A process and temperature compensated current reference circuit in CMOS process

摘要

A novel current reference circuit that compensates for process and temperature variations without any extra trimming is proposed in this paper. Four thousand Monte Carlo simulations show that the maximum % error (deviation from the desired value) in the reference current is ± 5.07% considering process variations (die-to-die, wafer-to-wafer and batch-to-batch). Considering process variations and temperature change from 0 ℃ to 100 ℃ both, the maximum error in the reference current is + 8.56%. The proposed circuit has been fabricated in 180 nm CMOS process. Measurement results on 50 dice at room temperature show that the mean of the proposed reference current is 9.39% away from its designed value. Mean of drain current of a fixed biased MOSFET fabricated in the same run is 35.41% away from its designed value. Measurements at four different temperatures, 27 ℃, 50 ℃, 75 ℃ and 100 ℃, on these dice show that the maximum error in the reference current is 17% whereas that in the drain current of a fixed biased MOSFET is 126%. In other words, the proposed current reference circuit reduces the maximum error by a factor of 7 (from 126% to 17%) when process and temperature variations both are considered without trimming. With a simple trimming circuit the maximum variation in the reference current is reduced to ±3.17%