A Comparative Study of Voltage Reference Generation Techniques for Low-Voltage Micropower Management Circuits

In this paper, a comparative analysis is performed between two techniques previously presented in the literature for generating voltage references (VREF), focusing on their stability with respect to variations in temperature and process parameters, in the context of integrated micropower management circuits. The first technique combines Proportional-to-Absolute-Temperature (PTAT) and Complementary-to-AbsoluteTemperature (CTAT) currents generated with the support of operational amplifiers, to generate the (VREF). The second technique utilizes a self-biased current mirror for generating a PTAT current, while the CTAT current is again generated with the previously used opamp-based circuit, and both currents are added to generate the VREF. A band-gap reference (BGR) design involves a bandgap core, a summing circuit, and a start-up circuit to apply the correct bias. Both BGR1 and BGR2 circuitry provides a voltage reference of 900 mV over-40 °C to 100 °C temperature range with a power supply (VDD) of 1.2 V.