Improved DAC driving scheme for OFDM applications

Presented is a ´Redundant Signed Digit´ driving scheme for binary weighted D/A conversion. This scheme retains the simplicity of conventional binary weighted D/A conversion, but has greatly improved robustness with regard to parasitic effects, especially when processing signals with a high crest factor. Such signals occur in communication systems that use, e.g. orthogonal frequency-division multiplexing (OFDM). In this case an improvement of 9 dB in Missing Tone Power Ratio performance was measured on a prototype 250 MSample/s circuit implemented in 0.18 μm CMOS.