A 14 Bit 500 MS/s CMOS DAC Using Complementary Switched Current Sources and Time-Relaxed Interleaving DRRZ

A 14 bit 500 MS/s current-steering digital-to-analog converter (DAC) was designed and fabricated in 0.13 μm CMOS process. For traditional wide-band current-steering DACs, the spurious-free dynamic range (SFDR) is limited by nonlinear distortions from the code-dependent load variations and the code-dependent switching glitches. They are analyzed in this paper and mitigated by the proposed complementary switched current sources (CSCS) and time-relaxed interleaving digital- random-return-to-zero (TRI-DRRZ), respectively. The proposed techniques are fabricated and measured, with an SFDR of 84.8 dB at 11 MHz signal frequency and 73.5 dB at 244 MHz. The DAC consumes 299 mW from a mixed power supply of 1.2 V and 2.5 V with an active area of 1.85×0.65 mm
²
.