A method for processing audio signals is provided comprising outputting an audio signal; receiving the output audio signal via a first receiving path as a first received audio signal; receiving the output audio signal via a second receiving path as a second received audio signal; determining an echo suppression gain based on the first received audio signal and the second received audio signal; and filtering echo suppression of the audio signal based on the first received audio signal and the echo suppression gain.

A method for processing audio signals is provided comprising outputting an audio signal; receiving the output audio signal via a first receiving path as a first received audio signal; receiving the output audio signal via a second receiving path as a second received audio signal; determining an echo suppression gain based on the first received audio signal and the second received audio signal; and filtering echo suppression of the audio signal based on the first received audio signal and the echo suppression gain.

A circuit is provided for ringing suppression. The circuit comprises a termination resistor coupled to a bus via a switch; and a control circuit. The control circuit comprises an input coupled to a data input pin of a bus transceiver and an output coupled to control the termination resistor. The circuit is configured to selectively couple the resistor to the bus in response to a transition on the input bit stream.

A circuit is provided for ringing suppression. The circuit comprises a termination resistor coupled to a bus via a switch; and a control circuit. The control circuit comprises an input coupled to a data input pin of a bus transceiver and an output coupled to control the termination resistor. The circuit is configured to selectively couple the resistor to the bus in response to a transition on the input bit stream.

An echo is allowed to be effectively removed while a processing load on an arithmetic device is reduced. When a magnitude of a reference signal transmitted to a speaker is equal to or greater than a first threshold, a learning algorithm using nonlinear processing is selected. When the magnitude of the reference signal is smaller than the first threshold, a learning algorithm using linear processing is selected. The echo is learnt using the selected learning algorithm to remove an echo included in an input signal picked up by a microphone based on a learning result.

An echo is allowed to be effectively removed while a processing load on an arithmetic device is reduced. When a magnitude of a reference signal transmitted to a speaker is equal to or greater than a first threshold, a learning algorithm using nonlinear processing is selected. When the magnitude of the reference signal is smaller than the first threshold, a learning algorithm using linear processing is selected. The echo is learnt using the selected learning algorithm to remove an echo included in an input signal picked up by a microphone based on a learning result.

Apparatus and methods for phase shifting are provided herein. In certain embodiments, a phase shifter includes a first port, a first controllable reflective load, a second port, a second controllable reflective load, and a pair of coupled lines that are electromagnetically coupled to one another. The pair of coupled lines includes a first conductive line between the first port and the first controllable reflective load and a second conductive line between the second controllable reflective load and the second port. At least one of the first controllable reflective load or the second controllable reflective load includes a switched transmission line load.

Apparatus and methods for phase shifting are provided herein. In certain embodiments, a phase shifter includes a first port, a first controllable reflective load, a second port, a second controllable reflective load, and a pair of coupled lines that are electromagnetically coupled to one another. The pair of coupled lines includes a first conductive line between the first port and the first controllable reflective load and a second conductive line between the second controllable reflective load and the second port. At least one of the first controllable reflective load or the second controllable reflective load includes a switched transmission line load.

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.

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.