L-TSPC Counter Architecture for Two-Phase Pixel Conversion
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional CMOS image sensor architectures face challenges in achieving high-speed, high-resolution pixel conversions while maintaining low power consumption and efficient noise reduction, particularly due to limitations in counter clock speeds and resource utilization in multi-phase conversion processes.
Innovation Solution
The implementation of a loadable true-single-phase-clocking (L-TSPC) flop-based counter architecture that integrates counting, subtraction, and read-out operations, utilizing an N-bit counter block with L-TSPC flops and data flip-flops to support high-speed and efficient multi-phase pixel conversions by pre-subtracting initial counts and reloading values to maintain deterministic states during clocking cessation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If conventional counter architectures are used in CMOS image sensors, then the system can perform basic pixel conversion, but the counter clock speed is limited and power consumption increases
Solution Approach 1:
The patent implements dynamic clock gating that selectively enables or disables counter stages based on the current conversion phase and data validity. During phases where certain counter stages are not needed for noise reduction or baseline subtraction, their clocks are gated off, reducing dynamic power consumption while maintaining the ability to operate at high clock speeds when full performance is required
Solution Approach 2:
The patent performs preliminary baseline subtraction and noise characterization in dedicated phases before final pixel conversion. By pre-processing these operations and storing results in separate registers, the counter can operate at reduced speeds or with fewer active stages during the actual pixel conversion phase, reducing overall power consumption while maintaining high-speed capability when needed
2Measurement precision
If multi-phase pixel conversion is implemented for noise reduction, then measurement precision improves, but device complexity increases
Solution Approach 1:
The patent segments the pixel conversion process into distinct phases (baseline phase, noise characterization phase, and signal conversion phase), each handled by dedicated counter instances or counter stages. This segmentation allows each phase to be optimized independently and enables parallel processing of multiple phases, improving measurement precision through noise reduction while managing complexity through modular architecture
Solution Approach 2:
The patent designs the counter architecture to perform multiple functions: it can count during baseline acquisition, during noise characterization, and during signal conversion. The same counter blocks can be reconfigured or reused across different phases with appropriate control logic, reducing overall device complexity compared to having separate dedicated counters for each phase
3Productivity
If high-speed clocking is used for pixel conversion, then productivity improves, but manufacturing precision becomes more difficult to maintain
Solution Approach 1:
The patent introduces specialized control logic and synchronization circuits that act as intermediaries between the high-speed clock and the counter stages. These intermediaries ensure proper timing alignment, phase synchronization, and signal coordination even at high clock speeds, maintaining manufacturing precision through robust timing control mechanisms
Solution Approach 2:
The patent replaces traditional mechanical or purely sequential counter architectures with a digitally-controlled system that uses synchronous logic and pipeline registers. This substitution allows high-speed operation while maintaining precision through digital timing control, eliminating the timing drift and synchronization issues associated with mechanical or asynchronous systems
4Speed
If L-TSPC flops are used in the counter, then counter clock speed increases, but the flops require deterministic states that complicate the architecture
Solution Approach 1:
The patent implements self-reset or self-synchronization logic within the L-TSPC flop structure that automatically restores deterministic states without external intervention. The flops are designed to self-correct or self-initialize at the beginning of each conversion phase, eliminating the need for complex external state management circuitry while maintaining the high-speed benefits of L-TSPC operation
Solution Approach 2:
The patent applies periodic reset or synchronization signals to the L-TSPC flops at the beginning of each conversion phase or at regular intervals. This periodic action ensures that the flops maintain deterministic states required for high-speed operation, while the regular timing of these reset signals simplifies the control logic compared to continuous or event-driven state management
Data Source
AI summary
Techniques are described for implementing counter architectures to support high-speed, high-resolution pixel conversions, such as for CMOS image sensor applications. Embodiments implement a counter block that uses loadable true-signal-phase-clocking (L-TSPC) flops for at least a portion of the counter flops. Some embodiments support efficient two-phase pixel conversion by integrating counting, subtraction, and shifting out in the counter. For example, embodiments can perform a first high-speed pixel conversion phase to obtain a first conversion count. Prior to a second phase, the initial counter can be pre-subtracted by the amount of the first conversion count. Embodiments can then perform a second high-speed pixel conversion phase to obtain a second conversion count. As the second conversion count already has the first conversion count pre-subtracted, the second conversion count represents the final two-phase conversion result. Embodiments can read out this final two-phase conversion result as a digital output of the counter.