Differential Receiver Circuit for Uneven Common-Mode Noise Rejection
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Solution Overview
Problem
Conventional common-mode rejection techniques in differential receivers fail to effectively handle uneven noise coupling, where noise does not couple evenly to both signals of a differential pair, leading to system failures and increased complexity and cost in noise suppression.
Innovation Solution
A common-mode rejection circuit with two differential receivers monitoring both terminals of a differential pair, outputting out-of-phase signals that are summed by an amplifier to cancel common-mode noise, and using clamping circuits to limit signal amplitude and maintain signal integrity, allowing for effective suppression of differential mode noise.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If conventional differential amplifiers are used to suppress common-mode noise, then common-mode noise rejection is improved, but uneven noise coupling to differential pairs cannot be compensated
Solution Approach 1:
The single differential amplifier is segmented into two separate differential amplifiers, each dedicated to monitoring one terminal of the differential pair. This segmentation allows each amplifier to independently process signals from its respective terminal, enabling separate gain adjustment for each path to compensate for uneven noise coupling.
Solution Approach 2:
The invention changes the gain parameter of each differential amplifier independently through adjustable resistors. By varying the gain of each amplifier separately, the system can compensate for differences in noise coupling to each terminal, transforming a fixed-parameter system into an adjustable one that adapts to uneven noise conditions.
2Reliability
If noise suppression techniques are implemented to handle uneven noise coupling, then system reliability is improved, but device complexity increases
Solution Approach 1:
Each differential amplifier serves multiple functions: it monitors common-mode noise at its terminal, amplifies the differential signal, and provides adjustable gain compensation for uneven noise coupling. This multi-functionality reduces the need for additional dedicated compensation circuits, thereby limiting the increase in overall device complexity.
Solution Approach 2:
The system implements feedback through adjustable resistors that allow monitoring and correction of gain imbalances. This feedback mechanism enables the system to automatically compensate for uneven noise coupling without requiring complex external control circuits, maintaining relatively simple device architecture while improving reliability.
3Stability of the object's composition
If clamping circuits are added to limit signal swing, then signal integrity is improved, but normal signal swing is reduced
Solution Approach 1:
Clamping circuits are applied locally only to the differential mode signal paths where needed, rather than to the entire signal chain. The clamping diodes are positioned to affect only the differential signal component, leaving the common-mode rejection and overall signal integrity preservation functions unaffected, thus minimizing the impact on normal signal swing.
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 cancels and suppresses uneven noise coupling, ensuring the receiver output has minimal noise, regardless of whether noise is coupled to the positive or negative side, thereby improving system reliability and reducing complexity and cost.
Implementation Method 1
The two receivers are designed to output two out of phase signals, and the outputs of these are inputs to a summing amplifier. In this implementation, the summing amplifier cancels the common-mode noise.
Implementation Method 2
The circuit may use diodes to clamp the voltage swing of one receiver path to allow for normal signals propagating through the circuit.
Data Source
AI summary
A common-mode rejection receiver including a first differential amplifier arranged to receive a differential signal including receiving a positive signal of the differential signal at a first non-inverting input port and receiving a negative signal of the differential signal at a first inverting input port, and output a first differentiated signal based on a voltage differential between the positive signal and the negative signal. A clamping circuit is arranged to limit a magnitude of the first differentiated signal to a pre-determined limit. A second differential amplifier is arranged to receive the positive signal at a second inverting input port and receive the negative signal at a second non-inverting input port, and output a second differentiated signal. A matching circuit is arranged to receive the second differentiated signal output and output a matched signal. A summing circuit adds the clamped signal and matched signal and outputs a receiver output signal.