Low-Noise Comparator With Vertical Channel Transistors

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Solution Overview

Problem

Existing methods for reducing noise in comparator circuits of solid-state imaging apparatuses, such as CMOS image sensors, are insufficient in effectively minimizing noise characteristics.

Innovation Solution

A comparator design that includes a differential circuit with transistors having channel regions perpendicular to the substrate surface and an active load circuit with transistors having uneven shapes along the channel length direction, along with specific transistor types and crystal plane orientations, to enhance noise reduction.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Object-affected harmful factors

If the size of input transistor and reference transistor are made different, then noise is reduced, but manufacturing precision deteriorates

Engineering Contradiction:

ImprovenoiseVSAvoidtransistor size control precision

Core Design Contradiction:

Object-affected harmful factorsVSManufacturing precision

Solution Approach 1:

The patent changes the geometric parameters of the transistor channel regions by introducing uneven shapes (ridges or grooves) along the channel length direction. This modifies the effective channel length while maintaining the same physical transistor dimensions, thereby reducing noise without requiring different transistor sizes that would compromise manufacturing precision

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent extends the channel region in the vertical direction by creating uneven shapes (ridges protruding upward or grooves extending downward) along the channel length direction. This three-dimensional structure increases the effective channel length without increasing the planar footprint, achieving noise reduction while maintaining consistent transistor dimensions for precise manufacturing

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

2Object-affected harmful factors

If transistors are made with uneven channel shapes, then noise reduction is enhanced, but device complexity increases

Engineering Contradiction:

ImprovenoiseVSAvoidtransistor structure complexity

Core Design Contradiction:

Object-affected harmful factorsVSDevice complexity

Solution Approach 1:

The patent introduces curved or uneven channel shapes (ridges or grooves) along the channel length direction instead of straight channels. This geometric modification increases the effective channel length and reduces noise while maintaining a relatively simple fabrication process that can be integrated into existing CMOS manufacturing

Inventive Principle:

Principle #14Spheroidality (Curvature)

Data Source

PatentUS20250330727A1Comparator, light detection element, and electronic device

Publication Date: 2025.10.23 SONY SEMICON SOLUTIONS CORP

AI summary

A comparator, a light detection element, and an electronic device that reduce noise are disclosed. In one example, a comparator is configured to compare a signal with a reference signal and to output a comparison result. The comparator includes a differential circuit that outputs a differential voltage between the signal and the reference signal; and an active load circuit electrically connected to the differential circuit, in which the differential circuit includes first and second transistors provided on a surface of a substrate, and the first and second transistors have channel regions extending in a direction substantially perpendicular to the surface of the substrate.