US 5,440,305 A · Method and apparatus for calibration of a monolithic voltage reference

Abstract

A method and apparatus for calibration of errors in a monolithic reference includes a bandgap voltage reference (50) that outputs an untrimmed voltage and a temperature voltage. The untrimmed voltage and temperature voltage are input to a delta-sigma A/D converter (52) which has the output thereof processed through a digital filter (54) to output data on a data bus (58) for storage in an EEPROM (60). The EEPROM (60) is operable in one mode to store temperature history data and, in another mode, to store temperature compensation data. In one mode, temperature compensation parameters are retrieved from the EEPROM (60) and utilized by a multiplier/accumulator circuit (74) to generate compensation factors which are output as a digital word to a DAC (76) for controlling a trim circuit (14). The trim circuit (14) provides a temperature compensation for the output of the bandgap voltage reference (50). The system is operable in a calibration mode to measure temperatures during a burn-in procedure and calculate necessary information to determine compensation factors and store these in the EEPROM ( 60). This temperature data is extracted from the EEPROM (60) and output to a serial I/O port (64), compensation factors determined and then stored back in the EEPROM (60). The delta-sigma A/D converter (52) in the run mode then makes temperature measurements for use by the multiplier/accumulator circuit (74) in determining the appropriate compensation data to extract from the EEPROM (60) to trim the output of the bandgap voltage reference circuit (50).

Claims30

Dependent claims

A monolithic compensated voltage reference, comprising:

a reference voltage generator for generating an uncompensated analog voltage;
an analog environmental parameter measuring device co-located with said reference voltage generator for measuring predetermined environmental parameters associated with said reference voltage generator, and for generating an analog environmental signal corresponding to the measured environmental parameters;
an analog-to-digital converter for convening said analog environmental information to a digital environmental signal, said analog-to-digital converter operable to take the ratio of the output of said environmental parameter measuring device and an internal voltage reference that is co-located with said reference voltage generator;
a non-volatile memory for storing digital compensation parameters associated with said digital environmental information;
a compensation processor for selecting said digital compensation parameters from said memory corresponding to said digital environmental information output by said analog-to-digital converter, said processor operable to process said selected digital compensation parameters in accordance with a predetermined compensation algorithm to output a digital compensation word that corresponds to analog environmental information;
and
a compensation circuit for receiving said digital compensation word and compensating said uncompensated analog voltage in accordance with the value of said digital compensation word.

4 more elements

An monolithic voltage reference with continuous compensation, comprising:

a reference voltage generator for generating an uncompensated analog voltage on the output thereof;
an environmental parameter measuring device co-located with said reference generator for measuring predetermined environmental parameters associated with said reference voltage generator, and for generating an analog environmental signal corresponding to the measured predetermined environmental parameters that are proportional to corresponding absolute environmental parameters;
an analog-to-digital converter for converting said analog environmental signal to a digital environmental signal;
a non-volatile memory for storing digital correction parameters associated with each value of said digital environmental signal;
a compensation processor for retrieving select ones of said digital compensation parameters from said memory, said select digital compensation parameters corresponding to said digital environmental signal output by said analog-to-digital converter, said processor operable to process said select digital compensation parameters in accordance with a predetermined compensation algorithm to output a digital compensation word;
a compensation circuit for receiving the digital compensation word and compensating said uncompensated analog voltage in accordance with the value of said digital compensation word;
and
test control circuitry for controlling said analog-to-digital converter to measure the response of said uncompensated analog voltage as a function of the environmental parameters at a plurality of values of the environmental parameters to output for each measured value of the environmental parameters a digital environmental signal and an associated digital error voltage signal and store at each measured value of the environmental parameters said associated digital environmental signal and digital error voltage signal in said memory, said digital error voltage signal operable to be converted into said compensation parameters for each of said digital environmental signals.

5 more elements

A method for compensating an uncompensated analog voltage output from a monolithic reference voltage generator to provide a compensated analog output voltage, comprising the steps of:

measuring predetermined environmental parameters associated with the reference generator in the proximity thereof and generating an analog environmental signal corresponding to the measured predetermined environmental parameters;
convening the analog environmental signal to digital environmental signal through an analog-to-digital converter by processing the analog environmental sign al and an internal voltage reference that is co-located with the reference voltage generator to provide the ratio thereof as the digital environmental signal;
storing in a non-volatile memory digital compensation parameters associated with the digital environmental signal;
selecting the digital compensation parameters from the memory corresponding to the digital environmental signal generated by the step of converting;
processing the digital compensation parameters in accordance with a predetermined compensation algorithm to output a digital compensation word;
and
compensating the uncompensated analog voltage in the analog domain by a value corresponding to the value of the digital compensation word.

4 more elements

A method for compensating the uncompensated analog output voltage of a monolithic reference voltage generator to provide a compensated voltage output, comprising the steps of:

generating the uncompensated analog voltage with the reference voltage generator;
measuring predetermined environmental parameters associated with the reference generator in the proximity thereof and generating an analog environmental signal corresponding to the measured predetermined environmental parameters;
converting the analog environmental signal to a corresponding digital environmental signal with an analog-to-digital converter;
storing digital compensation parameters corresponding to each value of the digital environmental signal in a non-volatile memory;
retrieving select ones of the digital compensation parameters from the memory, the select digital compensation parameters corresponding to the digital environmental signal generated by the step of converting;
processing the select digital compensation parameters in accordance with a predetermined compensation algorithm to output a digital compensation word;
compensating the uncompensated analog voltage in the analog domain in accordance with the value of the digital compensation word to provide the compensated analog output voltage;
measuring the response of the uncompensated analog voltage output by the reference voltage generator as a function of the predetermined environmental parameters at a plurality of values of the predetermined environmental parameters and outputting for each measured value of the predetermined environmental parameters a digital environmental signal and an associated digital error voltage signal;
and
storing at each measured value of the predetermined environmental parameters, the associated digital environmental signal and digital error voltage signal in the memory, the digital error voltage signal operable to be convened into the compensation parameters for each of the digital environmental signals.

7 more elements

A method for calibrating the analog output voltage of a monolithic reference voltage generator comprising the steps of:

disposing the reference voltage generator at a first temperature;
changing the temperature of the reference generator from the first temperature to a second temperature;
measuring the analog output voltage of the reference voltage generator at a plurality of temperature measurement points between the first and second temperatures as the temperature of the reference generator traverses between the first and second temperatures;
generating a digital error signal representing the temperature error in the analog output voltage of the reference voltage generator at each of the plurality of temperature measurement points in accordance with a predetermined error measurement algorithm;
generating a digital temperature signal for each of the temperature measurement points having a value corresponding to the temperature;
and
storing in a non-volatile memory the digital error signal in conjunction with the digital temperature signal at the associated temperature measurement points for each of the temperature measurement points.

4 more elements

Dependencies are inferred from the claim text.

Method and apparatus for calibration of a monolithic voltage reference

Life of this patent

Method and apparatus for calibration of a monolithic voltage reference

Life of this patent

Abstract

Claims30