Optical Switch Driver Timing for Cross-Talk Isolation
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Solution Overview
Problem
Dynamic electrical cross-talk between driver channels in optical switches is significant due to shared ground and supply lines, especially when integrating multiple drivers onto a single chip, making it difficult to compensate using position feedback loops, and existing methods to reduce impedance are limited.
Innovation Solution
Implementing a staggered switching technique where the output voltage is switched in multiple short periods with alternating high-impedance modes for non-switching drivers, effectively isolating channels from cross-talk by sampling previous output values onto channel capacitance, and adjusting switching and re-sampling times to minimize cross-talk without significantly increasing switching time.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If multiple driver circuits share the same electrical supply and ground lines, then device integration is improved, but electrical cross-talk between channels increases
Solution Approach 1:
The patent implements staggered switching where drivers are activated in alternating time periods rather than simultaneously. During each switching period, only one driver switches while others remain in high-impedance mode, creating periodic action that reduces cross-talk while maintaining integration benefits
Solution Approach 2:
The patent applies preliminary action by placing non-switching drivers in high-impedance mode before the switching driver operates. This preparatory high-impedance state prevents cross-talk from affecting non-active channels during the switching event
2Object-affected harmful factors
If the impedance of supply feeds is lowered to reduce cross-talk, then cross-talk is reduced, but close placement of drivers is required which limits further impedance reduction
Solution Approach 1:
By implementing periodic staggering of driver switching operations, the patent reduces cross-talk without requiring increased separation between drivers. The time-domain separation compensates for the spatial proximity, allowing close driver placement while maintaining low cross-talk levels
3Object-affected harmful factors
If position feedback loop bandwidth is increased to compensate for cross-talk, then cross-talk compensation is improved, but the complexity and cost of the feedback system increases
Solution Approach 1:
The patent eliminates the need for complex feedback compensation by preliminarily preventing cross-talk through staggered switching and high-impedance mode. This proactive approach removes the requirement for high-bandwidth feedback loops entirely
Solution Approach 2:
The patent extracts the cross-talk problem from the system by using high-impedance isolation during switching events, removing the need for complex feedback compensation mechanisms
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
Substantially reduces cross-talk voltage between channels while maintaining efficient switching times, even when integrating multiple drivers onto a single chip, by interleaving voltage switching with high-impedance periods for non-switching drivers, thereby controlling the impact of cross-talk on channel voltages.
Implementation Method 1
Piezoelectric actuators are used in a large variety of fields where accurate positioning is required
Implementation Method 2
The cause of the cross-talk is the impedance of the supply/ground feed lines
Implementation Method 3
at least one other driver of at least one other channel is in a relatively high impedance mode
Data Source
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AI summary
An optical switch with a plurality of actuators comprises a controller configured to control the operation of a plurality of channels, where each channel has at least one electrical driver and at least one actuator, by interleaving periods of voltage switching output with periods of no voltage switching output for one or more drivers whilst the output voltage is switching from one level to another level. Alternatively, an optical switch with a plurality of actuators comprises a controller configured to control the operation of a plurality of channels, where each channel has at least one electrical driver and at least one actuator, by switching the output voltage from one level to another level for at least one driver of a first channel whilst at least one other driver of at least one other channel is in a relatively high impedance mode.