Optical Modulator Connection Substrate With Integrated Bias-Blocking Capacitor
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Solution Overview
Problem
In optical circuits using flip-chip mounting, the mounting of a capacitor necessary for applying a bias voltage is a challenge in terms of miniaturization and reliability, as it requires additional space and can lead to connection breakage during wire bonding.
Innovation Solution
An optical circuit configuration that includes a connection substrate with a termination resistor and a capacitor connected to the ground in series with the termination resistor, which blocks the bias current and reduces power consumption, while being mounted on the connection substrate to avoid the need for wire bonding and maintain miniaturization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a capacitor is mounted on the subcarrier using wire bonding in flip-chip mounting, then the optical circuit can apply bias voltage, but the device size increases and connection reliability decreases due to wire bonding breakage
Solution Approach 1:
The patent merges the capacitor mounting with the connection substrate by forming the capacitor directly on the connection substrate using conductive patterns. This eliminates the need for separate wire bonding operations and additional mounting steps, thereby improving connection reliability while reducing device complexity.
Solution Approach 2:
The connection substrate serves as an intermediary that integrates both the termination resistor and capacitor functions. By forming these components directly on the connection substrate through conductive patterns, the patent eliminates the need for separate wire-bonded capacitor mounting, thus improving reliability and reducing mounting complexity.
2Use of energy by moving object
If a capacitor is mounted using wire bonding, then bias voltage can be applied, but power consumption increases and miniaturization is hindered
Solution Approach 1:
The patent combines the capacitor function with the connection substrate structure by forming capacitive elements directly on the substrate using conductive patterns. This integration eliminates the need for separate discrete capacitor components and their associated wire bonding, thereby reducing overall device volume while maintaining the bias voltage application function.
Solution Approach 2:
The patent changes the physical form and location of the capacitor from a discrete component mounted via wire bonding to an integrated conductive pattern formed directly on the connection substrate. This parameter change enables miniaturization and reduces power consumption by eliminating parasitic inductance from wire bonds.
3Ease of manufacture
If wire bonding is used for capacitor mounting, then electrical connection is achieved, but manufacturing reliability decreases due to connection breakage
Solution Approach 1:
The connection substrate acts as an intermediary that integrates both termination resistor and capacitor functions through conductive patterns formed directly on the substrate. This eliminates the need for separate wire bonding operations, thereby improving manufacturing reliability and connection reliability simultaneously.
Solution Approach 2:
The connection substrate provides self-service by forming both the termination resistor and capacitor functions through its own conductive patterns. This self-integration eliminates the need for external wire bonding operations, improving both manufacturing and connection reliability.
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 optical circuit achieves high-speed operation with a miniaturized and reliable optical modulator, reducing power consumption by one-third compared to configurations without a capacitor, while maintaining equivalent bandwidth and peaking in modulation frequency characteristics.
Implementation Method 1
a capacitor connected to the ground in series with the termination resistor on the connection substrate
Data Source
AI summary
A novel mounting form of a capacitor for blocking a bias voltage in an optical circuit including an optical chip including an optical modulator, a wiring board that supplies a high-frequency electrical signal, and a connection substrate that connects the optical chip and the wiring board is disclosed. A wiring board and a light-modulating light source chip are mounted on a subcarrier. The wiring board and the light-modulating light source chip are connected by a connection substrate, and a high-frequency electrical signal is input to a modulation input electrode from the outside of the optical circuit. The connection substrate includes a termination resistor on a first surface connected to two substrates by gold bumps. One electrode of the termination resistor is connected to an end of a transmission line on the modulation input electrode side. The other electrode of the termination resistor is connected to a high impedance line.