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US 2019/0379336 A1Published application
Methods and apparatus for driver calibration
AssigneeSemiconductor Components Industries, LLC
InventorSeiji TAKEUCHI
Life of this patent
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Abstract
Various embodiments of the present technology may comprise methods and apparatus for driver calibration. The methods and apparatus may comprise various circuits and/or systems to minimize an offset output current (e.g., a drive current) due to an offset voltage in an operational amplifier. The methods and apparatus may comprise a current comparator circuit and a replica circuit that operate in conjunction with each other to monitor the drive current and provide a feedback signal, which is then used to adjust the drive current and improve the accuracy of the drive current.
Claims20
A driver calibration circuit, comprising:
- a current comparator circuit responsive to a bias voltage and generates a threshold current;
- a controller connected to the current comparator circuit and configured to generate:
- a DAC code;
- and
- a calibration code;
- a digital-to-analog converter (DAC) connected to the controller and configured to generate:
- a first voltage according to the DAC code;
- and
- a second voltage according to the calibration code;
- a differential operational amplifier (DOA) connected to the DAC and configured to:
- receive the first voltage;
- receive a feedback voltage;
- and
- generate an op-amp output voltage;
- a driver connected to the output terminal of the DOA, wherein the driver responds to the op-amp output voltage by generating a drive current;
- a feedback circuit connected to the DAC, the driver, and the DOA, and configured to generate the feedback voltage according to the second voltage;
- and
- a replica circuit connected to:
- the current comparator circuit;
- the output terminal of the DOA;
- and
- the driver;
- wherein the replica circuit generates a replica current that is proportional to the drive current.
20 more elements
A method for calibrating a driver, comprising:
- generating a threshold current;
- generating a replica current that is proportional to a drive current of the driver;
- comparing the replica current to the threshold current;
- generating a comparator output voltage according to the comparison;
- transmitting the comparator output voltage to a controller;
- generating a calibration code according to the comparator output voltage;
- generating a first voltage according to the calibration code;
- and
- applying the first voltage to an operational amplifier.
6 more elements
An imaging system, comprising:
- a generator circuit configured to generate a bias voltage;
- a current comparator circuit connected to the generator circuit and configured to generate a threshold current;
- a controller configured to:
- store a plurality of calibration codes;
- and
- transmit one calibration code of the plurality of calibration codes;
- a digital-to-analog converter (DAC) connected to the generator circuit and configured to:
- receive the calibration code;
- generate a DAC voltage;
- and
- generate a calibration voltage according to the calibration code;
- a differential operational amplifier (DOA) connected to the DAC and comprising:
- a first input terminal and a second input terminal, wherein the DOA is configured to:
- receive the DAC voltage at the first input terminal;
- receive a feedback voltage at the second input terminal;
- and
- generate an op-amp output voltage at an output terminal;
- a driver connected to the output terminal of the DOA and comprising a drive transistor;
- wherein:
- a gate terminal of the drive transistor is connected to the output terminal of the DOA;
- and
- a source terminal of the drive transistor is connected to the second input terminal of the DOA;
- a feedback circuit connected to the DAC, the driver, and the DOA, and configured to generate the feedback voltage according to the calibration voltage;
- and
- a replica circuit comprising a replica transistor, wherein:
- a gate terminal of the replica transistor is connected to the output terminal of the DOA;
- a drain terminal is of the replica transistor is connected to the current comparator circuit;
- and
- a source terminal of the replica circuit is connected to a source terminal of the drive transistor.
26 more elements
Dependencies are inferred from the claim text.