A network interface device includes an active path between an entry port and a first input/output port. The network interface device also includes a passive path between the entry port and a second input/output 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 selectively bypass the buffer during normal operating conditions.

A bidirectional time-division duplexing transceiver circuit includes a first and a second bidirectional phase-shift circuit, and a bidirectional amplifier circuit including a first amplifier circuit and a second amplifier circuit. The first amplifier circuit and the second amplifier circuit are coupled via double-pole-double-throw (DPDT) switches to radio-frequency (RF) antennas and the first and the second bidirectional phase-shift circuits. The (DPDT) switches enable the first amplifier circuit and the second amplifier circuit to be operable simultaneously as transmit (TX) path amplifiers in a first time slot and as a receive (RX) path amplifiers in a second time slot.

In a general aspect, a current sense amplifier circuit (CSA) can include a null amplifier path and a main amplifier path that are both configured to receive a differential input voltage. The null amplifier path can output a first differential output voltage based on the differential input voltage. The main amplifier path can also be configured to receive the first differential output voltage and output a second differential output voltage based on the differential input voltage and the first differential output voltage. The null and main amplifier paths can each include a differential amplifier having first and second input stages that are each configured to receive the differential input voltage. The first input stage and the second input stage of the main amplifier path can and be powered by a respective (first and second) floating voltage supply rails that are referenced to a floating ground rail.

In a general aspect, a current sense amplifier circuit (CSA) can include a null amplifier path and a main amplifier path that are both configured to receive a differential input voltage. The null amplifier path can output a first differential output voltage based on the differential input voltage. The main amplifier path can also be configured to receive the first differential output voltage and output a second differential output voltage based on the differential input voltage and the first differential output voltage. The null and main amplifier paths can each include a differential amplifier having first and second input stages that are each configured to receive the differential input voltage. The first input stage and the second input stage of the main amplifier path can and be powered by a respective (first and second) floating voltage supply rails that are referenced to a floating ground rail.

A bidirectional amplifier includes first and second ports, with a first summing node connected to the first port and a second summing node connected to the second port. First and second gain stages are connected between the first and second summing nodes, respectively, and a first node. First and second feedback stages are also connected between the first and second summing nodes, respectively, and the first node. The amplifier operates in a first mode in which an amplified version of a signal applied to the first port is provided at the second port, or a second mode in which an amplified version of a signal applied to the second port is provided at the first port. The first and second gain stages are preferably first and second common emitter cascode arrangements, and the first and second feedback stages are preferably first and second emitter followers.

A bidirectional amplifier includes first and second ports, with a first summing node connected to the first port and a second summing node connected to the second port. First and second gain stages are connected between the first and second summing nodes, respectively, and a first node. First and second feedback stages are also connected between the first and second summing nodes, respectively, and the first node. The amplifier operates in a first mode in which an amplified version of a signal applied to the first port is provided at the second port, or a second mode in which an amplified version of a signal applied to the second port is provided at the first port. The first and second gain stages are preferably first and second common emitter cascode arrangements, and the first and second feedback stages are preferably first and second emitter followers.

A multi-way power amplifier circuit includes two baluns and a number (2N) of differential power amplifiers, where N2. Each balun generates a number (N) of corresponding differential intermediate signal pairs based on a respective to-be-amplified signal. Each differential power amplifier generates a respective differential amplified signal pair based on a respective differential intermediate signal pair. One of the baluns includes: a first transmission line and a second transmission line connected to each other; a number (N) of third transmission lines electromagnetically coupled to the first transmission line; and a number (N) of fourth transmission lines electromagnetically coupled to the second transmission line.

A multi-way power amplifier circuit includes two baluns and a number (2N) of differential power amplifiers, where N2. Each balun generates a number (N) of corresponding differential intermediate signal pairs based on a respective to-be-amplified signal. Each differential power amplifier generates a respective differential amplified signal pair based on a respective differential intermediate signal pair. One of the baluns includes: a first transmission line and a second transmission line connected to each other; a number (N) of third transmission lines electromagnetically coupled to the first transmission line; and a number (N) of fourth transmission lines electromagnetically coupled to the second transmission line.

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.

A multi-way power amplifier circuit includes two baluns and a number (2N) of differential power amplifiers, where N2. Each balun generates a number (N) of corresponding differential intermediate signal pairs based on a respective to-be-amplified signal. Each differential power amplifier generates a respective differential amplified signal pair based on a respective differential intermediate signal pair. One of the baluns includes: a first transmission line and a second transmission line connected to each other; a number (N) of third transmission lines electromagnetically coupled to the first transmission line; and a number (N) of fourth transmission lines electromagnetically coupled to the second transmission line.