Noise-Reducing Solid-State Imaging Design for Low Power
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Summary
Problems
In CMOS image sensors, noise components from reference signal fluctuations can affect adjacent pixel columns during analog-to-digital conversion, leading to image streaks, and reducing power consumption while minimizing noise impact is challenging, especially in low-power modes like live view.
Innovation solutions
A solid-state imaging element with a source follower circuit architecture, where each pixel column has a dedicated input circuit with a first transistor and switch connected to a common reference signal input and output wiring, allowing selective operation of input circuits to reduce noise propagation and power consumption.
TRIZ Analysis
Specific contradictions:
General conflict description:
Principle concept:
If a source follower circuit is provided in the reference signal input unit of each AD conversion unit to prevent noise propagation, then noise suppression is improved, but power consumption cannot be reduced when thinning out the number of output columns
Why choose this principle:
Multiple input circuits share a common reference signal input wiring and common output wiring, merging the reference signal distribution path while maintaining individual column isolation through the switch mechanism
Principle concept:
If a source follower circuit is provided in the reference signal input unit of each AD conversion unit to prevent noise propagation, then noise suppression is improved, but power consumption cannot be reduced when thinning out the number of output columns
Why choose this principle:
The first switch in each input circuit dynamically changes state between on and off based on whether the corresponding column is selected for output, allowing the circuit to adapt between full operation and thinned operation modes
Application Domain
Data Source
AI summary:
A solid-state imaging element with a source follower circuit architecture, where each pixel column has a dedicated input circuit with a first transistor and switch connected to a common reference signal input and output wiring, allowing selective operation of input circuits to reduce noise propagation and power consumption.
Abstract
Provided is a solid-state imaging element capable of thinning out the number of operations of AD conversion units while suppressing an influence of a noise component on the AD conversion units of other columns. A solid-state imaging element according to the present embodiment includes: a plurality of comparators that is provided corresponding to a plurality of pixel columns each including an array of a plurality of pixels that photoelectrically converts light and outputs a pixel signal, and compares the pixel signal with a reference signal; a reference signal generation unit that generates a common reference signal used to generate the reference signal, and a plurality of input circuits respectively corresponding to the plurality of pixel columns and provided between the plurality of comparators and the reference signal generation unit; a common input wiring through which the common reference signal is input to the plurality of input circuits; and a common output wiring that outputs the reference signal from the plurality of input circuits to the plurality of comparators, in which each of the plurality of input circuits includes: a first transistor having a gate connected to the common input wiring; and a first switch connected between a source of the first transistor and the common output wiring.