Light Receiving Element Bias Electrode Capacitor Integration
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Solution Overview
Problem
The existing light receiving elements face issues with electric field coupling distortion due to resonance, caused by the enlarged electrical length between the bias electrode of the light receiving element and the integrated circuit, leading to deteriorated characteristics.
Innovation Solution
A light receiving element with a photodiode, signal electrode, and bias electrode is designed to include an insulating film and a metal electrode forming a thin capacitor, reducing the electrical length and minimizing resonance-induced distortion by enabling AC-coupling between the bias electrodes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the bias electrode is connected via a separate capacitor element, then AC-coupling between bias electrodes is achieved, but the electrical length is enlarged causing resonance distortion
Solution Approach 1:
The capacitor is integrated directly onto the bias electrode structure, merging the capacitor element with the electrode itself. This integration eliminates the need for separate capacitor components and their associated connection paths, thereby shortening the electrical length while maintaining the AC-coupling function between the light receiving element's bias electrode and the integrated circuit's bias electrode.
Solution Approach 2:
The capacitor is formed in the vertical dimension by stacking the insulating film and metal electrode layers directly on top of the bias electrode. This vertical integration approach reduces the horizontal electrical path length, effectively shortening the electrical length between bias electrodes while preserving the coupling capability.
2Reliability
If the electrical length between bias electrodes is shortened, then resonance distortion is reduced, but the structure becomes more complex with additional insulating film and metal electrode layers
Solution Approach 1:
The capacitor structure is segmented into distinct functional layers (insulating film layer and metal electrode layer) that are systematically arranged on the bias electrode. This segmentation allows for modular fabrication and integration, managing structural complexity through organized layering while achieving the shortened electrical length necessary to reduce resonance distortion.
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 configuration effectively reduces electric field coupling distortion, allowing for broader bandwidth signal transmission by shortening the electrical path and improving the overall performance of the light receiving element.
Implementation Method 1
both were connected to each other via a capacitor that is a different element
Implementation Method 2
an electric field coupling is distorted by resonance
Data Source
AI summary
A light receiving element comprises: a photodiode including an optical waveguide, an end surface of the optical waveguide being a light receiving surface of the photodiode; a signal electrode and a bias electrode on a common surface of the photodiode, the signal electrode being connected to an anode of the photodiode, the bias electrode being connected to a cathode of the photodiode; an insulating film on the bias electrode; and a metal electrode on the insulating film.