Transceiver Echo-Cancellation Circuit for Clock Phase Transients
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Solution Overview
Problem
In full-duplex Ethernet systems, transient echo responses are generated when the phase of the clock signal is changed, affecting system performance and increasing the complexity of phase adjustment, which worsens the echo response.
Innovation Solution
A transceiver circuit with an echo-cancellation circuit comprising a steady circuit, a transient circuit, and an output circuit, where the transient circuit generates an echo response adjustment signal to correct the transient echo response, using analog-to-digital conversion and least mean square algorithms to update tap coefficients for accurate echo cancellation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the phase adjustment amount of the clock signal is increased to reduce the complexity of the phase selector, then the device complexity is reduced, but the transient echo response becomes worse
Solution Approach 1:
The echo cancellation is divided into two independent parts: steady echo cancellation and transient echo cancellation. The transient circuit generates an echo response adjustment signal specifically for transient conditions, while the steady circuit handles steady-state echo cancellation. This segmentation allows each circuit to be optimized independently, resolving the contradiction between phase adjustment amount and transient echo response.
Solution Approach 2:
The transient circuit generates the echo response adjustment signal in advance based on detected phase changes of the clock signal. By preparing the adjustment signal before the transient echo fully develops, the system can proactively cancel the transient echo rather than reactively correcting it, thereby reducing transient echo response without requiring excessive phase adjustment amounts.
2Reliability
If the phase of the clock signal is changed to lock the frequency in the slave device, then the frequency locking is achieved, but the transient echo response is generated
Solution Approach 1:
The transient circuit continuously monitors the phase of the clock signal and detects phase changes. When a phase change is detected (indicating frequency locking action), the transient circuit generates an echo response adjustment signal to cancel the resulting transient echo. This feedback mechanism allows frequency locking to proceed while simultaneously compensating for the harmful transient echo response.
Solution Approach 2:
The transient circuit acts as an intermediary between the frequency locking process and the echo cancellation process. It receives the clock signal, detects phase changes, generates the echo response adjustment signal, and feeds it to the output circuit. This intermediary function allows frequency locking to occur while the transient circuit mediates the transient echo response generation.
Data Source
AI summary
A transceiver circuit includes an ADC and an echo-cancellation circuit, wherein the echo-cancellation circuit includes a steady circuit, a transient circuit and an output circuit. In the operations of the transceiver circuit, the ADC is configured to perform an analog-to-digital conversion operation on an analog input signal to generate a digital input signal. The steady circuit is configured to generate a steady echo response according to a transmitting signal. The transient circuit is configured to generate an echo response adjustment signal according to a phase change of a clock signal used by the transmitting signal. The output circuit is configured to generate an output signal according to the digital input signal, the steady echo response, and the echo response adjustment signal.