Digital pixel imager with dual bloom storage capacitors and cascode transistors
First Claim
1. An integration capacitor network for connection to a photo-current source, the network comprising:
- an input;
a first path connected between the input and a reset voltage, the first path including a first integration capacitor and a first cascode transistor, the first cascode transistor coupled between the input and the first integration capacitor; and
a second path connected between the input and the reset voltage, the second path including a second integration capacitor and a second cascode transistor, the second cascode transistor coupled between the input and the second integration capacitor;
wherein gates of the first and second cascode transistors are connected to a reference voltage; and
wherein charge is accumulated on the first integration capacitor until a voltage on the first integration capacitor exceeds the reference voltage and then charge is accumulated on the second integration capacitor.
1 Assignment
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Accused Products
Abstract
An integration capacitor network for connection to a photo-current source includes: an input; a first path connected between the input and a reset voltage, the first path including a first integration capacitor and a first cascode transistor, the first cascode transistor coupled between the input and the first integration capacitor; and a second path connected between the input and the reset voltage, the second path including a second integration capacitor and a second cascode transistor, the second cascode transistor coupled between the input and the second integration capacitor. Gates of the first and second cascode transistors are connected to a reference voltage and charge is accumulated on the first integration capacitor until a voltage on the first integration capacitor exceeds the reference voltage and then charge is accumulated on the second integration capacitor.
5 Citations
20 Claims
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1. An integration capacitor network for connection to a photo-current source, the network comprising:
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an input; a first path connected between the input and a reset voltage, the first path including a first integration capacitor and a first cascode transistor, the first cascode transistor coupled between the input and the first integration capacitor; and a second path connected between the input and the reset voltage, the second path including a second integration capacitor and a second cascode transistor, the second cascode transistor coupled between the input and the second integration capacitor; wherein gates of the first and second cascode transistors are connected to a reference voltage; and wherein charge is accumulated on the first integration capacitor until a voltage on the first integration capacitor exceeds the reference voltage and then charge is accumulated on the second integration capacitor. - View Dependent Claims (2, 3, 4, 5, 6, 7, 16)
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8. A digital pixel comprising:
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a photo-current source; a comparator; a counter coupled to an output of the comparator; a controller coupled to the output of the comparator; and an integration capacitor network comprising; an input; a first path connected between the input and a reset voltage, the first path including a first integration capacitor and a first cascode transistor, the first cascode transistor coupled between the input and the first integration capacitor; a second path connected between the input and the reset voltage, the second path including a second integration capacitor and a second cascode transistor, the second cascode transistor coupled between the input and the second integration capacitor; and an output connected to the comparator; wherein gates of the first and second cascode transistors are connected to a reference voltage; and wherein the controller is configured to cause the integration capacitor network to accumulate charge on the first integration capacitor until a voltage on the first integration capacitor exceeds the reset voltage and then charge is accumulated on the second integration capacitor. - View Dependent Claims (9, 10, 11, 12, 13, 14, 15)
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17. A method of operating a digital pixel, the method comprising:
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storing charge from a photo-current source in a first integration capacitor until a voltage across the first integration capacitor exceeds a reference voltage; storing charge from the photo-current source in a second integration capacitor after the voltage in the first integration capacitor exceeds the reference voltage; and while storing charge in the second integration capacitor, subtracting voltage from the first integration capacitor. - View Dependent Claims (18, 19, 20)
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Specification