Feedback Duty Cycle Correction Circuit for Noise-Distorted Signals
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Solution Overview
Problem
Duty cycle distortion due to ground shift or noise during communication can lead to communication failures, especially when the absolute average duty cycle distortion exceeds 30%, resulting in a higher than desirable bit-error rate in signal decoding circuits.
Innovation Solution
A duty cycle correction circuit comprising an input stage, an output stage, and a feedback component with a feedback amplifier and low pass filter, which adjusts the duty cycle of a signal to a target value by comparing and filtering noise, thereby reducing rise and fall times and amplifying the signal to maintain a stable duty cycle.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the duty cycle of a signal is measured during communication, then the duty cycle information can be used for signal decoding, but the duty cycle becomes distorted due to ground shift or noise
Solution Approach 1:
The patent employs a feedback mechanism where the duty cycle of the received signal is continuously monitored, and correction voltages are applied based on the measured duty cycle deviation from the target value. The feedback amplifier compares the actual duty cycle with the target duty cycle and generates a correction signal that is fed back to the input stage to adjust the signal waveform, thereby compensating for ground shift and noise distortion effects.
Solution Approach 2:
The patent changes the parameter of the signal by applying a correction voltage to the input stage that modifies the duty cycle parameter of the received signal. The feedback amplifier generates a correction voltage proportional to the duty cycle error, and this voltage is applied to adjust the signal waveform parameters (rise time, fall time, pulse width) to achieve the target duty cycle.
2Reliability
If the absolute average duty cycle distortion exceeds 30%, then communication failure occurs, but reducing distortion requires complex correction circuits
Solution Approach 1:
The feedback mechanism continuously monitors the duty cycle and automatically generates correction signals, providing a self-regulating system that maintains communication reliability without requiring complex external control logic. The feedback amplifier and low-pass filter form a compact correction circuit that achieves reliable duty cycle maintenance through automatic adjustment.
Solution Approach 2:
The correction circuit performs self-service by automatically detecting duty cycle deviations and generating its own correction signals without external intervention. The feedback amplifier compares the actual duty cycle with the target and autonomously produces the necessary correction voltage, making the system self-regulating and reducing the need for complex external control mechanisms.
3Measurement precision
If rise and fall times are reduced to increase duty cycle sensitivity, then the duty cycle becomes more responsive to control voltage, but the circuit may amplify noise
Solution Approach 1:
The low-pass filter is placed in the feedback path to preliminarily filter out high-frequency noise components before the feedback amplifier processes the duty cycle error signal. This preliminary filtering action prevents noise amplification while allowing the circuit to maintain high duty cycle sensitivity to legitimate control signals.
Solution Approach 2:
The low-pass filter acts as an intermediary between the noisy received signal and the feedback amplifier. It mediates by selectively attenuating high-frequency noise components while passing the relevant duty cycle information, thereby protecting the feedback amplifier from amplifying noise while maintaining sensitivity to legitimate duty cycle variations.
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 duty cycle correction circuit effectively filters noise and adjusts the duty cycle to prevent communication failures by maintaining the average signal value close to half the power supply voltage, reducing bit-error rates and ensuring reliable communication.
Implementation Method 1
a feedback component including a feedback amplifier and a low pass filter. The feedback component compares and adjusts the duty cycle of a signal from an input stage to a target value via a control voltage
Implementation Method 2
The feedback amplifier also amplifies the difference between the signal duty cycle to a target duty cycle by subtracting a signal received at the output of the output stage amplifier from the reference voltage and amplifying the subtracted signal according to a predefined DC gain of the feedback amplifier
Implementation Method 3
The input stage reduces the rise and fall times of received signal to increase the duty cycle sensitivity to a control voltage from the feedback component
Data Source
AI summary
A duty cycle correction circuit is disclosed. The duty cycle correction circuit includes an input stage, an output stage and a feedback component including a feedback amplifier and a low pass filter. The feedback component compares and adjusts the duty cycle of a signal from an input stage to a target value via a control voltage. The input stage reduces the rise and fall times of received signal to increase the duty cycle sensitivity to a control voltage from the feedback component. The output of the output stage is coupled to the input of the feedback component and the output stage amplifiers the duty cycle adjusted signal processed by both input stage and feedback component.