I am attempting to build an audio amplifier that accepts an arbitrary stereo input signal via a 3.5mm connector. My objective is to convert that single-ended input into a balanced AND differential signal so that I can run it through a Texas-Instruments TPA6120A2 configured in differential mode.

The issue is that I am having difficulty understanding how I should implement the audio transformer circuit. I assume I should use a 1:1 audio transformer but how does this get wired up? Also, I believe that an inductor needs to be used in the converter circuit. Does anyone have an example circuit?

More specifically, I can't find any requirements for input impedance for the TPA6120A2. How can I match a typical input impedance on the balanced side of the transformer? Could you provide examples?


You shouldn't need a transformer. Page 10 of the data sheet shows how the device can be configured for single-ended operation: -

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If you look at page 1 of the datasheet you'll see that the op-amp symbol above is inside the device but you'll need to choose the resistors such as 1k for Rf and Ri.


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