Optical Receiver Circuit Layout for Low-Impedance Bonded Interconnects
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Solution Overview
Problem
Conventional optical receiver circuits face issues with increased impedance and degradation of high-frequency transmission characteristics due to the presence of bonding wires, which can lead to resonance, radiation noise, and crosstalk, especially in multichannel configurations.
Innovation Solution
The optical receiver circuit incorporates a light-receiving element with anode and cathode electrode pads, and ground pads arranged to sandwich these electrodes, connected by specific electrical conductors to suppress impedance increases and resonance. This configuration allows for a multichannel setup with improved high-frequency characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If bonding wires are used to connect PD chip and TIA chip, then electrical connection is achieved, but impedance increases and high-frequency transmission characteristics degrade
Solution Approach 1:
The patent extracts and removes the bonding wires from the signal transmission path. Instead of using bonding wires to connect the PD chip anode electrode pad to the TIA chip signal input pad, the invention uses a ground pad configuration that eliminates the need for these high-impedance bonding wire connections, thereby removing the source of impedance increase and resonance at high frequencies
Solution Approach 2:
The patent implements equipotentiality by connecting the anode electrode pad and the signal input pad to the same ground potential through the ground pad configuration. This creates an equipotential reference that eliminates voltage differences and reduces impedance effects at high frequencies, allowing the signal to be transmitted without the harmful impedance increases caused by bonding wires
2Illumination intensity
If through-hole is made large for optical signal incidence, then optical signal reception is improved, but return current path is blocked causing bypass current and resonance
Solution Approach 1:
The patent introduces ground pads as intermediary elements between the through-hole and the electrical connections. These ground pads serve as mediators that provide alternative current paths and electromagnetic shielding, preventing the blockage of return current paths while maintaining large through-holes for optimal optical signal reception
Solution Approach 2:
The patent converts the potential harm of large through-holes blocking return current paths into a benefit by using the ground pad configuration to create controlled impedance paths. The large through-holes that would normally cause resonance and radiation noise are transformed into beneficial structures that maintain optical signal reception while the ground pads manage the electrical return paths to prevent harmful effects
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
The proposed solution effectively suppresses unnecessary impedance increases and occurrences of resonance and radiation noise, while maintaining preferable high-frequency transmission characteristics, even in multichannel configurations.
Implementation Method 1
a light-receiving element which converts an optical signal into an electrical signal
Data Source
AI summary
In an optical receiver circuit which suppresses an unnecessary increase in impedance and occurrences of resonance and radiation noise and which produces preferable high-frequency transmission characteristics, a PD submount mounted with a PD chip and a chip capacitor and a TIA carrier mounted with a TIA chip are electrically connected to each other by a bonding wire. The chip includes an anode electrode pad and a cathode electrode pad, anode electrode-side ground pads are formed at positions that sandwich the pad, and cathode electrode-side ground pads are formed at positions that sandwich the pad. A wire electrically connects the pad and a signal pad for input of the chip to each other, a wire electrically connects the pad and the capacitor to each other, and a wire electrically connects the pads and the pads to each other.