At the moment, I'm working on converting a single ended audio signal to a differential one (source is a CS42L55, need a differential input for a CSR8670. The latter's datasheet is indecisive about how to approach this issue). I have a few options, and I'm wondering about the validity of each.
- Tie the negative differential input to analog ground
- Use an op-amp to create an inverse signal
- Use a transformer (I've only just read about this, not sure how it works yet)
This got me thinking - why does a differential signal need an inverse input, if the noise on both cables is the same?
For example (all waves start from 0v):
/\ Positive input: / \ Negative input (neutral) : ----
If the same waves had noise, like this for example:
__ Positive input: / \ _ _ Negative input (neutral): \/
Therefore, pos - neg = pos without noise right? (the sum being the function of the converter?) Is there a benefit to using an inverse wave instead of ground (op-amp > just tying to gnd?)
I guess I am missing something here, and I'd like to know what.