Optical Receiver Bandwidth Switching Without Control Loop Disturbance
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Solution Overview
Problem
Existing control systems with switchable bandwidths face disturbances when changing bandwidth, particularly when reducing capacitance, due to voltage changes and charge equalization between capacitances.
Innovation Solution
A control device with an integrating element, a second capacitance connected in parallel via a switch, and a voltage follower that maintains the voltage across the first capacitance, minimizing disturbances by ensuring both capacitances have the same voltage during switchover.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the second capacitance is connected in parallel with the first capacitance to reduce bandwidth, then the bandwidth of the control system is reduced, but the voltage across the capacitances changes due to charge equalization, causing disturbances to the control loop
Solution Approach 1:
The voltage follower is activated before the second capacitance is connected to pre-charge it to the voltage present at the first capacitance. This preliminary action ensures that when the capacitances are connected in parallel, no charge equalization occurs, thereby preventing voltage changes and control loop disturbances during the bandwidth reduction process
Solution Approach 2:
The voltage follower acts as an intermediary device between the first capacitance and the second capacitance. It transfers the voltage from the first capacitance to the second capacitance before they are connected in parallel, ensuring voltage matching and preventing disturbances to the control loop during the switchover process
2Productivity
If the current charging the integrating element is changed to switch bandwidth, then the bandwidth is switched, but the operating points in circuit parts change greatly, causing disturbances to the control loop
Solution Approach 1:
The invention extracts the bandwidth switching function from the current source that charges the integrating element. Instead of changing the charging current to switch bandwidth, the patent uses a capacitance switching mechanism controlled by a voltage follower, thereby separating the bandwidth control function from the signal processing current path and eliminating operating point changes in circuit parts
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 approach allows for seamless bandwidth reduction without disturbances, as the voltage follower maintains identical voltages across both capacitances, preventing charge equalization and minimizing control loop disruptions.
Implementation Method 1
at least one voltage follower, via which the voltage present at the first capacitance can be fed to the second capacitance
Data Source
AI summary
A control device with a switchable bandwidth including: an integrating element with a first capacitance, which is charged and discharged by at least one current; at least one second capacitance, which can be connected in parallel with the first capacitance via a first switch; and at least one voltage follower, via which the voltage present at the first capacitance can be fed to the second capacitance. In this case, the first switch is open if the voltage present at the first capacitance is fed to the second capacitance by means of the voltage follower. The first switch is closed if the second capacitance is connected in parallel with the first capacitance. The invention enables a further capacitance to be supplementarily connected without a disturbance signal arising.