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I need to convert the output of differential output DAC to single ended. It's a 2 Vpp signal with a 1 V common-mode output. The output is 100 ohms. Should I use a transformer or a instrumentation amp. to do this conversion? The output could be up to 10 MHz (it's a communication signal) and the power is < -10 dBm.

Update 1 Since the signal is a RF communications signal, there is no DC component.

Update 2 Avoiding a +/- power supply would be nice, so in that case, a transformer would be better, correct?

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    \$\begingroup\$ Why not use a line receiver instead? Like the MAX4444/MAX4445, it has a BW of 90MHz 0.1dB or 550MHz -3dB bandwidth. \$\endgroup\$ – Hans Feb 24 '11 at 22:35
  • \$\begingroup\$ Isn't there an example schematic in the datasheet? \$\endgroup\$ – endolith Feb 25 '11 at 0:14
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I think, depending on the specifics of the datasheets, that the transformer will give you a better BW, and galvanic isolation, if you like that. I think Analog Devices has some slick isolators based on transformers packaged into normal IC packages.

INAs could work, but you might want to bias your signal up a bit to get it off the ground power rail (assuming you don't just reference it and use a dual supply), for better performance. That might not be true so much anymore, but it sure used to be.

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As a crazy solution you may move ground&supplies of your DAC 1v higher. In this case you will get your shifted signal without any distorsions.

Level-converting of digital signals is much easier, does not intoduce analog error, and sometimes is not needed.

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Instrumentation amp. The transformer won't work if the signal is static.

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  • \$\begingroup\$ Brian, thanks for the answer. Since this is a communications signal, there's no DC component. \$\endgroup\$ – gallamine Feb 25 '11 at 12:57

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