Engineering topics
Publications and source records attributed to Rax, Bernard G..
This paper investigates flight circuit application bias and irradiation dose rate dependencies (“test as you fly” conditions) in the total ionizing dose (TID) response of various electronic components considered for use in a space radiation environment.
This paper reports recent total ionizing dose (TID) test results post 300 kRad(Si) for a variety of common part types evaluated for use on NASA/JPL’s Europa Clipper mission.
This paper reports proton damage in LED and phototransistor of the Micropac 66179 optocoupler. Analysis of the test data reveals interesting information, such as the dependence of the transistor gain on irradiation and photocurrent.
Proton Displacement Damage (DD) measurements on Isolink OLS049, Micropac 66296-101, 66224-103JANTX, and 66179-003 are reported. The 66179-003 has the worst degradation, 13% of the initial CTR remains when it is used with I(sub F) = 10 mA at 1 x 10(exp 12) 1-MeV n/sq.cm fluence in Silicon. The remaining CTR percentage for OLS049, 66296-101, and 66224-103JANTX are 21%, 32%, and 79% at 2 x 10(exp 12) 1-MeV n/sq.cm fluence in Silicon, respectively.
Radiation hardened linear devices are characterized for performance in combined total dose and displacement damage environments for a mission scenario with a high radiation level. Performance at low and high dose rate for both biased and unbiased conditions is compared and the impact to hardness assurance methodology is discussed.
Evaluation of bipolar linear parts which may have Enhanced Low Dose Rate Sensitivity (ELDRS) is problematic for missions that have very high dose radiation requirements. The accepted standards for evaluating parts that display ELDRS require testing at a very low dose rate which could be prohibitively long for very high dose missions. In this work, a methodology for ELDRS characterization of bipolar parts for mission doses up to 1 Mrad(Si) is evaluated. The procedure employs an initial dose rate of 0.01 rad(Si)/s to a total dose of 50 krad(Si) and then changes to 0.04 rad(Si)/s to a total dose of 1 Mrad(Si). This procedure appears to work well. No change in rate of degradation with dose has been observed when the dose rate is changed from 0.01 to 0.04 rad(Si)/s. This is taken as an indication that the degradation due to the higher dose rate is equivalent to that at the lower dose rate at the higher dose levels, at least for the parts studied to date. In several cases, significant parameter degradation or functional failure not observed at HDR was observed at fairly high total doses (50 to 250 krad(Si)) at LDR. This behavior calls into question the use of dose rate trend data and enhancement factors to predict LDR performance.
The degradation of the LM193 dual voltage comparator has been studied at different TID dose rate profiles, including several different constant dose rates and a variable dose rate that simulates the behavior of a solar flare. A comparison of results following constant dose rate vs. variable dose rates is made to explore how well the constant dose rates used for typical part testing predict the performance during a simulated space-like mission. Testing at a constant dose rate equal to the lowest dose rate seen during the simulated flare provides an extremely conservative estimate of the overall amount of degradation. A constant dose rate equal to the average dose rate is also more conservative than the variable rate. It appears that, for this part, weighting the dose rates by the amount of total dose received at each rate (rather than the amount of time at each dose rate) results in an average rate that produces an amount of degradation that is a reasonable approximation to that received by the variable rate.
This paper discusses mechanisms and circuit-related factors that affect the degradation of linear integrated circuits from radiation in space. For some circuits there is sufficient degradation to affect performance at total dose levels below 4 krad(Si) because the circuit design techniques require higher gain for the pnp transistors that are the most sensitive to radiation. Qualification methods are recommended that include displacement damage as well as ionization damage.
This paper describes total ionizing dose (TID) test results performed at JPL. Bipolar and BiCMOS device samples were tested exhibiting significant degradation and failures at different irradiation levels. Linear technology which is susceptible to low-dose dependency (ELDRS) exhibited greater damage for devices tested under zero bias condition.
This paper reports recent Total Ionizing Dose (TID) test results obtained at JPL. Several device samples were analyzed exhibiting significant failure levels and ELDRS effects under biased and unbiased condition.
We present results of continuing efforts to evaluate total dose bias dependency and ELDRS effects in bipolar linear microcircuits. Several devices were evaluated, each exhibiting moderate to significant bias and/or dose rate dependency.