Complete CDS/PGA sample and hold amplifier
Patent 6529237 Issued on March 4, 2003. Estimated Expiration Date: 
November 10, 2018. Estimated Expiration Date is calculated based on simple USPTO term provisions. It does not account for terminal disclaimers, term adjustments, failure to pay maintenance fees, or other factors which might affect the term of a patent.
November 10, 2018. Estimated Expiration Date is calculated based on simple USPTO term provisions. It does not account for terminal disclaimers, term adjustments, failure to pay maintenance fees, or other factors which might affect the term of a patent.Patent ReferencesCharge amplifier for MOS imaging array and method of making same Correlated double sampling method and apparatus Sensing circuit for capturing a pixel signal Analog current mode assisted differential to single-ended read-out channel operable with an active pixel sensor Color balancing circuit and method Patent #: 6346968 InventorsAssigneeApplicationNo. 189237 filed on 11/10/1998US Classes:348/241, Including noise or undesired signal reduction348/243, Dark current348/308, Including switching transistor and photocell at each pixel site (e.g., "MOS-type" image sensor)348/533Noise reductionExaminersPrimary: Garber, Wendy R.Assistant: Ye, Lin Attorney, Agent or FirmInternational ClassesH04N 005/217H04N 009/64 H04N 005/335 H04N 005/08 AbstractA correlated double sampled/programmable gain amplifier (CDS/PGA) is disclosed which is operable to precondition a CCD output analog signal. The CDS/PGA includes an operational amplifier that is configured in a sample hold operation. The single-ended input is first clamped by a switch (34) to clamp the DC level therein for a given pixel. A switch (38) then samples the reset level onto a sampling capacitor (46), and a switch (42) thereafter samples the video signal onto one plate of a capacitor (50). The lower plates of the capacitors (46) and (50) are then equalized and the other plates thereof connected to the positive and negative inputs of the operational amplifier (68). An offset is provided by a programmable DAC (26) to account for the dark current offset. The output scale is adjusted or mapped by limiting the output between a negative and a positive reference input. The sampling capacitors (46) and (50) can be varied to vary the gain of the amplifier.Other References
Field of SearchIncluding noise or undesired signal reductionDark current In charge coupled type sensor Including switching transistor and photocell at each pixel site (e.g., "MOS-type" image sensor) Noise reduction Plural photosensitive image detecting element arrays Imaging array Photodiodes accessed by FETs Photoresistors accessed by FETs, or photodetectors separate from FET chip WITH PERIODIC SWITCHING INPUT-OUTPUT (E.G., FOR DRIFT CORRECTION) | |
