Multi-Gain Ramp ADC Handover for Faster High-Resolution Conversion
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current analog-to-digital converters (ADCs) in image sensors face challenges with increased conversion time and power consumption as bit resolution increases, particularly due to the ramp ADC topology, which becomes slow and power-inefficient.
Innovation Solution
The proposed solution involves an analog-to-digital converter with an amplifying stage generating multiple amplified analog signals of different gains, a comparison stage comparing these signals with a ramp signal, and a control stage that determines when to switch between comparison outputs based on handover points to control the counter stage, allowing for efficient conversion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the number of bits of resolution is increased, then the measurement precision is improved, but the conversion time increases and power consumption increases
Solution Approach 1:
The analog signal is divided into multiple segments by generating N amplified analog signals with different gains. Each segment corresponds to a different gain level, allowing the converter to process different signal ranges in parallel rather than sequentially, thus reducing conversion time while maintaining high bit resolution
Solution Approach 2:
The invention adds a gain dimension to the conversion process by creating multiple amplified signal paths with different gains. This dimensional expansion allows simultaneous comparison of the same analog signal across multiple gain levels, enabling faster conversion without sacrificing precision
2Measurement precision
If the number of bits of resolution is increased, then the measurement precision is improved, but the power consumption increases
Solution Approach 1:
The conversion process is segmented into parallel comparison operations for different gain levels. By dividing the signal processing into discrete gain segments that can be evaluated simultaneously, the total power consumption is distributed across parallel low-power operations rather than requiring high power for sequential processing
Solution Approach 2:
The control stage dynamically selects which comparison output to use based on handover points, enabling adaptive power management. The system can switch between different gain paths depending on signal characteristics, optimizing power consumption while maintaining precision
3Measurement precision
If the steepness of the ramp is reduced, then the quantisation error is reduced, but the input range is reduced
Solution Approach 1:
The input range is segmented into multiple zones, each handled by a different gain level. By dividing the overall input range into segments that can be processed with different ramp steepness values, the system achieves fine quantisation in each segment while covering a wide total range
Solution Approach 2:
Different gain levels provide locally optimized conversion characteristics for different input ranges. Each gain path is tailored with appropriate steepness for its specific range, achieving low quantisation error locally while the combination of all paths provides wide overall input range coverage
4Speed
If multiple amplified analog signals with different gains are generated and compared, then the conversion speed is increased, but the device complexity is increased
Solution Approach 1:
The comparison stage is designed with universal functionality to handle multiple gain signals simultaneously. By creating a multi-functional comparison architecture that can process N different gain paths through a unified control mechanism, the system achieves high conversion speed without proportionally increasing complexity
Solution Approach 2:
Multiple comparison operations are merged into a unified control structure where the control stage integrates outputs from all gain paths. This combining approach allows parallel processing for speed while consolidating control logic to manage complexity
Data Source
AI summary
An analog-to-digital converter (110) comprises an analog signal input (122) for receiving an analog signal and an amplifying stage (160) configured to generate a set of N amplified analog signals, where N is an integer ≥2. The set of N signals have different gains. The ADC has a ramp signal input (121) for receiving a ramp signal and a clock input (143) for receiving at least one clock signal. A comparison stage (120) is connected to the set of amplified analog signals (SigG1, SigG2) and to the ramp signal input (121). The comparison stage (120) is configured to compare the amplified analog signals with the ramp signal to provide comparison outputs during a conversion period. A control stage is configured to control the counter stage (140) based on the comparison outputs and a selection input indicative of when at least one handover point has been reached during the conversion period.