Feed-Forward Echo Cancellation Circuit for PGA Gain Mismatch
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Solution Overview
Problem
Existing echo cancellation devices in full duplex communication systems face mismatches between compensation signals and echoes in high frequency bands, leading to ineffective echo reduction, especially when the programmable gain amplifier's gain is adjusted without corresponding adjustments in the echo cancellation device.
Innovation Solution
A feed forward echo cancellation device comprising a first impedance circuit, a second impedance circuit, and an echo cancellation current generator circuit, which output currents to a node connected to a programmable gain amplifier via a gain control circuit, allowing for dynamic adjustment of echo cancellation currents to match the transmission current and compensate for energy mismatches.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the programmable gain amplifier adjusts its gain according to the operating state, then the amplification performance is optimized, but the echo cancellation device cannot adjust accordingly, causing mismatch between compensation signal and echo
Solution Approach 1:
The patent applies dynamics by making the echo cancellation device's impedance circuits adjustable in response to gain changes. The first and second impedance circuits are configured to output currents that dynamically adapt when the programmable gain amplifier's gain is adjusted, ensuring the compensation signal remains matched to the echo across different operating states. This resolves the contradiction by enabling both optimized amplification and maintained echo cancellation effectiveness.
2Device complexity
If a simple echo cancellation device is used, then the device complexity is reduced, but mismatch exists in high frequency bands, making echo reduction ineffective
Solution Approach 1:
The patent applies local quality by introducing a second impedance circuit specifically targeted at high frequency bands. The first impedance circuit handles general echo cancellation, while the second impedance circuit provides specialized compensation for high frequency mismatches. This localized enhancement improves high frequency echo cancellation effectiveness without requiring a complete redesign of the entire system, thus maintaining reasonable device complexity.
Data Source
AI summary
A feed forward echo cancellation device includes a first impedance circuit, a second impedance circuit, and an echo cancellation current generator circuit. The first impedance circuit is configured to output a first current to a node in response to a transmission current. The second impedance circuit is configured to output a second current to a node in response to the transmission current. The echo cancellation current generator circuit is configured to drain an echo cancellation current from the node. The node is connected to an input terminal of a programmable gain amplifier circuit via a gain control circuit, and the gain control circuit is configured to set a gain of the programmable gain amplifier circuit.