为设计应用于现代宽带无线通信系统中的具备高动态性能的高速电流舵数据转换器(DAC)接口电路,首先针对"电流舵DAC中由非理想的电流开关转换引入的动态非线性误差导致输出谐波失真"的机理进行了理论分析和公式推导,得到了实际电流舵DAC电路参数及编码方式与DAC输出信号谐波失真幅值之间的量化关系.然后在Matlab中建立了电流舵DAC的行为级模型用于评估非理想开关转换及编码方式对输出信号动态无杂散范围(SFDR)指标的影响.设计了一个12位电流舵DAC电路用于验证该行为级模型的有效性.通过分析模型的仿真结果,得到了具有重要的电路设计指导价值的结论.%The challenge has been imposed on the circuit designers to come up with a high speed current-steering digital to analog converter (DAC) with high dynamic performance which is widely used in broad-band wireless communication systems.The non-ideal switching behavior of the current switch is the important source of the dynamic error which results in great harmonic distortion in current-steering DAC.This phenomena was analyzed and deduced to achieve a formula to describe the relationship among amplitude of harmonic distortion, parameters of the designed DAC circuit and the employed encoding scheme.A behavioral model of current-steering DAC was built in Matlab to estimate the impact of the non-ideal switching behavior on DACs spurious-free dynamic range(SFDR).The model was verified by comparing the simulation results of behavioral model with that of a 12-bit transistor-level current-steering DAC circuit.Simulation results of behavioral model were analyzed to acquire important guide line for current-steering DAC circuit design.
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