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Old 29th April 2005, 04:30 PM   #1
00940 is offline 00940  Belgium
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Default D1 I/V, balanced dac, unbalanced output

Many dac chips today offer a balanced current out. Practically speaking, many among us only need unbalanced out. One thing I don't like that much about the D1 is the need for a costly output capacitor. Could I simply add a INA134 balanced to unbalanced converter after the D1, bypassing the output caps ? There's a possibility to null offset with the ina134. Matching all the parts of the I/V stage would in theory make the offset rather low.

Something obvious I'm missing here before I order the parts ?
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Old 29th April 2005, 10:59 PM   #2
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With the default circuit of the D1 the inputs to the 134 (as in your circuit w/o the FET follower) would be around 17V DC, which is a little too close to the 18V max rail of the 134 it would seem. You'd have to tweak the D1 V+ or change R values to get that DC down to where the 134 could deal with it.

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Old 30th April 2005, 12:12 AM   #3
00940 is offline 00940  Belgium
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Doesn't the INA134 easily support such common-mode input voltage ? I joined the interesting parts of the datasheet below. According to it, the INA134 admits at its input 2X(V+)-4 (for a 0V output). It is thus 32VDC, no ? The graph joined seems to indicate that for an output signal of roughly 2V, I can almost get a 30VDC input.

Here's the datasheet : http://focus.ti.com/lit/ds/symlink/ina134.pdf
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