Piecewise BJT process spread compensation exploiting base recombination current

In this paper, a piecewise bipolar junction transistor (BJT) process spread compensation scheme is presented. By exploiting the strong correlation between the BJT saturation current and the piecewise base recombination current, the process spread and proportional-to-absolute-temperature (PTAT) drift of the base-emitter voltage (Vbe) can be reduced over a wide temperature range. Fabricated in standard 0.18-μm CMOS, the chip prototype achieves a measured Vbe standard deviation (STD) of 1.1 mV (1.8 mV) from -30 to 60 °C (-30 to 120 °C) over 12 samples, corresponding to a 2.9X (1.8X) improvement when compared to the measured Vbe STD of 3.24 mV at 25 °C from 15 standalone BJT samples with constant external bias current using the same process.