An amplification subsystem for a communication system includes a downstream amplifier configured to transmit a downstream signal within a first frequency range, an upstream amplifier configured to transmit an upstream signal within a second frequency range, and a bidirectional amplifier configured to selectively transmit a mid-band signal in either of the upstream and downstream direction.

An amplification subsystem for a communication system includes a downstream amplifier configured to transmit a downstream signal within a first frequency range, an upstream amplifier configured to transmit an upstream signal within a second frequency range, and a bidirectional amplifier configured to selectively transmit a mid-band signal in either of the upstream and downstream direction.

Disclosed is a bidirectional amplifier. The bidirectional amplifier includes a first matching circuit, a second matching circuit, an amplifier circuit connected between the first matching circuit and the second matching circuit, that amplifies a first input signal received from the first matching circuit to output the amplified first input signal to the second matching circuit, and that amplifies a second input signal received from the second matching circuit to output the amplified first input signal to the first matching circuit, and the first and second matching circuits have a symmetrical structure and operate complementary to each other.

Disclosed is a bidirectional amplifier. The bidirectional amplifier includes a first matching circuit, a second matching circuit, an amplifier circuit connected between the first matching circuit and the second matching circuit, that amplifies a first input signal received from the first matching circuit to output the amplified first input signal to the second matching circuit, and that amplifies a second input signal received from the second matching circuit to output the amplified first input signal to the first matching circuit, and the first and second matching circuits have a symmetrical structure and operate complementary to each other.

A bidirectional RF circuit, preferably including a plurality of terminals, a switch, a transistor, a coupler, and a feedback network. The circuit can optionally include a drain matching network, an input matching network, and/or one or more tuning inputs. In some variations, the circuit can optionally include one or more impedance networks, such as an impedance network used in place of the feedback network; in some such variations, the circuit may not include a coupler, switch, and/or input matching network. A method for circuit operation, preferably including operating in an amplifier mode, operating in a rectifier mode, and/or transitioning between operation modes.

An amplifier circuit according to the present invention includes a first block, a second block, a transformer, and a reference node and operates as a negative impedance converter circuit. A circuit configuration formed by a first transistor and at least one first passive component in the first block with respect to a first terminal of the transformer and a circuit configuration formed by a second transistor and at least one second passive component in the second block with respect to a second terminal of the transformer are the same as each other.

Provided is a bidirectional amplifier that can be downsized even when performance varies for each of a plurality of amplifying units. The bidirectional amplifier includes: a first amplifying unit configured to amplify a first signal input from a first terminal and output the amplified first signal from a second terminal; a second amplifying unit configured to amplify a second signal input from the second terminal, output the amplified second signal from the first terminal, and including a compensation element and a compensation element compensating for degradation in performance of the first amplifying unit; and a control unit configured to control an operation of the first amplifying unit and an operation of the second amplifying unit.

Provided is a bidirectional amplifier that can be downsized even when performance varies for each of a plurality of amplifying units. The bidirectional amplifier includes: a first amplifying unit configured to amplify a first signal input from a first terminal and output the amplified first signal from a second terminal; a second amplifying unit configured to amplify a second signal input from the second terminal, output the amplified second signal from the first terminal, and including a compensation element and a compensation element compensating for degradation in performance of the first amplifying unit; and a control unit configured to control an operation of the first amplifying unit and an operation of the second amplifying unit.

A network interface device includes a passive path between an entry port and a first port. The network interface device also includes an active path between the entry port and a second port. The network interface device also includes a buffer in the active path configured to absorb, attenuate, terminate, or isolate radio-frequency (RF) signals. The network interface device also includes a switching element in the active path configured to cause the RF signals to bypass the buffer when the network interface is in a first state that exists during powered operation of the network interface device, and direct the RF signals to the buffer when the network interface device is in a second state that exists during non-powered operation or faulted operation of the network interface device.

A network interface device includes a passive path between an entry port and a first port. The network interface device also includes an active path between the entry port and a second port. The network interface device also includes a buffer in the active path configured to absorb, attenuate, terminate, or isolate radio-frequency (RF) signals. The network interface device also includes a switching element in the active path configured to cause the RF signals to bypass the buffer when the network interface is in a first state that exists during powered operation of the network interface device, and direct the RF signals to the buffer when the network interface device is in a second state that exists during non-powered operation or faulted operation of the network interface device.