Two-temperature trimming for a voltage reference with reduced quiescent current

A method for trimming a voltage reference circuit, the method comprising:

• setting a temperature of the voltage reference circuit to a first temperature;
• trimming first and second resistors to set a current through a differential amplifier stage and a scaling amplifier stage, wherein the differential amplifier stage includes the first resistor, and the scaling amplifier stage includes the second resistor;
• trimming a third resistor to set an output voltage to a target voltage at the first temperature, wherein the third resistor is included in the scaling amplifier stage;
• setting the temperature of the voltage reference circuit to a second temperature;
• and
• trimming a fourth resistor by a value of P1 to set the output voltage to the target voltage, wherein the fourth resistor is included in the differential amplifier stage.

A measurement system comprising:

• a voltage reference circuit having a reference input and a reference output, wherein the reference input is coupled to an input voltage terminal, and the voltage reference circuit is configured to provide a reference voltage at the reference output;
• a sensor having a sensor input and a sensor output, wherein the sensor input is coupled to the reference output, and the sensor is configured to provide an analog measurement signal at the sensor output proportional to the reference voltage;
• and
• an analog to digital converter (ADC) having an ADC input and an ADC output, wherein the ADC input is coupled to the sensor output, and the ADC is configured to provide a digital signal proportional to the reference voltage;
• in which the voltage reference circuit includes:
• a differential amplifier stage including first and second resistors, the differential amplifier stage configured to provide a control signal;
• and
• a scaling amplifier stage coupled to the differential amplifier stage and including third and fourth resistors, wherein the scaling amplifier is configured to provide the reference voltage at an output port responsive to the control signal;
• wherein:
• the first and third resistors are trimmable to set a current through the differential amplifier stage and the scaling amplifier stage at a first temperature,
• the fourth resistor is trimmable to set a voltage at the output port to the reference voltage at the first temperature, and
• the second resistor is trimmable to set the voltage at the output port to the reference voltage at a second temperature.