Optical Receiver Layout for Resonance-Free TIA Wire Connection
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Solution Overview
Problem
The increasing frequency of optical signals due to higher speed communication leads to resonance frequencies in the connection between the light receiving element and the TIA, causing non-transmission bands and degradation of signal waveforms and communication quality, while flip-chip bonding requires dedicated TIAs, increasing manufacturing costs.
Innovation Solution
The optical receiver design includes a conductor with smaller inductance connected in parallel with parasitic capacitance, and an electrostatic capacitance in series, shifting the resonance frequency to lower bands, and uses a chip capacitor with a dielectric layer to enhance electrostatic capacitance, reducing electromagnetic coupling and connection loss.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If wire connection is used between light receiving element and TIA, then manufacturing cost is reduced, but resonance frequency occurs causing non-transmission bands and signal degradation
Solution Approach 1:
A capacitor is introduced as an intermediary component between the light receiving element and the TIA. This capacitor has an electrostatic capacitance larger than the parasitic capacitance between the first and second conductive films, and is connected with inductance smaller than the wire inductance. This intermediary component shifts the resonance frequency to a lower band, removing it from the signal transmission band while maintaining wire connection for cost-effectiveness.
Solution Approach 2:
The patent changes the electrical parameters of the connection path by introducing a capacitor with specific electrostatic capacitance and inductance values. The capacitor's electrostatic capacitance is designed to be larger than the parasitic capacitance between conductive films, and its inductance is designed to be smaller than the wire inductance. This parameter change shifts the resonance frequency f = 1/(2π√(LC)) to a lower frequency, resolving the contradiction between using simple wire connection and avoiding signal degradation.
2Loss of energy
If flip-chip bonding is used to reduce inductance, then connection loss is reduced, but dedicated TIAs are required increasing manufacturing cost
Solution Approach 1:
The capacitor serves as an intermediary that compensates for the high inductance of wire connections. By introducing this component with carefully controlled inductance and capacitance values, the system achieves resonance frequency shifting without requiring flip-chip bonding, thus maintaining manufacturing simplicity while reducing connection loss through optimized electrical characteristics.
Solution Approach 2:
Instead of using expensive dedicated TIAs designed for flip-chip bonding, the patent uses a standard TIA combined with a capacitor that replicates the electrical performance benefits of flip-chip bonding. The capacitor copy's electrical characteristics (low inductance, high electrostatic capacitance) compensate for the wire connection's deficiencies, achieving similar performance to flip-chip bonding at lower cost.
3Device complexity
If wire connection with parasitic capacitance is used, then device complexity is reduced, but resonance frequency causes non-transmission bands
Solution Approach 1:
The capacitor is introduced as a mediating component that addresses the resonance issue without complicating the overall connection structure. It is integrated into the existing wire connection architecture, adding only one additional component while significantly improving signal transmission quality by shifting the resonance frequency away from the operational band.
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 suppresses communication quality degradation by removing non-transmission bands and reducing electromagnetic interference, allowing for efficient signal transmission in high-frequency bands without increasing manufacturing costs.
Implementation Method 1
an electrostatic capacitance between the second conductive film and the main surface of the base is larger than a parasitic capacitance between the first conductive film and the second conductive film
Implementation Method 2
a capacitor having a dielectric layer, and a first metal film and a second metal film provided so as to vertically interpose the dielectric layer therebetween
Implementation Method 3
The inductance of the conductor is smaller than the inductance of the first wire
Data Source
AI summary
An optical receiver includes a light receiving element, a capacitor, a transimpedance amplifier, and a base. The light receiving element includes a semiconductor layer, a first conductive film electrically connected to a cathode electrode, a second conductive film electrically connected to the first conductive film through a conductor, and an anode pattern electrically connected to an anode electrode. The transimpedance amplifier has a first pad electrically connected to the first conductive film through a first wire and a second pad electrically connected to the anode pattern through a second wire. The base has a main surface. An electrostatic capacitance between the second conductive film and the main surface of the base is larger than a parasitic capacitance between the first conductive film and the second conductive film, and the inductance of the conductor is smaller than the inductance of the first wire.