Voltage reference circuit, integrated circuit, and method for generating a reference voltage

A method for generating a reference voltage, the method comprising:

• providing a supply voltage to one end of a resistor string;
• providing, by a first portion of the resistor string, a first feedback voltage to input terminals of a first asymmetric differential amplifier comprising two transistors with different threshold voltages as a differential pair;
• providing, by a second portion of the resistor string, a second feedback voltage to input terminals of a second asymmetric differential amplifier comprising two transistors with different threshold voltages as a differential pair;
• amplifying, by the first asymmetric differential amplifier, the first feedback voltage to provide a first partial reference voltage across the first portion of the resistor string;
• amplifying, by the second asymmetric differential amplifier, the second feedback voltage to provide a second partial reference voltage across the second portion of the resistor string;
• and
• providing, at an output of the first or the second asymmetric differential amplifier, the reference voltage as a sum of the first partial reference voltage and the second partial reference voltage.

A voltage reference circuit comprising:

• a first asymmetric differential amplifier and a second asymmetric differential amplifier, each comprising two transistors with different threshold voltages as a differential pair;
• and
• a resistor string arranged between an output of the first asymmetric differential amplifier and a supply terminal, the resistor string comprising a first portion, a second portion and a connecting circuit node interposed between them,
• wherein an output of the second asymmetric differential amplifier is coupled to the connecting circuit node,
• wherein the first portion of the resistor string is configured to provide a first feedback voltage that is fed back to input terminals of the first asymmetric differential amplifier, and the second portion of the resistor string is configured to provide a second feedback voltage that is fed back to input terminals of the second asymmetric differential amplifier,
• wherein the voltage reference circuit is configured to provide a reference voltage at the output of the first asymmetric differential amplifier or the second asymmetric differential amplifier, and
• wherein a temperature coefficient of an offset voltage of the first asymmetric differential amplifier has an opposite sign to a temperature coefficient of an offset voltage of the second asymmetric differential amplifier and/or
• wherein offset voltages of the first asymmetric differential amplifier and the second asymmetric differential amplifier are uncorrelated.