A Zener-Based Voltage Reference Design Compensated Using a ΔVBE Stack

Abstract

Two temperature insensitive voltage reference types are widely used today, namely buried Zener and bandgap voltage. Reference voltages based on buried Zener diodes are less sensitive to stress and have lower Long Term Drift (LTD) (approx. 3ppm/1kh), but require a minimum supply voltage of at least 6.5V. Bandgap-type voltage references can operate off supply voltages as low as 1V. However, they have larger LTD compared to buried Zener type references (typically $< \pmb{30}\mathbf{ppm}/\pmb{1}\mathbf{kh})$. Further enhancements to the architectures presented in [1] and [2] are discussed in this paper. By using a high performance monolithic deep buried Zener and replacing the embedded one, further performance enhancements in the form of lower Re-Flow drift, reduced LTD, better noise and improved linearity characteristics are obtained. Maintaining the overall circuit performance achieved in [1] and [2] of TC approx. 1.5ppm/°C, and max nonlinearity better than ~1mV over the full temperature range from − 40 to 125°C are two critical requirements.