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Instrumentation Operates at 210CInstrumentation Operates at 210C

DN Staff

March 29, 2011

4 Min Read
Instrumentation Operates at 210C

Guaranteedto 210C, the AD8229from Analog Devices is being touted the first instrumentation amplifierdesigned and manufactured for hot, harsh and hostile environments. This1.0-nV/vHz low-noise device is specifically targeting extreme, hostileenvironments such as down-hole oil drilling, jet engines and space exploration.

"TheAD8229 is truly a breakthrough product for the oil exploration industry," saysJun Liu, General Manager of Qingdao Zitn Micro-electronics Co. Ltd. "It is nota retrofit of existing components. It was designed from the start forhigh-temperature environments. What this means to Zitn is that we will be ableto operate our equipment longer with less repair time resulting in significantsavings."

Instrumentation Operates at 210C

Instrumentation Operates at 210C

In thepast, designers have been forced to meet the challenges of rugged, noisyhigh-temperature environments with components not specifically designed forhigh-temperature conditions or were designed to operate at lower commercialgrade temperatures. The AD8229 is unique because it solves some of the mostdifficult problems faced by engineers designing electronics for extreme hot,harsh and hostile environments to greatly improve maintenance and operationlifecycle.

"Thetrends we are seeing in the oil and gas industry is that, when exploring fornew sources of energy, companies are often forced to do it in more difficultenvironments," says Pam Aparo, Segment Marketing Manager for Analog Devices'Instrumentation Business. "Companies are forced to drill deeper or at a morehorizontal angle which reduces how efficiently they can cool the drillingapparatus. That's driving the need for components to do measurements at highertemperatures than ever before."

Onechallenge is that the control electronics are housed in close proximity to thepoint of impact. At the bottom of the well or the end of the drill tunnel,classes of drilling such as wireline drilling and logging while drilling (LWD)or measurement while drilling require high temperature electronics.

Whatthese applications have in common is exposing the electronics to high pressure,high temperature (HPHT). Working several miles underground, fixing andre-inserting the drills is a huge problem, and estimates put the total cost forthis type of maintenance operations at millions of dollars per day in the caseof a failure. It's not possible to totally control the systems but goal of theelectronics is to stay operational in these harsh environments.

"Temperatureis a major challenge, along with the type of signals and demanding work done sofar underground," says David Chan, marketing manager for Analog Devices. "Oursystems are very low noise and we're been able to squeeze it down to the pointwhere you can actually detect conditions that even on the surface at roomtemperature would be difficult to deal with."

Thisincludes gamma ray detection and NMR which is the oil drilling version of anMRI where the requirement is to fit that level of instrumentation andsensitivity into a tube 12 inches in diameter. The challenges are quiteextreme, not just the high temperature but also the noise performance that goesalong with it.

"Sittingfive to ten feet from the drill head means that the control and instrumentationelectronics are subjected to a huge amount of mechanical stress and vibrationsin the structure itself. Fluids are flowing back and forth to provide coolingor lubrication during the drilling operation. Plus the application is measuringthe radioactivity of the formation around the unit, so there are many noisesources that need to be screened out," Chan says.

As faras the challenges on the component level, previously when drills only went upto 175C, existing silicon that was military rated could be stretched and usedin the application. The goal would be to see if the performance held up,characterize the stresses and subject the system to extensive testing.

"Goingfrom 175 to 210C is much harder because fewer components are available tohandle the higher temperatures," says Aparo. "This is one of the firstcomponents designed specifically for that elevated temperature range. We usedan SOI process and one of our ADI fellows with over 30 years of experience wasa part of our design team."

The resultingAD8229 amplifier is best-in-class in all three performance categories for high-temperatureapplications including CMRR (common mode rejection ratio), voltage offset andinput noise. CMRR performance is 100 dB over the temperature range of 55 to 210C. The AD8229 input voltage offsetvaries by only 100-nV/C over the entire temperate range. Input noise is1.0-nV/vHz making the amp ideal for sensors that read faint signals such asthose used in down-hole drilling, nuclear magnetic resonance spectroscopy andgamma ray detection.

Click hereto watch ADI Fellow Moshe Gerstenhaber explain how the AD8229 meets the designchallenges of high-temperature environments.

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