Selectable pixel amplifier for use in a photosensor array
First Claim
Patent Images
1. An amplifier suitable for processing image signals, comprising:
- an input stage having a first differential pair including two p-devices and a second differential pair, complementary to the first differential pair, including two n-devices;
a first load device for supplying current to the first differential pair and a second load device for supplying current to the second differential pair, the first load device and the second load device being biased at a common bias node;
self-biasing circuitry for generating a bias at the bias node; and
means for deselecting the amplifier in response to an external signal, the deselecting means including means for grounding the bias node and means for eliminating current in the self-biasing circuitry in response to the external signal.
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Abstract
A CMOS-based voltage signal amplifier is particularly useful for amplifying signals from a single photodiode, or a small set of photodiodes, within a large photosensitive imaging device. When the imaging device reads out image signals from a large number of photodiodes, each amplifier is selected for operation only within a very brief time window when the particular photodiode associated therewith is reading out. The amplifier of the present design is suitable for rapid power-up and power-down when it is selected and deselected.
31 Citations
9 Claims
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1. An amplifier suitable for processing image signals, comprising:
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an input stage having a first differential pair including two p-devices and a second differential pair, complementary to the first differential pair, including two n-devices;
a first load device for supplying current to the first differential pair and a second load device for supplying current to the second differential pair, the first load device and the second load device being biased at a common bias node;
self-biasing circuitry for generating a bias at the bias node; and
means for deselecting the amplifier in response to an external signal, the deselecting means including means for grounding the bias node and means for eliminating current in the self-biasing circuitry in response to the external signal. - View Dependent Claims (2, 3, 4)
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5. A photosensitive apparatus, comprising:
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a set of photosensors, each photosensor outputting a voltage signal relating to an intensity of light thereon;
a set of amplifiers, each amplifier in the set of amplifiers being associated with a photosensor in the set of photosensors, for amplifying a voltage signal from the photosensor; and
means for sending a deselection signal to any amplifier;
each amplifier including an input stage having a first differential pair including two p-devices and a second differential pair, complementary to the first differential pair, including two n-devices;
a first load device for supplying current to the first differential pair and a second load device for supplying current to the second differential pair, the first load device and the second load device being biased at a common bias node;
self-biasing circuitry for generating a bias at the bias node; and
means for deselecting the amplifier in response to the deselection signal, the deselecting means including means for grounding the bias node and means for eliminating current in the self-biasing circuitry in response to the deselection signal. - View Dependent Claims (6, 7, 8, 9)
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Specification