Discrete-Time Filter Feedback Switching for Q Control
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Solution Overview
Problem
Existing discrete-time filters face challenges in controlling the quality factor (Q value), which affects the stability of the output signal, and require additional circuits that introduce noise and increase costs when adjusting feedback coefficients.
Innovation Solution
The proposed solution involves a discrete-time filter design that includes a transconductance circuit, a switched-capacitor filter circuit, and adjustable sampling capacitors, allowing for flexible adjustment of the feedback coefficient by changing the connection of the second sampling capacitor to the switch, thereby implementing no feedback or negative feedback.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a feedback circuit is added to control the Q value of the discrete-time filter, then the quality factor control is improved, but the device complexity increases and additional noise is introduced
Solution Approach 1:
The patent combines the feedback coefficient adjustment function with the existing sampling capacitor structure. The second sampling capacitor is reconfigured to serve dual purposes: normal sampling operation and feedback coefficient adjustment. By switching the connection terminals of the second sampling capacitor, the feedback coefficient can be adjusted without adding separate feedback circuits, thus reducing device complexity while maintaining quality factor control capability.
Solution Approach 2:
The second sampling capacitor is designed to perform multiple functions: it acts as a sampling capacitor during normal operation and simultaneously serves as a feedback element when its connection is switched. This multi-functional design eliminates the need for dedicated feedback circuits, reducing overall circuit complexity while maintaining the ability to control the quality factor of the discrete-time filter.
2Manufacturing precision
If a feedback circuit is added to control the Q value of the discrete-time filter, then the quality factor control is improved, but noise is introduced
Solution Approach 1:
The patent merges the feedback function with the existing sampling capacitor, eliminating the need for separate feedback circuits that would introduce additional noise. By using the second sampling capacitor for both sampling and feedback purposes, the design avoids adding new active components that generate noise, thus maintaining signal quality while achieving quality factor control.
Solution Approach 2:
The second sampling capacitor serves itself by being reconfigured to provide feedback functionality. Instead of requiring external feedback circuits, the existing capacitor structure is utilized for dual purposes, reducing the introduction of external noise sources while maintaining the ability to control the quality factor.
3Adaptability or versatility
If additional circuits are added to adjust the feedback coefficient, then the feedback coefficient adjustment flexibility is improved, but the costs increase
Solution Approach 1:
The patent combines the feedback coefficient adjustment capability with the existing sampling capacitor structure. By switching the connection terminals of the second sampling capacitor, different feedback coefficients can be achieved without adding extra circuits. This approach maintains adjustment flexibility while reducing manufacturing costs by utilizing existing components for multiple functions.
Solution Approach 2:
The second sampling capacitor is designed to perform multiple functions including sampling and feedback coefficient adjustment. This multi-functional design eliminates the need for additional adjustment circuits, reducing component count and manufacturing complexity while maintaining the flexibility to adjust feedback coefficients for different quality factor requirements.
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 design improves the flexibility of feedback coefficient adjustment while maintaining filter performance, reduces noise, and lowers costs by eliminating the need for additional circuits.
Implementation Method 1
a switched-capacitor filter circuit, a first sampling capacitor, a second sampling capacitor
Implementation Method 2
an output end of the transconductance circuit is connected to a first node through the switched-capacitor filter circuit
Data Source
AI summary
A discrete-time filter includes a transconductance circuit, a switched-capacitor filter circuit, a first sampling capacitor, a second sampling capacitor, and a switch, where an output end of the transconductance circuit is coupled to a first node through the switched-capacitor filter circuit; both a first end of the first sampling capacitor and a first terminal of the switch are coupled to the first node; and both a second terminal of the switch and a second end of the first sampling capacitor are grounded. The second sampling capacitor is coupled to the switch such that sampling is implemented and negative feedback is provided by switching connection ends of the switch to adjust a feedback coefficient.