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AD8307 DC Operation

Question asked by ashwmk on May 19, 2017
Latest reply on May 19, 2017 by jdobler

I'd like to use the AD8307 to produce an output voltage proportional to the log of an input signal, including its DC component. It is claimed that the amplifier works from DC to 500 MHz, but for the most part revision E of the datasheet (which I presume is the latest) discusses applications for which the inputs are AC coupled. On page 15 under the heading 'Offset interface' reads: 'If true dc coupling is needed, down to very small inputs, this automatic loop must be disabled and the residual offset eliminated using a manual adjustment,' but I no further discussion or related schematics are given. I have found revision C of the datasheet with a section that specifically discusses DC coupled inputs, however I don't know how useful it is given that it was omitted in the latest version. Is it really possible to DC couple an input signal to the AD8307, or are there other options that I ought to consider?

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