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基于0.18μm CMOS工艺,设计了一种16位600 MS/s电流舵D/A转换器。该D/A转换器为1.8V/3.3V双电源供电,采用并行输入、差分电流输出的四分段(5+4+3+4)电流舵结构。采用灵敏放大器型锁存器可以精确锁存数据,避免出现误码;由恒定负载产生电路和互补交叉点调整电路组成的同步与开关驱动电路,降低了负载效应引起的谐波失真,同时减小了输出毛刺;低失真电流开关消除了差分开关对共源节点处寄生电容对D/A转换器动态性能的影响。Spectre仿真验证结果表明,当采样频率为625MHz,输入信号频率为240MHz时,该D/A转换器的SFDR为78.5dBc。
Based on a 0.18μm CMOS process, a 16-bit 600 MS / s current steering D / A converter is designed. The D / A converter is a dual 1.8V / 3.3V power supply with a four-stage (5 + 4 + 3 + 4) current steering structure with parallel input and differential current output. The use of sense amplifier latch can accurately latch the data to avoid errors; by the constant load generating circuit and the complementary cross-point adjustment circuit composed of synchronous and switching drive circuit, reducing the load effect caused by the harmonic distortion, while reducing The output glitch; low distortion current switch eliminates the differential switch on the common source node parasitic capacitance on the D / A converter dynamic performance. Specter simulation results show that the SFDR of the D / A converter is 78.5dBc when the sampling frequency is 625MHz and the input signal frequency is 240MHz.