Low supply voltage bandgap reference circuit and method

摘要

A circuit and method for a bandgap voltage reference operating at 1 volt or below is disclosed, wherein the operational amplifier (A1) drives resistors (R2, R3) only so that both the flicker noise contribution and the process sensitivity due to the conventional metal oxide semiconductor (MOS) devices used as a current mirror within the proportional-to-absolute-temperature (PTAT) loop are eliminated. Two symmetric resistive divider pairs formed by (R1A/R1B, R2A/R2B) are inserted to scale down both the base-emitter voltages (VEB1, VEB2) of bipolar transistors (Q1, Q2) and the PTAT current (IPTAT) so that an output reference voltage (VREF) becomes scalable. Proper bias currents through transistors (M3, M4), which are used to bias (Q1, Q2) and (R1A/R1B, R2A/R2B) respectively, are produced by an additional V-I converter (319) using VREF itself, resulting in a final process, voltage and temperature (PVT) insensitive output reference voltage.

主权项

1. A voltage reference circuit for generating a reference voltage, comprising:
a voltage-to-current converter circuit configured to generate a first reference current and a second reference current; a first differential voltage divider configured to scale down a first base-emitter voltage of a first bipolar junction transistor biased by the first reference current to generate a first scaled base-emitter voltage; a second differential voltage divider configured to scale down a second base-emitter voltage of a second bipolar junction transistor biased by the second reference current to generate a second scaled base-emitter voltage; and a bandgap voltage reference circuit configured to generate a reference voltage by using the first scaled base-emitter voltage and the second scaled base-emitter voltage; wherein the bandgap voltage reference circuit comprises:
an amplifier configured as a voltage clamper to generate a scaled proportional-to-absolute-temperature (PTAT) current;a current buffer to supply the scaled PTAT current across a first feedback resistor and a second feedback resistor; anda summing circuit to add the first scaled base-emitter voltage into the scaled PTAT current multiplied by sum of a first equivalent resistance of the first differential voltage divider and the first feedback resistor, and the second scaled base-emitter voltage into the scaled PTAT current multiplied by sum of a second equivalent resistance of the second differential voltage divider and the second feedback resistor, respectively.