Comparator Input Filter Network for Kickback Noise Cancellation
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Solution Overview
Problem
Comparators in devices like integrated circuits or printed circuit boards experience output interference due to unequal kickback noise when processing input signals with different frequencies, as the existing technologies fail to effectively cancel out this noise.
Innovation Solution
A passive filter network is implemented to equalize the impedance at the inputs of the comparator, ensuring that the kickback noise is equalized across both inputs, thereby canceling out the noise and minimizing its impact on the output.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a comparator processes input signals with different frequencies, then the comparator can handle diverse signal types, but unequal kickback noise is injected into the inputs causing output interference
Solution Approach 1:
A passive filter network is introduced as an intermediary component between the input signals and the comparator inputs. This filter network equalizes the impedance at both comparator inputs, ensuring that kickback noise is injected equally and can be canceled out, while still allowing the comparator to process different frequency signals.
Solution Approach 2:
The filter network changes the impedance parameter at the comparator inputs to achieve equality. By adjusting the filter components (resistors and capacitors), the impedance seen by both inputs is equalized at the kickback noise frequency, transforming the unequal noise injection into equal noise injection that cancels out.
2Adaptability or versatility
If drivers with different output impedances are used to drive comparator inputs, then the comparator can interface with different signal sources, but unequal kickback noise is generated
Solution Approach 1:
The passive filter network serves as a mediator that compensates for the different output impedances of the drivers. By placing the filter network at the comparator input with different impedance values on each side, it equalizes the total impedance seen by the kickback noise, ensuring equal noise injection despite different driver impedances.
Solution Approach 2:
The filter network intentionally uses asymmetric component values (different resistors and capacitors on each input side) to compensate for the asymmetric driver impedances. This asymmetric design creates symmetric total impedance at the comparator inputs, equalizing the kickback noise injection.
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 solution effectively mitigates the effects of unequal kickback noise by ensuring that the impedance at both inputs matches, resulting in little to no impact on the comparator's output, even when processing input signals with different frequencies.
Implementation Method 1
the passive filter network is configured to perform impedance matching such that an impedance seen from a perspective of the first input of the comparator matches an impedance seen from a perspective of the second input of the comparator
Implementation Method 2
selecting a capacitance for a filter network that generates an AC ground at the kickback noise frequency
Data Source
AI summary
Embodiments herein describe placing a filter network at one of the inputs of the comparator to avoid injecting unequal amounts of kickback noise into the inputs of the comparator. In one embodiment, the filter network matches the impedance seen at the inputs of the comparator. As a result, the amount of kickback noise is essentially equal at the inputs even though the input signals may be at different frequencies. Thus, the kickback noise is essentially cancelled out so that this noise has little to no impact on the output of the comparator.