Digitally calibrated bandgap reference
AssigneeLSI Logic Corporation
InventorsGregory T. Uehara, Samuel Sheng, Cormac Conroy
Life of this patent
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Abstract
A system and method for compensating for a voltage offset between an inverting input and a noninverting input of an op amp to provide a stable bandgap reference. The method including measuring the voltage offset between the inverting input and the noninverting input of the op amp and searching for a compensating current input to the op amp that compensates for the voltage offset. A programmable current source is set to output the compensating current to the op amp.
Claims18
A compensated bandgap reference circuit comprising:
- an op amp having an inverting input and a noninverting input wherein the op amp is configured to output a bandgap reference based on base emitter voltage differences of a plurality of transistors;
- a digitally programmable current source configured to compensate for an offset voltage between the inverting input and the noninverting input;
- and
- a comparator configured to measure the offset voltage between the inverting input and the noninverting input and to digitally control the programmable current source.
A compensated bandgap reference circuit comprising:
- an op amp having an inverting input and a noninverting input, wherein the op amp provides a bandgap reference voltage output;
- a first transistor having a first emitter connected to the noninverting input of the op amp;
- a second transistor having a second emitter connected to the inverting input of the op amp;
- a comparator configured to measure a voltage offset between the inverting input and the noninverting input;
- and
- a digitally programmable current generator configured to inject a programmed compensating current into the op amp wherein the programmed compensating current is determined as a current that causes the comparator to measure the voltage offset to be less than a threshold.
A method of compensating for a voltage offset between an inverting input and a noninverting input of an op amp to provide a stable bandgap reference comprising:
- measuring the voltage offset between the inverting input and the noninverting input of the op amp;
- searching for a compensating current input to the op amp that compensates for the voltage offset;
- and
- setting a digitally programmable current source to output the compensating current to the op amp.
Dependencies are inferred from the claim text.