Image Sensor Global Counter Bit Masking for DDS Readout
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Solution Overview
Problem
In image sensors, the increasing number of counters for higher resolution leads to higher operation speed and power consumption, and the global counting structure with digital double sampling (DDS) increases memory capacity but not efficiently manages counting bit numbers.
Innovation Solution
A counting apparatus and image sensor that utilize a global counting unit with count masking to control the counting bit number, including a correction unit that reduces the number of reset and signal bits by using a count masking signal, and a storage unit that stores and corrects counting values using a reset digital offset value.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the number of counters is increased to achieve higher resolution in image sensors, then the measurement precision is improved, but the operation speed and power consumption deteriorate
Solution Approach 1:
The patent merges the reset counting function and signal counting function into a single global counting unit. The global counting unit performs both reset counting (for offset cancellation) and signal counting (for pixel data) by controlling the counting bit number through a count masking signal, thereby reducing the total number of counters needed while maintaining high resolution capability
Solution Approach 2:
The patent dynamically changes the counting bit number parameter by applying a count masking signal. The global counting unit adjusts the number of counting bits used for reset counting versus signal counting based on the masking signal, optimizing the balance between resolution precision and operation speed/power consumption
2Reliability
If the global counting structure with digital double sampling (DDS) is used to cancel readout offset, then the reliability is improved, but the memory capacity increases
Solution Approach 1:
The patent merges the reset counting values and signal counting values into a unified global counting structure. By using a single global counting unit with dynamic bit masking, the patent reduces the need for separate large-capacity memory structures for offset and signal data, thereby reducing overall memory capacity while maintaining DDS functionality
Solution Approach 2:
The patent applies different counting bit qualities to different parts of the counting process. The count masking signal dynamically adjusts which bits are used for reset counting versus signal counting, allowing optimized memory usage by allocating bit depth locally based on the specific counting phase rather than using maximum precision throughout
Data Source
AI summary
A counting apparatus that includes a global counting unit suitable for performing a counting operation by controlling a counting bit number based on a count masking signal; a one-shot pulse generation unit suitable for generating a storage instruction signal based on the count masking signal; a latch unit suitable for storing a counting value outputted from the global counting unit based on the storage instruction signal; and a storage unit suitable for storing the counting value loaded from the latch unit.