Square-Wave Signal DC Offset Cancellation by Time-Domain Feedback
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Solution Overview
Problem
Existing modulation circuits face inefficiencies and increased complexity due to the presence of DC offsets in modulated signals, which can lead to system performance degradation and measurement errors, requiring additional analog or digital blocks for removal.
Innovation Solution
A time domain processing sequence is applied to estimate and correct DC offsets in modulated signals using integration and differentiation, generating a feedback loop to iteratively subtract the estimated offset, thereby simplifying the removal process and improving area efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If additional analog or digital blocks are added to remove DC offsets, then DC offset removal capability is improved, but device complexity increases
Solution Approach 1:
The patent combines DC offset removal functionality with the existing modulation circuit by integrating a feedback loop that uses the modulated signal itself to generate the correction signal. This eliminates the need for separate analog or digital DC offset removal blocks, thereby reducing device complexity while maintaining DC offset removal capability.
Solution Approach 2:
The modulation circuit performs DC offset removal on its own output signal by using a feedback mechanism. The circuit generates a correction signal based on its own modulated output and applies it to cancel DC offsets, making the system self-correcting without requiring external dedicated removal blocks.
2Measurement precision
If complex DC offset removal blocks are added, then measurement precision is improved, but power consumption increases
Solution Approach 1:
The patent merges DC offset removal functionality into the existing modulation circuit, eliminating the need for separate power-consuming analog or digital removal blocks. The integrated feedback mechanism uses existing circuit resources to achieve offset removal, thereby improving signal accuracy without proportionally increasing power consumption.
3Device complexity
If DC offsets are not removed, then device complexity is reduced, but system performance degrades
Solution Approach 1:
The patent implements a feedback loop where the modulated signal is fed back through a processing path that generates a correction signal. This correction signal is then applied to cancel DC offsets in real-time, ensuring system performance is maintained without requiring complex pre-processing or additional removal blocks.
Solution Approach 2:
The modulation circuit automatically corrects its own DC offset issues through the integrated feedback mechanism, maintaining system performance while keeping the overall device complexity low by using the circuit's own resources for correction.
Data Source
AI summary
Some embodiments of the invention a circuit configured to apply a time domain processing sequence to a modulated input signal to estimate a mean value of the modulated input signal and to subtract the estimated mean value from the modulated input signal, thereby removing the DC offset from the input signal. In one particular embodiment, the time domain processing sequence is based on integration and differentiation of a demodulated output signal. In such an embodiment, a circuit is configured to integrate a demodulated signal to generate an integrated signal having a triangular shaped output signal. The circuit then measures the slopes of the integrated signal, by differentiation of the triangular shaped integrated signal, and generates an appropriate DC offset correction signal based upon the measured slopes. The DC offset correction signal may be added on top of the actual input signal to cancel the unwanted DC offset component.