Re: Why can't we do quatrature upconversion in digital circu
You can certainly do this, but it's not really practical.
To get a fully modulated signal, you need to have the DAC output at an IF frequency. Now you are faced with dealing with image rejection in your transmit chain, which makes the design more complicated. To increase the DAC output frequency high enough to make the image frequency easy to deal with will push the DAC clock rate high enough that the current is too much to deal with.
Dave