Optical Modulator Electrode Pad Matrix Design
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Solution Overview
Problem
Existing optical integrated devices and modulators face challenges in downsizing due to large wire bonding electrode pads, which increase inductance and degrade frequency response characteristics, and bent signal lines cause skew differences and return loss issues.
Innovation Solution
The optical modulator design includes Mach-Zehnder units with strategically positioned signal and ground electrode pads, where the ground pads are displaced by less than a specific interval from signal pads, and signal wiring portions extend to separate gradually from the center line, reducing return loss and improving frequency response.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If wire bonding electrode pads are arranged in a line along the short side of the optical integrated device, then electrical connection is achieved, but the device size increases and downsizing is prevented
Solution Approach 1:
The electrode pads are arranged in a two-dimensional matrix pattern rather than a one-dimensional line, utilizing both the short side direction and the long side direction of the optical integrated device. This dimensional transition allows for more compact arrangement of the same number of electrode pads, reducing the overall device footprint while maintaining all necessary electrical connections.
2Reliability
If bonding wire diameter is increased to decrease inductance for high-frequency signal transmission, then frequency response improves, but electrode pad size must be enlarged
Solution Approach 1:
The matrix arrangement of electrode pads creates multiple shorter bonding paths in both horizontal and vertical directions, effectively reducing the inductance of bonding wires without requiring larger wire diameters. This two-dimensional distribution of connection points allows high-frequency signals to be transmitted with lower inductance while keeping electrode pads at standard sizes.
3Area of stationary object
If signal lines are bent at right angles for compact routing, then space utilization improves, but skew difference and return loss increase degrading frequency response
Solution Approach 1:
The signal line routing is optimized locally at each electrode pad connection point and along each signal path to maintain consistent electrical characteristics. By carefully designing the local geometry of signal lines connecting to the matrix arrangement of electrode pads, the patent minimizes skew differences and return loss while still achieving compact overall device dimensions through the two-dimensional electrode distribution.
Data Source
AI summary
An optical modulator includes a plurality of Mach-Zehnder optical modulation units. Each of the plurality of Mach-Zehnder optical modulation units include a pair of first signal wirings, a pair of first ground wirings, a pair of first signal electrode pads, and a pair of first ground electrode pads. The pair of first ground electrode pads is displaced by less than the first interval from the pair of first signal electrode pads so as to separate from a center line of each of the plurality of Mach-Zehnder optical modulation units.