Low noise charge gain hybrid imager
AssigneeXerox Corporation
InventorRaj B. Apte
Life of this patent
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Abstract
In one aspect of the present application, provided is a charge gain imaging system and a method of operating the charge gain imaging system. The method includes collecting a pixel charge. The collected pixel charge being stored by a pixel capacitance (Cp). Thereafter the pixel having the stored pixel charge is selected via a pixel select switch, and the pixel voltage is transferred and stored by data line capacitance (Cd) of a data line of the imager. An amplifier select switch is activated connecting the data line to a charge amplifier, and a charge gain defined by a relationship Cd/Cp, is sensed by a charge amplifier.
Claims19
A method of operating a charge gain hybrid imaging system comprising:
- activating an amplifier reset switch to reset a charge amplifier;
- collecting a charge of a pixel of the imaging system;
- storing the collected pixel charge in a pixel capacitor (Cp);
- selecting the pixel via a pixel select switch;
- activating a pixel reset switch to reset the pixel;
- deactivating the amplifier reset switch, wherein a gate-source capacitive charge is injected into a front end of the charge amplifier;
- transferring the pixel charge stored on the pixel capacitor (Cp) to a data line capacitor (Cd) of a data line until a full data line charge, which is associated with an effective charge gain of Cd/Cp, is reached;
- activating an amplifier select switch connecting the data line to the charge amplifier, the gate-source capacitive charge detected by a first sampling action of a sample switch, wherein the active state of the amplifier select switch encompasses the first active state of the sample switch and the charge of the data line capacitance is transferred to the charge amplifier as the charge gain defined by the relationship Cd/Cp;
- sensing the data line charge by the charge amplifier;
- deactivating the amplifier select switch after the pixel is selected, to isolate the pixel from the charge amplifier;
- and
- activating the sample switch a second time, wherein an output of the charge amplifier due to the charge gain is detected.
A low noise hybrid imaging system comprising:
- a pixel including,
- a transducer configured to generate charge in relation to a received stimulus,
- a pixel reset switch connected to a detector and to a discharge bus;
- a pixel capacitor arranged to store the transducer output as a pixel charge on the capacitor (Cp),
- a voltage amplifier connected to transfer the pixel voltage to a select switch,
- a select switch line connected to the voltage amplifier via the select switch, wherein activating the select switch transfers the pixel voltage to the data tine and a data line charge is stored in a data line capacitor (Cd),
- an amplifier select switch connected at one end to the data line, which may be used to multiplex a plurality of pixels or pixel rows;
- a charge amplifier connected to a second end of the amplifier select switch, wherein, when the amplifier select switch is turned on, a full charge from the data line capacitor is sensed by the charge amplifier, the charge provided to the charge amplifier defined as the pixel charge multiplied by the data line capacitance (Cd) divided by the pixel capacitance (Cp);
- and
- an external charge detector connected to the pixel, through use of a data line connector, the external charge detector comprised of a charge amplifier, a capacitance feedback, an amplifier reset switch, a sample and hold switch, and signal processing electronics.
A method of operating a charge gain hybrid imaging system having at least one pixel which transmits signal data to a charge amplifier, comprising:
- activating an amplifier reset switch to reset the charge amplifier;
- activating a pixel reset switch to reset the pixel;
- deactivating the amplifier reset switch, wherein a gate-source capacitive charge is injected into a front end of the charge amplifier;
- activating a sample switch a first time, wherein the gate-source capacitive charge is detected by the first sampling action, wherein an active state of an amplifier select switch encompasses the first active state of the sample switch;
- deactivating the amplifier select switch, isolating the pixel from the charge amplifier;
- activating a pixel select switch, wherein charge from a pixel capacitance of the pixel is transferred to a data line capacitance of a data line until a full data line charge is reached, and wherein the amplifier select switch remains inactive while the pixel select switch is active;
- activating the amplifier select switch, wherein the charge of the data line capacitance is transferred to the charge amplifier as a charge gain defined by the relationship Cd/Cp;
- and
- activating the sample switch a second time, wherein an output of the charge amplifier due to the charge gain is detected.
Dependencies are inferred from the claim text.