Comparator Circuit With Internal Voltage Drop for Auto-Zero Tuning
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Solution Overview
Problem
There is a need for a technology that can easily modify the auto-zero potential of the comparator in CMOS image sensors, as existing methods require external voltage generation circuits and additional components, making them complex and costly.
Innovation Solution
A comparator design that includes a differential pair, a current mirror, a voltage drop mechanism, and a switch, allowing for easy modification of the operating point potential by controlling the voltage drop between transistors, without the need for external voltage generation circuits.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If an externally applied voltage generation circuit is used to modify the auto-zero potential, then the operating point potential can be modified, but the device complexity increases and cost increases
Solution Approach 1:
The patent merges the voltage drop mechanism directly into the comparator circuit by connecting it between the differential pair and current mirror. This integration eliminates the need for separate external voltage generation circuits, thereby reducing device complexity while maintaining the ability to modify the operating point potential through the control signal that adjusts the voltage drop amount.
Solution Approach 2:
The comparator circuit generates and applies the necessary voltage drop internally through its own integrated components (voltage drop mechanism and switch). The control signal that adjusts the voltage drop is generated within the system, allowing the comparator to self-regulate its operating point without requiring external voltage generation circuits, thus reducing both complexity and cost.
2Adaptability or versatility
If an externally applied voltage generation circuit is used to modify the auto-zero potential, then the operating point potential can be modified, but the cost increases
Solution Approach 1:
The voltage drop mechanism is merged into the comparator circuit structure, eliminating the need for separate external voltage generation circuits. This integration reduces the total component count and simplifies the manufacturing process, thereby reducing production costs while maintaining the capability to modify the operating point potential through internal control signals.
Solution Approach 2:
The comparator circuit is designed to generate and apply the necessary voltage drop internally using its own components. This self-service approach eliminates the need for additional external circuits, reducing bill of materials costs and simplifying assembly processes, thus lowering manufacturing costs while preserving adaptability.
3Ease of operation
If the voltage drop mechanism is connected between the differential pair and current mirror, then the operating point potential can be easily modified, but the circuit structure becomes more complex
Solution Approach 1:
The voltage control function is extracted as a separate, modular voltage drop mechanism that can be independently adjusted via control signal. This extracted module is then integrated at a specific point in the comparator circuit (between differential pair and current mirror), allowing easy modification of the operating point potential without requiring complex redesign of the entire circuit structure.
Solution Approach 2:
The voltage drop mechanism acts as an intermediary element between the differential pair and current mirror. By introducing this intermediate component that can be controlled independently, the system achieves easy adjustability of the operating point potential while maintaining the functional integrity of the original comparator architecture, thus balancing ease of operation with structural simplicity.
Data Source
AI summary
The present technology relates to a comparator that can easily modify operating point potential of the comparator, and an imaging device. A pixel signal output from a pixel, and, a reference signal with changeable voltage are input to a differential pair. A current mirror connected to the differential pair, and a voltage drop mechanism allowed to cause a predetermined voltage drop is connected between a transistor that configures the differential pair, and a transistor that configures the current mirror. A switch is connected in parallel to the voltage drop mechanism. The present technology can be applied, for example, to an image sensor that captures an image.