Image Sensor ADC Preamplifier Bypass for Lower Power Conversion
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Solution Overview
Problem
In solid-state imaging devices, the use of dynamic comparators in sequential-conversion-type A/D conversion circuits leads to high power consumption due to the requirement for a preamplifier with high linearity and noise characteristics, which is not efficiently managed, especially when a large number of A/D conversion circuits are operated simultaneously.
Innovation Solution
A solid-state imaging device configuration where a preamplifier is shut down, and switching elements connect the input terminals of the preamplifier directly to the comparator section, allowing the comparator to operate without the preamplifier, thereby reducing power consumption by bypassing the preamplifier section.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a preamplifier with high linearity and excellent noise characteristics is provided preceding the dynamic comparator, then the resolution is improved, but the power consumption increases
Solution Approach 1:
The preamplifier's operation mode is made dynamic by switching between normal operation and shutdown states based on signal conditions. The control signal dynamically adjusts the preamplifier's gain and power consumption levels, allowing the system to adapt between high precision mode (when signal differentiation is needed) and low power mode (when signals are clearly distinguishable), thus resolving the contradiction between resolution and power consumption.
Solution Approach 2:
The invention changes the operational parameters of the preamplifier by controlling its shutdown state through a control signal. By adjusting parameters such as gain, bandwidth, and power supply voltage based on signal characteristics, the preamplifier can operate at full performance when needed and at reduced power consumption when the dynamic comparator can function adequately without full preamplification.
2Productivity
If a large number of A/D conversion circuits are simultaneously operated, then the productivity is improved, but the streaking increases due to common impedance
Solution Approach 1:
The invention segments the power supply and ground paths for each A/D conversion circuit into separate, isolated routes. By providing individual power supply lines and ground connections for each circuit block, the common impedance that causes streaking is eliminated while allowing all circuits to operate simultaneously at full productivity.
3Use of energy by moving object
If the preamplifier is shut down to reduce power consumption, then the power consumption is reduced, but the linearity and noise characteristics are degraded
Solution Approach 1:
The preamplifier transitions dynamically between full operation and shutdown states based on real-time signal analysis. When the dynamic comparator can adequately handle the input signals, the preamplifier enters shutdown mode to reduce power consumption. When signal precision is critical, the preamplifier activates to provide full linearity and noise performance, thus balancing power consumption with measurement precision.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This configuration reduces power consumption by moderating the linearity and noise characteristics of the preamplifier and allows for a higher intermittence rate, especially during low pixel count operations, thereby decreasing the number of A/D conversions and overall power usage.
Implementation Method 1
a pixel array section in which a plurality of pixels is disposed in an array, the plurality of pixels performing photoelectric conversion and outputting respective pixel signals
Data Source
AI summary
Solid-state imaging devices and electronic equipment are disclosed. In one example, a solid-state imaging device includes a pixel array section with pixels that perform photoelectric conversion disposed in an array. A preamplifier section receives pixel signals from the pixels and a threshold signal, and amplifies their differences as differential signals. The preamplifier section is set to a shutdown state on the basis of a first control signal input. A comparator compares the differential signals with a comparison reference signal. A preamplifier through circuit includes switching elements connecting the input terminals of the preamplifier section to input terminals of the comparator section, and sets the switching elements to a connection state on the basis of a second control signal input in the shutdown state. Thus, power consumption can be reduced under conditions that allow characteristics required for the preamplifier section to be moderated.