Pixel ADC Comparator Gating for Low-Power Imaging Sensors
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Solution Overview
Problem
Existing imaging devices face challenges in reducing power consumption, particularly in the analog-to-digital conversion process.
Innovation Solution
The imaging device incorporates a first pixel circuit with a light-receiving circuit, comparator, control circuit, and latch circuit, which generates and processes pixel signals using a ramp waveform reference signal, and an analog-to-digital conversion circuit with a comparator, control circuit, and latch circuit to efficiently convert analog signals to digital.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If an analog-to-digital conversion circuit is provided for each pixel column, then conversion accuracy is improved, but power consumption increases
Solution Approach 1:
The patent applies periodic action by controlling the comparator to operate only during specific conversion periods rather than continuously. The control circuit enables the comparator to perform analog-to-digital conversion in discrete time intervals, allowing it to remain inactive during other periods, thus reducing overall power consumption while maintaining conversion accuracy when needed
Solution Approach 2:
The patent implements dynamics by making the comparator's operation state changeable between active and inactive modes. The control circuit dynamically adjusts the comparator's operational state based on timing signals, enabling it to be turned on during conversion periods and turned off during non-conversion periods, optimizing the balance between performance and power consumption
2Speed
If the comparator operates continuously, then conversion speed is improved, but power consumption increases
Solution Approach 1:
The patent applies periodic action by controlling the comparator to operate only during specific conversion periods rather than continuously. The control circuit enables the comparator to perform analog-to-digital conversion in discrete time intervals, allowing it to remain inactive during other periods, thus reducing overall power consumption while maintaining conversion accuracy when needed
Solution Approach 2:
The patent implements preliminary action by pre-configuring the control circuit to activate the comparator at the appropriate moment before conversion is needed. The control circuit is designed to enable the comparator in advance during conversion periods, ensuring the comparator is ready to operate at high speed when required while remaining inactive during non-conversion periods to save power
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 optimizing the analog-to-digital conversion process, enhancing the efficiency and performance of the imaging device.
Implementation Method 1
pixels each including a photodiode are arranged in a matrix form, and each of the pixels generates a pixel voltage corresponding to an amount of received light
Data Source
AI summary
An imaging device of the present disclosure includes a first pixel circuit and a generation circuit. The first pixel circuit includes a first light-receiving circuit, a first comparator, a first control circuit, and a first latch circuit. The first light-receiving circuit is configured to generate a first pixel signal corresponding to the amount of received light. The first comparator is configured to generate a first comparison signal by comparing the first pixel signal with a first reference signal having a ramp waveform. The first control circuit is configured to generate a first comparison output signal by turning on and off an output of the first comparison signal on the basis of a first control signal. The first latch circuit is configured to latch a time code on the basis of transition of the first comparison output signal. The generation circuit is configured to generate the first control signal.