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adding variable gain to AD8222

Question asked by L3engineer on May 21, 2012
Latest reply on May 22, 2012 by ScottH

I am wanting the ability to switch in a gain at power-up and am considering using a ADG1414 serially-controlled octal SPST switch to be the switch since I am I/O limited. The gain of the instrumentation amp will either be one or a specific other value and will not be switched dynamically. The AD8221 mentioned keeping the traces to the gain resistor as short as possible due to parasitic inductance and since this part is a dual ad8221 then I assume the same rule applies. The question is can an octal SPST switch be used with the AD8222 and then the gain resistor just be trimmed to compensate for parasitics? I understand that there will be drift errors associated with the switch however I am just wanting to know the gotchas from using an octal switch.

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