Neutron effects on short circuit currents of op amps and consequences

2006

IEEE Trans. Nucl. Sci.

Self Cite

Abstract-The frequency behaviour of irradiated bipolar op amps is always expected to worsen when the device is irradiated. In other words, parameters like the slew rate and the gainbandwidth product are to decrease after either neutron or gamma tests. However, some neutron and TID tests performed on a large variety of bipolar op amps have shown that the evolution of the frequency behaviour is not as simple as it is usually believed. In fact, there is evidence of an increasing influence of the power supply values on the values of the former parameters, which can be extremely important in some devices. Also, the relationship among different frequency parameters has been investigated and, finally, an interesting scarcely reported phenomenon is depicted. This phenomenon is the appearance of spontaneous oscillations in fed-back op amps, without doubt related to a modification of the gain and phase margins of the devices.

Section: A Increasing Influence Of Power Supply Valuesmentioning

confidence: 93%

New Details About the Frequency Behavior of Irradiated Bipolar Operational Amplifiers

2006

IEEE Trans. Nucl. Sci.

Self Cite

“…Previous works [7], [22] have demonstrated that the op amps short circuit current is very affected by the radiation damage and may fall from values on the order of 20-40 mA down to a value lower than 1 mA. In this situation, it will not be strange that the highest current that the op amp may deal with is lower than I 1 .…”

Section: Collapse Of the Primary Op Amp In Pa1xmentioning

confidence: 94%

“…typical class AB stage found in low signal devices [22]. In fact, the output structure is class A in OPA541 and C in PA61, the PA1X devices being class AB amplifiers (Figs.…”

Section: Test Set-upmentioning

confidence: 98%

Degradation of Power Bipolar Operational Amplifiers in a Mixed Neutron and Gamma Environment

2007

IEEE Trans. Nucl. Sci.

Abstract-Power operational amplifiers were irradiated in a mixed neutron and gamma radiation environment. These experiments showed that the degradation of the power operational amplifiers shares a great deal of characteristics with that of the low signal devices (e. g., shift of the input offset voltage, increase of the input bias currents, and degradation of the frequency behavior). However, other phenomena were observed without equivalence in the family (linear dependence of the inverse of the quiescent current on the neutron fluence, more significant degradation of the negative output current and collapse of the primary operational amplifiers). These phenomena were explained from the special characteristics of the output stage, optimized to provide a current of several amperes. Finally, even though power devices are especially sensitive to radiation damage, some of the tested devices are suitable for radiation levels on the order of 5·1013 -10 14 n·cm −2 in case the whole electronic system, in which the device is integrated, is carefully designed.

“…The reason of this drop must be sought in the degradation of the operational amplifier attached to the voltage reference, theory that has been fully developed in [12].…”

Section: 1) Ad565ajdmentioning

confidence: 99%

Radiation tolerant D/A converters for the LHC cryogenic system

Nuclear Instruments and Methods in Physics Research Section A:

et al. 2005

The electronic instrumentation of the LHC cryogenic system is supposed to receive a large dose of total radiation dose (10 This paper focuses on the selection of a radiation tolerant 12-bit parallel input D/A converter, suitable for the system requirements. During a preliminary campaign, some candidates were irradiated to determine the most tolerant device. Once it was discovered, a massive test on this converter was carried out. In this second test, some weak points of the device, as the rad-sensitive voltage reference and the presence of a transresistor, had been removed by means of an external voltage source and a rad-tol op amp.Thus, tests show that the whole system consisting of the D/A converter, external reference and rad-tol op amp could tolerate a total radiation dose up to 5·10