Pixel ADC Comparator Circuit for Faster Imaging Signal Determination
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Solution Overview
Problem
In solid-state imaging apparatuses, the limited area for housing circuits within each pixel makes it difficult to manufacture comparators that meet requirements, often leading to reduced determination speed.
Innovation Solution
A solid-state imaging apparatus with an A/D converter that includes a differential input circuit, a positive feedback circuit operating on a lower power supply voltage to accelerate comparison result signal transitions, a voltage conversion circuit, and a data storage section to store time codes, along with multiple time code transfer sections using shift registers to enhance determination speed.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If the area for housing circuits is limited within each pixel, then area efficiency is improved, but comparator determination speed deteriorates
Solution Approach 1:
The comparator is divided into two separate circuits: a differential input circuit operating at high voltage for accurate comparison, and a positive feedback circuit operating at low voltage for rapid signal transition. This segmentation allows each circuit to be optimized independently, resolving the contradiction between area constraints and speed requirements.
Solution Approach 2:
The patent dynamically switches between two operating modes: the differential input circuit performs voltage comparison at high voltage levels, then the positive feedback circuit rapidly transitions the output signal at low voltage levels. This dynamic operation enables both accurate comparison and fast determination within limited area.
2Measurement precision
If high voltage is used in the comparator, then determination accuracy is improved, but power consumption increases
Solution Approach 1:
The comparator functionality is segmented into two voltage domains: the differential input circuit operates at high voltage (first power supply voltage) to ensure accurate voltage comparison, while the positive feedback circuit operates at low voltage (second power supply voltage) to reduce power consumption during signal transition.
Solution Approach 2:
Different parts of the comparator operate at different voltage levels according to their functional requirements: the input comparison stage uses high voltage for precision, while the output transition stage uses low voltage for energy efficiency. This local quality differentiation resolves the power-accuracy trade-off.
Data Source
AI summary
The present disclosure relates to a solid-state imaging apparatus, a method for driving the solid-state imaging apparatus, and electronic equipment for improving the determination speed of comparators and allowing the comparators to operate faster. A differential input circuit operates on a first power supply voltage and outputs a signal when a voltage of a pixel signal is higher than a voltage of a reference signal. A voltage conversion circuit converts the output signal from the differential input circuit into a signal corresponding to a second power supply voltage. A positive feedback circuit accelerates a transition rate at which a comparison result signal of a comparison in voltage between the pixel signal and the reference signal is inverted. Multiple time code transfer sections each include a shift register that transfer a time code. The present disclosure can be applied, for example, to an imaging apparatus including A/D converters disposed in pixels.