In this paper, an improved self-biased bandgap reference (BGR) with high power supply rejection ratio (PSRR) is presented. An operational amplifier constructing feedback loop is multiplexed with the generation of positive temperature coefficient (TC) voltage for lower power consumption, where an offset voltage is adopted to achieve proportional to absolute temperature (PTAT) voltage. With the temperature-independent reference generation, two feedback loops are realized at the same time for PSRR enhancement, which form a local negative feedback loop (LNFL) and a global self-biased loop (GSBL). The proposed BGR is implemented in a 180 nm BCD technology, whose results show that the generated reference voltage is 2.506 V, and the TC is 25 ppm/°C in the temperature range of -55 to 125 °C. The line sensitivity (LS) is 0.08 ‰/V. Without any filter capacitor, the PSRR is 76 dB at low frequencies, over 46 dB up to 1 MHz.
Keywords: Global self-biased loop; High power supply rejection ratio; Local negative feedback loop.