用于高速DDS中电流舵DAC的基准电流源设计

摘要

A reference current source circuit for the current-steering DAC in the high speed DDS( Digital Direct Fre-quency Synthesis)was introduced,as foundation of the traditional reference current source circuit,the base of the two triodes were connected which produced the△VBE ,and then two amplifiers,were added to make the collector and the base clamp at the same potential. So the transistors in the condition of the saturation region to delete the error Vos that caused by the offset of the amplifiers. The VOS was eliminated in the reference current source circuit. In addition,a circuit for compensating the nonlinear term that is in the expression of VBE to T is proposed. Fabricated by 0. 18 μm N-wells 1P5M process,the NPN type triodes were used. Results showed that in the condition of tt,the tem-perature coefficient of reference output voltage was 10í10-9/℃, the temperature coefficient of reference output current was 10í10-9/℃.%介绍一种用于高速DDS中电流舵DAC的带隙基准电流源电路,在传统带隙基准源电路的基础上将产生△VBE的两个三极管基极相连,使用两个运放分别将其集电极与基极钳至于相同电位,在保证三极管处于饱和区的基础上消除传统基准电路中由运放失调带来的误差VOS,通过温度补偿电路,补偿VBE与温度T的非线性项。电路采用0.18μm的深N阱1P5M工艺,选用NPN型三极管,仿真结果表明tt条件下基准电压输出温漂系数抑10×10-9/℃,基准电流输出温漂系数抑10×10-9/℃。