L-C low pass filter correlator

• US 6,055,016 A
• Filed: 12/23/1994
• Issued: 04/25/2000
• Est. Priority Date: 12/23/1994
• Status: Expired due to Fees

• Current Assignee: Redlake MASD LLC (Roper Technologies, Inc.)
• Original Assignee: Eastman Kodak Company
• Inventors: Flogstad, Hokon Olav, Darden, Kim M
• Primary Examiner(s): Ho, Tuan
• Assistant Examiner(s): Vu, Ngoc-Yen, VU, NGOC YEN T
• Application Number:
  US08/363,133
• Time in Patent Office: 1,950 Days
• Field of Search: 348/241, 348/533, 348/534, 348/607, 348/683, 348/250, 348/222, 348/312
• US Class Current: 348/250
• CPC Class Codes: H04N 25/616 involving a correlated sampling function, e.g. correlated double sampling [CDS] or triple sampling
• CPC Class Codes: H04N 25/71 Charge-coupled device [CCD] sensors; Charge-transfer registers specially adapted for CCD sensors
• CPC Class Codes: H04N 25/75 Circuitry for providing, modifying or processing image signals from the pixel array

Abstract

An L-C low pass filter correlator circuit for removing noise from an image signal produced by a solid state imaging device such as a CCD sensor.

Claims

1. A correlator circuit for removing noise from a signal, comprising:

an input section for receiving an analog signal having a period including a first interval with a first signal value and a second interval with a second signal value, said input section including a series capacitor and parallel input resistor;

a passive, double correlating low filter section coupled to said input section and including at least one series inductor, parallel capacitor (L-C) low pass filter section; and

an output section coupled to said low pass filter section for outputting an output analog signal across an output resistor, said output signal being free from noise and having a signal value which is a function of the difference between said first signal value and said second signal value.

2. The correlator circuit of claim 1 including a analog-to-digital converter coupled to said output section for converting said output signal into a digital signal.

3. The correlator circuit of claim 1 wherein said input resistor and said output resistor have substantially equal resistance values.

4. The correlator circuit of claim 1 wherein said low pass filter section includes a plurality of cascaded L-C low pass filter sections.

5. The correlator circuit of claim 1 wherein said low pass filter section is configured as a Bessel filter.

6. The correlator circuit of claim 1 wherein said input section receives an image signal having a pixel period including a first interval with a reset signal value and a second interval with an image signal value;

and wherein said output section outputs an image signal which is a function of the difference between said reset signal value and said image signal value.

7. The correlator circuit of claim 6 including an image signal source coupled to said input section for providing said image signal.

8. The correlator circuit of claim 7 wherein said image signal source is a solid state sensor.

9. The correlator circuit of claim 8 wherein said solid state sensor is a CCD sensor.