Shared Gate Transfer Transistors for Solid-State Imaging Power Reduction
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Solution Overview
Problem
The power consumption of digital cameras with solid-state imaging devices is high due to the need to turn on multiple transfer transistors for each photodiode, increasing energy usage and noise in the imaging process.
Innovation Solution
A semiconductor device with a solid-state imaging system that includes pixels with two photodiodes and transfer transistors, where the transfer transistors TX1 and TX2 are designed to share a gate electrode, allowing simultaneous charging and reducing the need to activate all transistors during imaging, thereby decreasing power consumption and noise.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multiple transfer transistors are provided for each photodiode to enable charge transfer, then charge transfer capability is improved, but power consumption increases
Solution Approach 1:
The patent merges the gate electrodes of multiple transfer transistors (TX1, TX2) into a shared common gate electrode. This allows simultaneous control of multiple transfer transistors with a single electrode, reducing the number of independent gate electrodes needed and thereby reducing power consumption while maintaining charge transfer capability for both photodiodes PD1 and PD2
Solution Approach 2:
The common gate electrode serves multiple functions by controlling both transfer transistor TX1 and transfer transistor TX2 simultaneously. This multi-functional design enables a single gate electrode to manage charge transfer from multiple photodiodes, reducing the overall number of gate electrodes and associated power consumption
2Productivity
If multiple transfer transistors are activated simultaneously for charge transfer, then imaging function is improved, but noise increases
Solution Approach 1:
By merging gate electrodes into a common gate electrode, the patent enables synchronized control of multiple transfer transistors. This simultaneous control allows charge from multiple photodiodes to be transferred at the same time, improving imaging productivity while the coordinated operation reduces noise compared to sequential transfer operations
3Ease of operation
If separate gate electrodes are provided for each transfer transistor, then control flexibility is improved, but device complexity increases
Solution Approach 1:
The patent combines multiple separate gate electrodes into a single common gate electrode that controls multiple transfer transistors. This merging reduces the total number of gate electrodes in the device, simplifying the device structure and reducing complexity while maintaining the ability to control charge transfer operations
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This design reduces power consumption and noise in the imaging process, enabling more efficient and accurate autofocus and imaging operations while maintaining image quality.
Implementation Method 1
a first photodiode and a second photodiode
Data Source
AI summary
A semiconductor device is reduced in power consumption, the semiconductor device including a solid-state imaging device that includes pixels each having a plurality of light receiving elements. A pixel having first and second photodiodes is provided with a first transfer transistor that transfers charge in the first photodiode to a floating diffusion capacitance section, and a second transfer transistor that combines charge in the first photodiode and charge in the second photodiode, and transfers the combined charge to the floating diffusion capacitance section. Consequently, the semiconductor device is reduced in power required for activation of each transfer transistor in operation such as imaging with the solid-state imaging device.