AnsweredAssumed Answered

AD620 oscillation with long cable drive

Question asked by ricky on Nov 12, 2013
Latest reply on Dec 19, 2013 by AnalogGround

Hello All,

My customer trying to drive long cable by AD620 In-Amp with attached circuit diagram.

He said he got oscillated output at around 500kHz oscillation frequency.

This circuit has been shipped on many units, however oscillation is occurred on recent board only.

In the attached circuit, 900-950pF is the cable capacitance of around 10m log cable.

The oscillation amplitude is around 3Vp-p, and around 500kHz.

When he disconnect the cable, then oscillation stopped.

When he changed the cable from 10m long to 6m long, then oscillation became around 2.1Vp-p and around 700kHz.

He would like to confirm that the oscillation is occurred by 900-950pF cable capacitance or not.

If the cable cause the oscillation, then could you advise how to solve the oscillation issue?

If the circuit should be stable with the 900-950pF load, could you suggest him what would be the cause of the problem

My SPICE simulator on my PC (NI multisim component evaluator 13.0 Analog Devices edition) doesn’t work well, so I would like to ask your help

Thank you for your help.

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