Transceiver Hybrid Circuit Virtual Ground Echo Cancellation
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Solution Overview
Problem
Conventional transceivers for full duplex communication systems face challenges in effectively reducing echo effects due to parasitic capacitance and require complex circuit designs with unit gain buffers, leading to increased noise, harmonic distortion, and cost.
Innovation Solution
A transceiver design that incorporates a hybrid circuit with an echo cancellation device and a gain amplifier with an OP-RC AGC, where the gain amplifier is directly connected to the hybrid circuit with a virtual ground, minimizing parasitic capacitance and eliminating the need for unit gain buffers, thereby reducing complexity and noise.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If unit gain buffers are used to drive next stages and prevent signal feedback, then the input impedance is increased and output impedance is reduced, but the circuit complexity and cost increase, and noise level and harmonic distortion are raised
Solution Approach 1:
The patent removes the unit gain buffer stage from the conventional transceiver circuit. By directly connecting the hybrid circuit output to the AFE circuit input, the design extracts and eliminates the unnecessary buffering stage that caused complexity and noise issues, while relying on the inherent impedance characteristics of the hybrid circuit and AFE circuit interfaces
Solution Approach 2:
The patent merges the hybrid circuit and AFE circuit into a directly connected integrated structure, eliminating the intermediate unit gain buffer. This consolidation reduces the number of discrete components and simplifies the overall circuit architecture while maintaining signal integrity through proper impedance matching
2Reliability
If unit gain buffers are used to drive next stages, then the impedance matching is improved, but the noise level and harmonic distortion of active elements are raised
Solution Approach 1:
The patent extracts and removes the unit gain buffer active element from the signal path. By eliminating this active component, the design removes the primary noise and harmonic distortion source, achieving cleaner signal transmission through passive direct connection with proper impedance matching
3Reliability
If conventional transceiver design is used with parasitic capacitance effect, then the echo effect cannot be effectively reduced, but the circuit design is simpler
Solution Approach 1:
The patent implements echo cancellation through feedback mechanisms within the hybrid circuit and AFE circuit. The system uses the transmitted signal information to generate cancellation signals that are fed back to subtract from the received signal, effectively reducing echo while accounting for parasitic capacitance effects in the direct-connected architecture
Data Source
AI summary
A transceiver in a full duplex communication system includes a hybrid circuit for transmitting a transmission signal or receiving a receive signal via the channel, the hybrid circuit includes an echo cancellation device for removing transmission signal components from the receive signal; wherein the hybrid circuit outputs a processed receive signal; and a gain amplifier being an OP-RC AGC is directly connected to the hybrid circuit for amplifying the processed receive signal, wherein a first node of the gain amplifier coupled to the echo cancellation device is a virtual ground.