METHOD AND APPARATUS FOR BACKSIDE ILLUMINATED IMAGE SENSORS USING CAPACITIVELY COUPLED READOUT INTEGRATED CIRCUITS
First Claim
1. A back-side illuminated image sensor having two circuits capacitively coupled to each other at the pixel level, comprising:
- a capacitor having a first plate and a second plate;
a first circuit comprising;
a photon detector for receiving a plurality of photons and providing a charge signal corresponding to the received photons,an integrator, connected to the photon detector, for determining a cumulative signal based on the charge signal for a given exposure time and producing an integrator output signal based on the cumulative signal, anda comparator, connected to the integrator and the first plate of the capacitor, for producing a comparator output signal that is sent to the first plate of the capacitor when the integrator output signal has reached a threshold level; and
a second circuit comprising;
a receiver, connected to the second plate of the capacitor, for detecting a plurality of pulses from capacitively coupled signals received from the first circuit, anda counter, connected to the receiver, for counting the plurality of pulses detected by the receiver;
wherein the first circuit and the second circuit are capacitively coupled to one another via the capacitor.
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Accused Products
Abstract
The images sensor includes a readout circuit capacitatively coupled to a memory circuit. The readout circuit includes: (i) a photon detector to receive a plurality of photons and to provide a charge signal corresponding to the received photons, (ii) a resettable integrator that is reset multiple times over a single exposure time and provides an analog representation of the incident photons during the last integration cycle, and (iii) a comparator that monitors the integrator output and generates a reset pulse when the integrator reaches a built-in threshold value. The memory circuit includes: (i) a receiver circuit that detects the output of the digital driver in the front-end readout circuit via capacitive coupling and generates a digital voltage pulse for each received signal, and (ii) a digital counting memory to count the received pulses to provide a coarse digital representation of how many times the integrator is reset.
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Citations
20 Claims
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1. A back-side illuminated image sensor having two circuits capacitively coupled to each other at the pixel level, comprising:
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a capacitor having a first plate and a second plate; a first circuit comprising; a photon detector for receiving a plurality of photons and providing a charge signal corresponding to the received photons, an integrator, connected to the photon detector, for determining a cumulative signal based on the charge signal for a given exposure time and producing an integrator output signal based on the cumulative signal, and a comparator, connected to the integrator and the first plate of the capacitor, for producing a comparator output signal that is sent to the first plate of the capacitor when the integrator output signal has reached a threshold level; and
a second circuit comprising;a receiver, connected to the second plate of the capacitor, for detecting a plurality of pulses from capacitively coupled signals received from the first circuit, and a counter, connected to the receiver, for counting the plurality of pulses detected by the receiver; wherein the first circuit and the second circuit are capacitively coupled to one another via the capacitor. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13)
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14. A back-side illuminated image sensor having two circuits capacitively coupled to each other at the pixel level, comprising:
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a coupling capacitor having a first plate and a second plate; a first circuit comprising; an integrator for determining a cumulative signal based on a charge signal for a given exposure time and producing an integrator output signal based on the cumulative signal, and a comparator, connected to the integrator and the first plate of the capacitor, for producing a comparator output signal that is sent to the first plate of the coupling capacitor when the integrator output signal has reached a threshold level; and a second circuit comprising a receiver, connected to the second plate of the coupling capacitor, for detecting a plurality of pulses from capacitively coupled signals received from the first circuit, wherein the first circuit and the second circuit are capacitively coupled to one another via the coupling capacitor. - View Dependent Claims (15, 16, 17, 18, 19, 20)
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Specification