Bandgap Voltage VGO Extraction with Two-Temperature Trimming for Designing Sub-ppm/°C Voltage References

This paper presents a general approach to extract VGO from the base emitter voltage of a bipolar transistor. VGO is the silicon bandgap voltage at zero Kelvin and it is a physical constant voltage independent of temperature. The proposed method can be implemented on any of the widely used Banba, Kuijk, Brokaw or resistorless structures to build voltage references with sub-ppm/°C temperature coefficient. One embodiment based on Kuijk structure is used to illustrate how the proposed VGO extraction can be realized. Error sources which can affect the voltage reference's performance are analyzed with a new base expansion and their effects on the temperature coefficient are minimized after the proposed two-temperature trimming. Transistor level simulations are run in GlobalFoundries 130nm process and simulation results show that the design can achieve 0.5 ppm/°C temperature coefficient from −40 °C to 125 °C.