A noise-shaped direct digital IF to RF DAC (DIF2RF) with embedded
up-converter mixer is presented. The digital IF signal is noised shaped
by a band-pass .SIGMA..DELTA. modulator with a single bit IF output
followed by a semi-digital current-mode IF filter to attenuate
out-of-band quantization noise. A current steering DAC combines scaled
values of local oscillator (LO) signals as current sources for performing
current steering and upconversion in a single cell.