Readout circuit with charge dump circuit
AssigneeTexas Instruments Incorporated
InventorsSravana Kumar Goli, Nagesh Surendranath, Saugata Datta, Sandeep Oswal
Life of this patent
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Abstract
A circuit includes an amplifier having an input and an output. A voltage comparator has an input and first and second outputs. The input of the voltage comparator is coupled to the output of the amplifier. A variable capacitor circuit is coupled between the input and the output of the amplifier and is coupled to the first output of the voltage comparator. A charge dump circuit has an input and an output. The input of the charge dump circuit is coupled to the second output of the voltage comparator. The output of the charge dump circuit is coupled to the input of the amplifier.
Claims20
A circuit comprising:
- an amplifier having an input and an output;
- a voltage comparator having an input and first and second outputs, the input of the voltage comparator coupled to the output of the amplifier;
- a variable capacitor circuit coupled between the input and the output of the amplifier, and coupled to the first output of the voltage comparator;
- and
- a charge dump circuit having an input and an output, the input of the charge dump circuit coupled to the second output of the voltage comparator, the output of the charge dump circuit coupled to the input of the amplifier.
An electronic system, comprising:
- an imaging device configured to provide a signal;
- a back-end readout circuit configured to generate a digital signal from an output voltage;
- and
- a circuit coupled between the imaging device and the back-end readout circuit, wherein the circuit is configured to generate the output voltage based on the signal from the imaging device, the circuit comprising:
- an amplifier having an input and an output;
- a voltage comparator having a first input, a first output, and a second output, the first input of the voltage comparator coupled to the output of the amplifier;
- a variable capacitor circuit coupled between the input and the output of the amplifier and coupled to the first output of the voltage comparator, and comprising a first capacitor and a second capacitor coupled in parallel with one another between the input and the output of the amplifier;
- and
- a charge dump circuit having an input and an output, the input of the charge dump circuit coupled to the second output of the voltage comparator, the output of the charge dump circuit coupled to the input of the amplifier.
A method, comprising:
- receiving an input signal at an amplifier, the input signal having an input charge level;
- providing an output voltage from the amplifier based on the input signal;
- detecting whether a first voltage drop has occurred by determining whether the output voltage drops below a first threshold voltage;
- detecting whether a second voltage drop has occurred by determining whether the output voltage drops below a second threshold voltage after the first voltage drop has occurred, wherein the first threshold voltage is less than the second threshold voltage;
- and
- changing the input charge level of the input signal by a charge value based on whether the second voltage drop has occurred.
Dependencies are inferred from the claim text.