I've been covering radiation effects over my last few posts and have transitioned into a discussion on these effects with high speed ADCs. It is a logical progression for me considering my time here at ADI with the high speed applications team for high speed ADCs. As I looked at these parts and thought about my current role as an applications engineer for the aerospace team I thought it would be great to talk about radiation effects with these products. In my last installment we looked at TID (total ionizing dose effects).
Recall that the main idea there was to do a pre- and post-irradiation test on the ATE. This gives us information on any long term effects experienced by the ADC when subjected to radiation for an extended period of time. The irradiation is basically like an accelerated life test that exposes the part to a certain amount of radiation to gauge the part's expected performance over its life in space when exposed to radiation repeatedly.
In this month's installment on Planet Analog I discuss the testing for single event latch-up (SEL) on a high speed ADC. You can find my blog here: Planet Analog - Jonathan Harris - Single Event Effects (SEEs) with High Speed ADCs: Single Event Latch-up (SEL).This concept is much like you'd expect in typical testing for device latch-up however, in this case the latch-up would be induced by the irradiation. This is a test that is typically done before other single event effects testing because it can be destructive. There are ways to mitigate the risk and use additional circuitry to detect and prevent a latch-up condition but in many applications a product with latch-up at lower LET values is undesirable. The additional circuitry takes up space and uses power as well as increases cost so it is not preferred but can be implemented in some cases.
As an example in my blog this month I look at the AD9246S test report that shows the device performance for SEL. To look for SEL the device power supply currents are monitored to look for a sudden increase in current during the irradiation of the device. The AD9246S performs really well and exhibits virtually no change in supply current for the test. I've included an example plot below showing the AVDD current for the AD9246S during the test where the device is exposed to an LET of 80 MeV-cm2/mg out to a total fluence of 1.0E+07 ions/cm2. Take a look at my blog on Planet Analog to find out more details. Stay tuned also next month as I continue to look at single event effects for high speed ADCs.