High-sensitivity storage pixel sensor having auto-exposure detection
First Claim
1. A plurality of storage pixel sensors disposed on a semiconductor substrate, each of the plurality of storage pixel sensors comprising:
- a photodiode having a first terminal coupled to a first potential and a second terminal;
a reset transistor having a first terminal coupled to the second terminal of the photodiode, a second terminal coupled to a reset reference potential that reverse biases the photodiode, and a control gate coupled to a RESET signal node;
a photocharge integration node coupled to said first terminal of said reset transistor, said photocharge integration node comprising the control gate of a source-follower transistor, said source-follower transistor having a drain, coupled to a source-follower drain supply voltage node, and a source coupled to means for generating a bias current;
a capacitive storage node, coupled to the source of the source-follower transistor, comprising the input of a readout amplifier transistor having an output; and
an exposure transistor having a source directly connected to the source of said source-follower transistor and a drain coupled to a global current-summing node, said exposure transistor having a control gate coupled to a saturation level control voltage, said exposure transistor and said source-follower transistor acting as a common-source differential pair to divide said bias current between said source-follower transistor and said exposure transistor according to the relative values of integrated photosignal on said control gate of said source-follower transistor and said saturation level control voltage on said gate of said exposure transistor.
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Abstract
A storage pixel sensor disposed on a semiconductor substrate comprises a photodiode having a first terminal coupled to a first potential and a second terminal. A barrier transistor has a first terminal coupled to the second terminal of the photodiode, a second terminal and a control gate coupled to a barrier set voltage. A reset transistor has a first terminal coupled to the second terminal of the barrier transistor, a second terminal coupled to a reset reference potential that reverse biases the photodiode, and a control gate coupled to a source of a RESET signal. A photocharge integration node is coupled to said second terminal of said barrier transistor. The photocharge integration node comprises the control gate of a first source-follower transistor. The first source-follower transistor is coupled to a source of bias current and has an output. A capacitive storage node is coupled to the output of the first source-follower transistor and comprises the control gate of a second source-follower transistor having an output. An exposure transistor is coupled between the output of the first source-follower transistor and a global current-summing node and has a control gate coupled to a saturation level voltage.
105 Citations
30 Claims
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1. A plurality of storage pixel sensors disposed on a semiconductor substrate, each of the plurality of storage pixel sensors comprising:
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a photodiode having a first terminal coupled to a first potential and a second terminal;
a reset transistor having a first terminal coupled to the second terminal of the photodiode, a second terminal coupled to a reset reference potential that reverse biases the photodiode, and a control gate coupled to a RESET signal node;
a photocharge integration node coupled to said first terminal of said reset transistor, said photocharge integration node comprising the control gate of a source-follower transistor, said source-follower transistor having a drain, coupled to a source-follower drain supply voltage node, and a source coupled to means for generating a bias current;
a capacitive storage node, coupled to the source of the source-follower transistor, comprising the input of a readout amplifier transistor having an output; and
an exposure transistor having a source directly connected to the source of said source-follower transistor and a drain coupled to a global current-summing node, said exposure transistor having a control gate coupled to a saturation level control voltage, said exposure transistor and said source-follower transistor acting as a common-source differential pair to divide said bias current between said source-follower transistor and said exposure transistor according to the relative values of integrated photosignal on said control gate of said source-follower transistor and said saturation level control voltage on said gate of said exposure transistor. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. A plurality of storage pixel sensors disposed on a semiconductor substrate, each of the plurality of storage pixel sensors comprising:
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a photodiode having a first terminal coupled to a first potential and a second terminal;
a barrier transistor having a first terminal coupled to the second terminal of the photodiode, said barrier transistor having a second terminal and a control gate coupled to a barrier set voltage;
a reset transistor having a first terminal coupled to the second terminal of the barrier transistor, a second terminal coupled to a reset reference potential that reverse biases the photodiode, and a control gate coupled to a RESET signal node;
a photocharge integration node coupled to said second terminal of said barrier transistor, said photocharge integration node comprising the control gate of a source-follower transistor, said source-follower transistor having a drain, coupled to a source-follower drain supply voltage node, and a source;
a capacitive storage node, coupled to said source of said source-follower transistor, comprising the input of a readout amplifier transistor having an output; and
an exposure transistor having a source directly connected to the source of said source-follower transistor and a drain coupled to a global current-summing node, said exposure transistor having a control gate coupled to a saturation level control voltage, said exposure transistor and said source-follower transistor acting as a common-source differential pair to divide said bias current between said source-follower transistor and said exposure transistor according to the relative values of integrated photosignal on said control gate of said source-follower transistor and said saturation level control voltage on said gate of said exposure transistor. - View Dependent Claims (12, 13, 14, 15, 16, 17, 18, 19)
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20. A pixel sensor disposed on a semiconductor substrate comprising:
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a photodiode having a first terminal coupled to a first potential and a second terminal;
a reset transistor having a first terminal coupled to the second terminal of the photodiode, a second terminal coupled to a reset reference potential that reverse biases the photodiode, and a control gate coupled to a RESET signal node;
a photocharge integration node coupled to said first terminal of said reset transistor, said photocharge integration node comprising the control gate of a source-follower transistor, said source-follower transistor having a drain coupled to a source-follower drain supply voltage node and a source coupled to means for generating a bias current; and
an exposure transistor having a source directly connected to said output of said source-follower transistor and drain directly connected to a global current-summing node, said exposure transistor having a control gate coupled to a saturation level control voltage, said exposure transistor and said source-follower transistor acting as a common-source differential pair to divide said bias current between said source-follower transistor and said exposure transistor according to the relative values of integrated photosignal on said control gate of said source-follower transistor and said saturation level control voltage on said gate of said exposure transistor. - View Dependent Claims (21, 22, 23, 24, 25, 26, 27, 28, 29, 30)
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Specification