# US 12,119,851 B2 · Feed forward echo cancellation device and echo cancellation method > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 12,119,851 B2 - Document ID: US12119851B2 - Status: Granted - Kind: B2 - Application number: 17/861,378 - Filed: 2022-07-11 - Published: 2023-04-13 - Granted: 2024-10-15 - Earliest claimed: 2021-10-07 - Assignees: Realtek Semiconductor Corp. - Applicants: Realtek Semiconductor Corporation - Inventors: Chien-Wen Chen; Yi-Ching Liao - Web page: https://patentgrep.com/patent/US12119851B2 ## CPC - H04B 1/0475: {with means for limiting noise, interference or distortion (H04B1/0483 takes precedence)} - H03G 3/3036: {in high-frequency amplifiers or in frequency-changers (H03G3/3052, H03G3/32, H03G3/34 take precedence)} - H03G 2201/103: being an amplifying element - H04B 2001/0416: {having gain or transmission power control} - H04B: TRANSMISSION - H03G: CONTROL OF AMPLIFICATION ## Abstract 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. ## Claims ### Claim 1 A feed forward echo cancellation device, comprising: a first impedance circuit configured to output a first current to a node in response to a transmission current; a second impedance circuit configured to output a second current to the node in response to the transmission current; and an echo cancellation current generator circuit configured to drain an echo cancellation current from the node, wherein the node is connected to an input terminal of a programmable gain amplifier circuit via a gain control circuit, the gain control circuit is configured to set a gain of the programmable gain amplifier circuit, and a bandwidth of the second impedance circuit is controlled based on an output of the programmable gain amplifier circuit. ### Claim 2 (depends on 1) The feed forward echo cancellation device of claim 1, wherein the first current, the second current, and the echo cancellation current are canceled with each other at the node. ### Claim 3 (depends on 1) The feed forward echo cancellation device of claim 1, wherein a summation of the first current and the second current is equal to the echo cancellation current. ### Claim 4 (depends on 1) The feed forward echo cancellation device of claim 1, wherein the first impedance circuit, the second impedance circuit, and the echo cancellation current generator circuit-are directly coupled to the node. ### Claim 5 (depends on 1) The feed forward echo cancellation device of claim 1, wherein the gain control circuit is an AC coupling circuit or a DC coupling circuit. ### Claim 6 (depends on 1) The feed forward echo cancellation device of claim 1, wherein the second impedance circuit comprises a resistor and a capacitor, and the resistor and the capacitor are configured to set a corner frequency of the second current. ### Claim 7 (depends on 1) The feed forward echo cancellation device of claim 1, wherein the echo cancellation current generator circuit is a current digital to analog converter circuit. ### Claim 8 (depends on 1) The feed forward echo cancellation device of claim 1, wherein the gain control circuit is adjusted based on a system convergence indicator, in order to set the gain or a ratio of the transmission current. ### Claim 9 (depends on 1) The feed forward echo cancellation device of claim 1, wherein the node is further configured to receive a data signal, and transmit the data signal to the programable gain amplifier circuit. ### Claim 10 (depends on 1) The feed forward echo cancellation device of claim 1, wherein a transmitter of a near end communication device transmits a signal to a far end communication device via a path according to the transmission current, and the first impedance circuit is configured to provide an impedance having a resistance value corresponding to an impedance of the path. ### Claim 11 An echo cancellation method, comprising: outputting a first current to a node in response to a transmission current, wherein 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; draining an echo cancellation current from the node; and outputting a second current to the node in response to the transmission current, wherein a summation of the first current and the second current is approximate to the echo cancellation current, wherein the second current is outputted from a second impedance circuit, and a bandwidth of the second impedance circuit is controlled based on an output of the programmable gain amplifier circuit. ### Claim 12 (depends on 11) The echo cancellation method of claim 11, wherein the first current, the second current, and the echo cancellation current are canceled with each other at the node. ### Claim 13 (depends on 11) The echo cancellation method of claim 11, wherein a summation of the first current and the second current is equal to the echo cancellation current. ### Claim 14 (depends on 11) The echo cancellation method of claim 11, wherein the first current, the second current, and the echo cancellation current are directly transmitted to the node. ### Claim 15 (depends on 11) The echo cancellation method of claim 11, wherein the gain control circuit is an AC coupling circuit or a DC coupling circuit. ### Claim 16 (depends on 11) The echo cancellation method of claim 11, wherein the first current is outputted from a first impedance circuit, a transmitter of a near end communication device transmits a signal to a far end communication device via a path according to the transmission current, and the first impedance circuit is configured to provide an impedance having a resistance value corresponding to an impedance of the path.