Self-Limiting Comparator Feedback for Fast Low-Power Transitions
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Solution Overview
Problem
Comparators in integrated circuits often exhibit slow transitions between output states, which is not suitable for modern electronic circuits requiring increased speed, and they also consume high power due to uncontrolled positive feedback.
Innovation Solution
A comparator circuit with a feedback loop that includes a feedback limiting circuit to attenuate the positive feedback signal, using an amplifier and a non-linear function with a MOSFET and capacitor to rapidly transition between output states while minimizing power consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If positive feedback is applied to increase transition speed, then the comparator achieves rapid transitions between output states, but power consumption increases due to uncontrolled feedback signal
Solution Approach 1:
The patent introduces a feedback limiting circuit as an intermediary component between the output and the non-linear function. This circuit selectively limits the feedback signal to prevent excessive power consumption while preserving the speed-enhancing effects of positive feedback during transitions.
Solution Approach 2:
The feedback limiting circuit dynamically changes the feedback signal parameter (amplitude/strength) based on operating conditions. During transitions, full feedback is allowed for rapid switching; during stable states, feedback is limited to minimize power consumption.
2Speed
If high-gain amplifier is used to increase transition speed, then the comparator responds quickly, but the circuit complexity increases
Solution Approach 1:
The patent segments the feedback path into two functional parts: the main feedback loop for speed enhancement and the feedback limiting circuit for power control. This segmentation allows independent optimization of each function without requiring a complete redesign of the amplifier structure.
Solution Approach 2:
The feedback limiting circuit acts as an intermediary that mediates between the high-gain amplifier's need for full feedback and the power consumption constraints. It provides the necessary feedback signal conditioning without requiring changes to the core amplifier design.
Data Source
AI summary
A method and circuit for attenuating positive feedback in a comparator in one embodiment includes an amplifier configured to compare a first input signal with a second input signal and to provide an output based upon the comparison, a non-linear function with a first input operably connected to an output of the amplifier, and a feedback loop operably connected to the output of the non-linear function and to a second input of the non-linear function, the feedback loop including a feedback limiting circuit configured to attenuate a feedback signal to the second input of the non-linear function.