Design of a full-swing CMOS current steering D/A converter with an adaptive high-impedance current cell

This paper describes a 6-bit full-swing CMOS current-steering digital-to-analog converter (D/A converter, DAC). Conventionally, current-steering DAC does not have a full swing analog signal, because they have an inevitable voltage drop with the output current cell. To overcome the drawbacks, a new scheme of adaptive output current cell composed of both nMOS and pMOS is proposed. Using a pMOS current cell and a nMOS current cell, the final output voltage is driven by a multiplexer which selects the optimized current cell. Both of the current cells are added at the multiplexer adaptively. A 6-bit current steering DAC has been fabricated with 0.11 µm CMOS technology to verify the performance of the full-swing DAC. From the measured results, we obtain that the DAC has a full-swing output signal.