Auto-Calibration Technique for Current-Based Bandgap Voltage Reference

For the industrial application, the bandgap voltage reference (BGR) requires calibration after fabrication to ensure accuracy [1–3] which may lead to expensive labor costs. Some BGRs in the literature were reported without trimming [4,5], however, their output voltages will drift due to device aging and stress [6]. The proposed auto-calibration technique can eliminate such a process thus saving costs. Furthermore, the $\beta$ of the BJT is small in the advance process such that the variation of $\beta/(\beta+1)$ in $V_{EB}=(kT/q)\ln[(I_{E}/I_{S})\beta/(\beta+1)]$ has a great influence on VEB, resulting in residual temperature coefficient (TC) variation after the conventional one-point trimming. This implies an error in the output, thus reduce stability and lifetime of the system.