A 16-bit 1GSPS current-steering digital-to-analog converter(DAC) is proposed. The DAC employed a 7+4+5 segmented architecture. The full-scale current output was 20mA with 1.8V/3V dual power supply. A special Quad Switch circuits, voltage-limited switch driver circuits, current source with two cascade nmos, logic decoder were designed to achieve excellent specification. The SFDR is higher than 78.06dB at 1GSPS and 101.07MHz signal frequency.