  
Benedetto Buono ◽  
Reza Ghandi ◽  
Martin Domeij ◽  
Bengt Gunnar Malm ◽  
Carl Mikael Zetterling ◽  
...  
Keyword(s):  
Behavior Analysis ◽  
Carrier Lifetime ◽  
Passivation Layer ◽  
Current Gain ◽  
Degradation Behavior ◽  
Device Design ◽  
Base Region ◽  
Base Current ◽  
Electrical Stress

The current gain degradation of 4H-SiC BJTs with no significant drift of the on-resistance is investigated. Electrical stress on devices with different emitter widths suggests that the device design can influence the degradation behavior. Analysis of the base current extrapolated from the Gummel plot indicates that the reduction of the carrier lifetime in the base region could be the cause for the degradation of the gain. However, analysis of the base current of the base-emitter diode shows that the degradation of the passivation layer could also influence the reduction of the current gain.

SiC BJT's for High Power Switching and RF Applications

2002 ◽  
Vol 742 ◽  
Author(s):  
Anant Agarwal ◽  
Sei-Hyung Ryu ◽  
Craig Capell ◽  
James Richmond ◽  
John W. Palmour ◽  
...  
Keyword(s):  
Single Cell ◽  
Temperature Coefficient ◽  
Supply Voltage ◽  
Maximum Output Power ◽  
Low Frequency ◽  
Current Gain ◽  
Maximum Output ◽  
Positive Temperature ◽  
Power Gain ◽  
Power Switching

ABSTRACTIn this paper, high performance, high voltage NPN bipolar junction transistors in 4H-SiC are presented for applications in low frequency (< 5 MHz) power conversion systems as well as in RF (425 MHz) power amplifiers. The power BJTs for low frequency switching applications were designed to block 1300 V and showed a specific on-resistance of 8.0 mohm-cm2, which outperforms all SiC power switching devices ever reported. Moreover, these transistors show a positive temperature coefficient in the on-resistance and a negative temperature coefficient in the current gain, which enable easy paralleling of the devices. In addition, RF BJTs were designed, fabricated and tested for operation at UHF frequencies. The common emitter breakdown voltage was in excess of 500 V consistent with the 5 micron collector thickness. For VCC = 20 V, fT peaked at about 1.5 GHz. A single cell was measured in common emitter mode with a collector supply voltage of 80 V in class AB at 425 MHz. A 100 μs pulse width with 10% duty cycle was used. A maximum output power of 50 W for a single cell was achieved. The peak large signal power gain was 9.6 dB. The collector efficiency at the power output of 50 W was 51% with a power gain of 9.3 dB. This represents the first demonstration of a SiC RF BJT.

GAIN DEGRADATION AND ENHANCED LOW-DOSE-RATE SENSITIVITY IN BIPOLAR JUNCTION TRANSISTORS

2004 ◽  
Vol 14 (02) ◽  
pp. 503-517 ◽  
Author(s):  
R. D. SCHRIMPF
Keyword(s):  
Dose Rate ◽  
Low Dose ◽  
Surface Recombination ◽  
Rate Sensitivity ◽  
Current Gain ◽  
Bipolar Junction Transistors ◽  
Base Current ◽  
Low Dose Rate ◽  
Two Factors ◽  
Recombination Current

The current gain of irradiated bipolar junction transistors decreases due to increased recombination current in the emitter-base depletion region and the neutral base. This recombination current depends on the interaction of two factors: (1) decreased minority-carrier lifetime at the Si / SiO 2 interface or in the bulk Si and (2) changes in surface potential caused by charge in the oxide. In npn transistors, these two factors both result in increased base current, while in pnp devices, positive charge in the oxide moderates the increase in base current due to surface recombination. In some technologies, the amount of degradation that occurs at a given total dose increases as the dose rate decreases. This enhanced low-dose-rate sensitivity results from space-charge effects produced by slowly transporting holes and protons in the oxide that covers the emitterbase junction.

Hot Electron Transistors Using Si/CoSi2

1987 ◽  
Vol 102 ◽  
Author(s):  
A. F. J. Levi ◽  
R. T. Tung ◽  
J. L. Batstone ◽  
M. Anzlowar
Keyword(s):  
Current Gain ◽  
Material System ◽  
Hot Electron ◽  
Metal Base ◽  
Emitter Current ◽  
Recent Advances ◽  
Electron Transistors

ABSTRACTWe have explored the possibility of fabricating a metal base transistor in the Si/CoSi2 material system. Utilizing recent advances in the growth of thin, pinhole free, CoSi2 layers on Si(111) we have measured the transistor characteristics of a Si/CoSi2/Si structure. The observed low common emitter current gain is attributed to an absence of current carrying states in the CoSi2 transistor base.

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