Differential Amplifier Feedback for Wideband Common-Mode Suppression
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Solution Overview
Problem
Modern electronic devices face challenges in suppressing wideband common mode interference, which can degrade communication performance and cause hardware damage due to non-linear amplification of common mode signals, especially in complex networks with varying interference sources.
Innovation Solution
A differential amplifier system with integrated feedback networks that inject common mode signals into existing amplifier stages, using both direct and capacitive coupling to suppress common mode interference, reducing the need for dedicated amplifiers and minimizing die area, power use, and complexity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a dedicated common mode amplifier is used to suppress common mode signals, then common mode suppression performance is improved, but device complexity and die area increase
Solution Approach 1:
The patent combines the common mode suppression function with the existing differential amplifier by injecting common mode signals into the differential amplifier stages. This merging approach eliminates the need for a separate dedicated common mode amplifier, thereby reducing device complexity and die area while maintaining common mode suppression performance.
Solution Approach 2:
The differential amplifier is designed to perform multiple functions: both differential signal amplification and common mode suppression. By injecting common mode signals into the differential amplifier stages and utilizing its existing circuitry, the system achieves common mode rejection without requiring additional dedicated components, thus实现ing multi-functionality with a single amplifier structure.
2Reliability
If a dedicated common mode amplifier is used to suppress common mode signals, then common mode suppression performance is improved, but power consumption increases
Solution Approach 1:
The patent merges the common mode suppression function into the existing differential amplifier, which is already powered and operational. By reusing the same power supply and circuitry for both differential amplification and common mode suppression, the system avoids the additional power consumption that would result from operating a separate dedicated common mode amplifier.
Solution Approach 2:
The differential amplifier serves itself by handling both differential signal processing and common mode suppression functions. The existing amplifier stages and power infrastructure are utilized to provide common mode rejection, eliminating the need for additional power-consuming dedicated common mode amplification circuitry.
3Reliability
If feedback is capacitively coupled to current sources, then wideband common mode suppression is improved, but circuit complexity increases
Solution Approach 1:
The feedback network is segmented into multiple coupling points: direct coupling to the first amplifier stage for low-frequency common mode suppression, and capacitive coupling to current sources for high-frequency suppression. This segmentation allows each coupling method to target specific frequency ranges, achieving wideband suppression while keeping individual feedback paths relatively simple.
Solution Approach 2:
Different feedback coupling methods are applied at different locations within the amplifier circuit. Direct coupling is applied at the first amplifier stage where low-frequency common mode signals are predominant, while capacitive coupling is applied at current sources where high-frequency signals need suppression. This localized approach optimizes suppression performance for each frequency band without requiring complex circuitry throughout the entire amplifier.
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 system effectively suppresses common mode interference, improving signal integrity and reducing the risk of hardware damage while optimizing resource usage.
Implementation Method 1
a second pair of feedback inputs capacitively coupled to the first pair of current sources, or a third pair of feedback inputs capacitively coupled to the second pair of current sources
Data Source
AI summary
In some aspects, the disclosure is directed to methods and systems for an amplifier having common mode feedback inputs. The inputs are coupled to various points within an amplifier wherein a first set of directly coupled common mode feedback inputs join the amplifier one or more nodes, and a second set of capacitively coupled common mode feedback inputs are joined to the amplifier at one or more different nodes.