Single-Amplifier Pre-Sampling Circuit for Echo Cancellation
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Solution Overview
Problem
High-speed Ethernet networks face echo signal interference and require programmable gain and filtering, which existing solutions fail to address cost-effectively with low noise and high linearity.
Innovation Solution
A pre-sampling device with a single amplifier and feedback circuit featuring a virtual ground node, programmable switches, and an adjustable current source for echo signal cancellation, along with anti-alias filtering, minimizes echo signals and provides programmable gain.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If multiple amplifiers are used to provide programmable gain and filtering, then signal processing capability is improved, but device complexity and cost increase
Solution Approach 1:
The single amplifier is designed to perform multiple functions including programmable gain control through switchable feedback paths, echo cancellation through adjustable current sources, and anti-aliasing filtering through RC networks. This multi-functional design eliminates the need for separate amplifiers for each function, thereby reducing device complexity while maintaining signal processing capability
Solution Approach 2:
The patent combines gain control, echo cancellation, and filtering functions into a single amplifier circuit. The feedback circuit integrates multiple control mechanisms that work together within one amplifier stage, merging what would traditionally require multiple separate amplifier stages into a unified circuit architecture
2Reliability
If multiple amplifiers are used for signal processing, then linearity is improved, but cost increases
Solution Approach 1:
The amplifier employs a feedback circuit with switchable feedback paths that allow precise control of the amplifier's operation. The feedback mechanism compensates for non-linearities and maintains high linearity performance. Additionally, an adjustable current source provides echo cancellation through feedback, further improving signal fidelity without requiring multiple amplifiers
Solution Approach 2:
The circuit uses switchable RC networks that change the electrical parameters of the feedback paths to achieve different filtering characteristics and gain settings. By dynamically changing circuit parameters rather than using multiple fixed amplifiers, the design maintains linearity across different operating conditions while reducing component count and cost
3Reliability
If echo cancellation is implemented, then signal quality is improved, but device complexity increases
Solution Approach 1:
The adjustable current source acts as an intermediary element that generates an echo cancellation signal. This current source is controlled by a scaled version of the transmit signal and injects a canceling current at the amplifier's virtual ground, effectively eliminating echo without requiring a separate echo cancellation amplifier or complex additional circuitry
Solution Approach 2:
The echo cancellation function is merged into the main amplifier's feedback circuit. The adjustable current source is integrated with the amplifier's virtual ground node, allowing echo cancellation to occur within the same circuit stage that performs gain control and filtering, thereby avoiding additional device complexity
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 reduces echo signal interference, improves linearity, and is cost-effective by using a single amplifier for preprocessing signals before sampling in Ethernet transceivers.
Implementation Method 1
A current of the adjustable current source is summed at the virtual ground node. The feed back circuit also includes an adjustable current source that is adjusted according to an estimated echo signal
Implementation Method 2
The feed back circuit also includes a low pass filter that is tuned to suppress received signal frequencies above a fraction of a sampling frequency of a sampler connected to the pre-sampling device
Data Source
AI summary
An device and method for a pre-sampling processing is disclosed. The pre-sampling device includes a single amplifier having a virtual ground node, and a feed back circuit connected from an output of the amplifier to the virtual ground node. The feed back circuit includes a plurality of switches connected to the virtual ground node. The switches control a plurality of programmable gain settings. The feed back circuit also includes an adjustable current source that is adjusted according to an estimated echo signal. A current of the adjustable current source is summed at the virtual ground node. The feed back circuit also includes a low pass filter that is tuned to suppress received signal frequencies above a fraction of a sampling frequency of a sampler connected to the pre-sampling device.