Apparatus, and a related method, for converting digital signals directly to radio-frequency (RF) analog signals. The apparatus includes a single high-speed delta-sigma modulator and an integrated upsampler that increases the data rate of digital input samples by a selected factor, such as nine times. The delta-sigma modulator is configured to include a feedback multiplier coefficients that are selected to greatly facilitate operation of associated adders. At least one critical adder includes a carry-select adder modification that further speeds up the add operation and ensures that the apparatus operates at desirably high frequencies.

 
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> Direct conversion receiver having a subharmonic mixer

~ 00329