Echo Cancellation via Variable Capacitor Calibration
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Solution Overview
Problem
In full-duplex Ethernet communication systems, echo interference significantly affects signal reception due to impedance mismatches, leading to noise interference, which existing technologies have not effectively addressed.
Innovation Solution
A communication device with a digital echo canceller, hybrid fine-tune circuit, and analog echo cancellation circuit that uses variable capacitors to generate capacitance calibration signals, optimizing capacitance settings to minimize echo interference by estimating echo energy and adjusting capacitors to reduce echo signal interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If full-duplex data transmission is implemented, then transmission speed and communication efficiency are improved, but echo interference and signal quality deteriorate
Solution Approach 1:
The patent applies echo cancellation technology that converts the harmful echo interference into a beneficial signal processing function. By using adaptive filters to model and subtract the echo path, the system transforms the problematic reflected signals into cancelable components, allowing full-duplex operation to proceed without degradation from echo noise
Solution Approach 2:
The patent introduces hybrid circuits as intermediary components between the transmitter and receiver. These hybrid circuits act as mediators that separate the transmit and receive signal paths, preventing direct coupling and reducing echo feedback. The hybrid circuit serves as a buffer that isolates the two directions of signal flow while maintaining full-duplex capability
2Object-affected harmful factors
If impedance matching is improved, then echo interference is reduced, but device complexity increases
Solution Approach 1:
The patent employs dynamic impedance matching through variable capacitors that can adjust their capacitance values in real-time. Instead of fixed impedance matching components, the system uses controllable capacitive elements that adapt to changing transmission conditions, allowing optimal echo cancellation across different operating states without requiring complex multi-component circuits
Solution Approach 2:
The patent changes the electrical parameters of the circuit by using variable capacitors with adjustable capacitance values. By modifying the capacitive parameters dynamically, the system achieves adaptive impedance matching that reduces echo interference without adding complex circuit topologies. The parameter adjustment is controlled through digital signals that modify the physical electrical characteristics of the matching network
Data Source
AI summary
A communication device and an echo cancellation method are provided. A digital echo canceller is coupled to a transmitting circuit and a receiving circuit to generate an echo energy indicator according to a digital output signal and a digital input signal. A transceiving front-end circuit receives the analog output signal and generates a hybrid interface signal. A hybrid fine-tune circuit generates a first and a second capacitance calibration signals according to the echo energy indicator. An analog echo cancellation circuit receives the first and second capacitance calibration signals, and includes a first and a second variable capacitors controlled by the first capacitance calibration signal and a third and a fourth variable capacitors controlled by the second capacitance calibration signal. The analog echo cancellation circuit receives the analog output signal and the hybrid interface signal, and generates the analog input signal according to the first and second capacitance calibration signals.