A Novel Low-Noise Bandgap Reference with an Active RC Filter

A high-area efficiency and low-output noise bandgap reference (BGR) circuit is proposed in this study. Compared with the passive low-pass RC filter with a large-area capacitor in conventional BGR circuit, an active low-pass RC filter with a significantly area-efficiency capacitor and a large equivalent resistor is proposed in this study, where the large equivalent resistor is achieved by using an ultra-low-power currentmirror circuit. Due to the proposed active filter, BGR circuit with an output capacitor of just 10 pF obtains the similar noise flowing compared with the traditional BGR circuit using a passive filter with an output capacitor of 1000 pF. The proposed BGR circuit implemented in a standard 0.5-μm CMOS process and with a total current of 14 μA at a supply voltage of 5 V, shows an output reference voltage of 1.25 V, a temperature coefficient (TC) of 5 ppm/ °C with a temperature range from - 40-125°C, and an approximate squared output noise as low as 1.45E - 14 V
²
/Hz when the frequency is higher than 5 kHz.