Apparatus for providing correlated double sampling of analog video data from an image pixel array
Disclosed herein is a camera system and camera controller having a modularized design. Camera control functions within the controller are distributed among a number of modules, each module performing a component task of controlling a camera. Individual modules can perform tasks such as generating clock signals, digitizing an analog video signal, and providing multiplexed digital video output. Modules communicate with each other over a common bus sufficient to carry the signals necessary to control the camera. The system implements a RAM-based digital sequencer that provides the capability of loading bit patterns into memory and using these patterns to generate waveforms for clocking a CCD. Clock and readout sequences can be composed in a high level language, compiled and uploaded into the controller. Adjustable clamp and sample signal delays used in digitizing an analog video signal provide the capability to optimize the performance of the system in a given application.
1. An apparatus for performing correlated double sampling of analog video data from an image pixel array comprising:
an offset voltage circuit configured to receive a digital input data indicative of an analog voltage and further configured to output an offset voltage corresponding to said digital input data;
a clamp delay circuit configured to receive a clamp signal and clamp delay setting data, and further configured to output a delayed clamp signal, delayed in time by an amount indicated by the clamp delay setting data;
an analog-to-digital converter receiving an analog video input signal from a camera head, configured to convert the analog video input signal to a digital video output signal upon receipt of a sample signal; and
a clamp circuit electrically connected to the clamp delay circuit, the offset voltage circuit, and the analog video input signal, configured to electrically connect the analog offset voltage and the analog video input signal upon receipt of the delayed clamp signal.
2. The apparatus of claim 1 wherein the clamp delay setting data can be adjusted in one quarter (0.25) nanosecond increments.
3. The apparatus of claim 1 further comprising:
a sample delay circuit configured to receive a sample signal and a sample delay setting data, and further configured to output a delayed sample signal delayed in time by an amount indicated by the sample delay setting data.
4. The apparatus of claim 3 wherein the sample delay setting can be adjusted in one quarter (0.25) nanosecond increments.