一种可校准的低温漂基准电流源

Design of a trimmed current reference with a low temperature drift

针对由于工艺偏差导致的器件误差和不匹配性会严重降低基准源的性能,在研究器件失配的基础上,设计了幅值在15～80μA之间可调的基准电流源Iref,同时利用温度补偿电路来提高其温度特性.为了进一步提高基准源的精度,提出了一个双向校准电路,它由8bit的外部信号控制校准电流的方向及大小,并采用二进制加权的编码方式实现127级的等比数列电流校准.基于CMOS 0.13μm工艺,在输出电流为15μA,温度范围为-40℃～120℃的仿真条件下,基准电流温度系数为26ppm/℃.实测结果表明,电流源校正范围为-14.3%.Iref～14.3%.Iref,校正精度为0.11%.Iref,可应用在高精度的A/D和D/A转换器等集成电路中.

Component tolerances and mismatches due to process variations severely degrade the performance of bandgap reference circuits. Based on device mismatch models, a current reference Iref with adjustable output current from 15μA to 80μA is designed. A compensated circuit is used to reduce the temperature drift. To achieve more accurate current reference, an 8 bit bi-directional trimming array with 127 current levels is proposed. This digitally programmable array is binary weighted for accuracy and flexibility. Simulation shows that the temperature coefficient is 26 ppm/℃ over the wide range of -40℃ to 120℃ when the output current is 15 μA. Based on the CMOS 0.13 μm technology, the measurement results show that the trimmed range and precision for current reference are -14.3%. Ire～ 14. 3% ·Iref and 0.11%· Iref, respectively. The circuit could be applied to high precision A/D and D/A converters.