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US 9,310,823 B2Granted
Voltage reference
AssigneeTexas Instruments Incorporated
InventorsXiao Pu, Krishnaswamy Nagaraj, Yue Hu
Life of this patent
Estimating the term…
Abstract
A voltage reference circuit includes a bipolar transistor and a circuit configured to measure the ratio of emitter current to base current of the bipolar transistor. The output voltage of the voltage reference circuit is compensated as a function of the measured ratio.
Claims8
A voltage reference circuit having an output voltage, the circuit comprising:
- a bipolar transistor having a base and an emitter;
- a circuit configured to measure the ratio of emitter current to base current of the bipolar transistor;
- the output voltage being compensated as a function of the measured ratio;
- the bipolar transistor being a third bipolar transistor, the circuit further comprising:
- first and second bipolar junction transistors having different current densities;
- where the third bipolar junction transistor is driven with the same current density as one of the first and second bipolar junction transistors;
- where the third bipolar transistor is alternately driven with the current density of the first bipolar transistor and the current density of the second bipolar transistor.
4 more elements
A voltage reference circuit having an output voltage, the circuit comprising:
- a bipolar transistor having a base and an emitter;
- a circuit configured to measure the ratio of emitter current to base current of the bipolar transistor;
- the output voltage being compensated as a function of the measured ratio;
- further comprising:
- an integrating analog-to-digital converter (ADC), the integrating ADC charging a capacitance for a first time period with the emitter current of the bipolar transistor, and discharging the capacitance for a second time period with the base current of the bipolar transistor, and where the ratio of emitter current to base current of the bipolar transistor is proportional to the ratio of the first time period to the second time period.
2 more elements
A method, comprising:
- measuring, by a circuit, the ratio of emitter current to base current of a bipolar transistor;
- and
- trimming, by a processor, a first resistance in a voltage reference circuit, to adjust an output of the voltage reference circuit as a function of the measured ratio;
- the step of measuring further comprising:
- switching, by the circuit, emitter current in the bipolar transistor, so that the ratio of emitter current to base current is measured for a plurality of current densities.
2 more elements
Dependencies are inferred from the claim text.