A 14-Bit 3-GS/s DAC Achieving SFDR >63dB Up to 1.4GHz With Random Differential-Quad Switching Technique

This brief analyzes the data-dependent switching distortion and the image tone in the current steering digital-to-analog converter (DAC). A switching scheme called random differential-quad switching (RDQS) is presented. This RDQS technique adopts two pairs of differential switches and randomizes the selection of the two pairs. Thus the data-dependent switching distortion and the image tone caused by the mismatch between the two pairs of differential switches are disturbed. With the RDQS technique and a specially designed switching signal generator, a 14bit 3GS/s current-steering DAC is implemented in 40nm CMOS technique. Measurements show that this DAC achieves spurious free dynamic range over 63dB and suppresses the image tone by 15dB. This DAC occupies 0.9mm
²
and consumes 190 mW at 1V/2.5V supply.