Design of a trimmed current reference with a low temperature drift
Yongqian Du · Journal of Xidian University · 2013
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 15 μA to 80 μA 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%·Iref～14.3%·Iref and 0.11%·Iref,respectively.The circuit could be applied to high precision A/D and D/A converters.