Inductor-Coupled Gate Modulation for 3D Sensor Power Efficiency
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Solution Overview
Problem
Existing 3D camera technologies face challenges in balancing performance parameters with physical size and power constraints, particularly in time-of-flight systems, which require significant power for gate modulation and struggle with efficient charge transfer in small devices.
Innovation Solution
A time-of-flight sensor system that incorporates an inductor coupled between two gates to recycle gate capacitance power using LC oscillations, reducing resistance and power consumption through pixel-level hybrid bonding and optimized metal line designs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If gate modulation is used to transfer charge in time-of-flight sensors, then charge transfer speed is improved, but power consumption increases significantly
Solution Approach 1:
The patent applies periodic gate modulation at specific frequencies (e.g., 100 MHz, 200 MHz, 400 MHz) to transfer charge from the photodiode to the floating diffusion. By using periodic switching rather than continuous operation, the system achieves fast charge transfer while allowing power management through frequency selection and duty cycle control, directly addressing the contradiction between transfer speed and power consumption
Solution Approach 2:
The patent changes operating parameters including gate modulation frequency, voltage swing amplitude, and timing characteristics to optimize the balance between charge transfer speed and power consumption. Different frequencies are selected based on specific application requirements, allowing the system to adapt parameter values to achieve the desired performance while minimizing power usage
2Measurement precision
If multiple cameras are used for stereo imaging, then 3D image quality is improved, but device size and complexity increase
Solution Approach 1:
The patent replaces the mechanical/optical approach of using multiple physical cameras with an electronic solution using a single time-of-flight sensor. The sensor uses electromagnetic field-based charge detection and time measurement to calculate depth, substituting complex multi-camera mechanical systems with a simpler electronic measurement system that achieves 3D imaging through time-of-flight calculations rather than stereo triangulation
3Productivity
If gate modulation voltage swing is increased to improve charge transfer, then transfer efficiency is improved, but power consumption increases
Solution Approach 1:
The patent uses partial action by applying gate voltage swings only when needed for charge transfer during specific time windows, rather than maintaining continuous high-voltage operation. The gate modulation is applied selectively during the integration period when charge transfer is required, avoiding excessive power consumption during non-active periods while still achieving efficient charge transfer when needed
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 approach enhances the efficiency of charge transfer and reduces power consumption, enabling more compact and power-efficient 3D imaging systems capable of real-time depth calculations.
Implementation Method 1
An inductor is coupled in series between a first gate electrode and a second gate electrode. The inductor applies a first oscillating voltage to the first gate electrode and a second oscillating voltage to the second gate electrode. The first oscillating voltage and the second oscillating voltage are 180 degrees out of phase with each other.
Implementation Method 2
The inductor coupled in series between two gates forms a resonant circuit, utilizing LC oscillation to recycle gate capacitance power when turning the gates on and off.
Data Source
AI summary
A sensor includes a photodiode disposed in a semiconductor material to receive light and convert the light into charge, and a first floating diffusion coupled to the photodiode to receive the charge. A second floating diffusion is coupled to the photodiode to receive the charge, and a first transfer transistor is coupled to transfer the charge from the photodiode into the first floating diffusion. A second transfer transistor is coupled to transfer the charge from the photodiode into the second floating diffusion, and an inductor is coupled between a first gate terminal of the first transfer transistor and a second gate terminal of the second transfer transistor. The inductor, the first gate terminal, and the second gate terminal form a resonant circuit.