A high frequency power amplifier includes a first high frequency amplifier, a final high frequency amplifier, and a tunable filter. The tunable filter is connected between the first high frequency amplifier and the final high frequency amplifier. The first high frequency amplifier and the final high frequency amplifier are each a multimode/multiband power amplifier. The tunable filter is regulated such that its pass band includes the frequency band of a transmission signal and its attenuation band includes the frequency band of a reception signal in a communication band used in transmission and reception. The pass band and the attenuation band are switched by the tunable filter in accordance with the communication band used in transmission and reception.

Superconducting output amplifiers with interstage filters and related methods are described. An example superconducting output amplifier includes a first superconducting output amplifier stage and a second superconducting output amplifier stage. The superconducting output amplifier may further include a first terminal for receiving a first single flux quantum (SFQ) pulse train and coupling the SFQ pulse train to each of the first superconducting output amplifier stage and the second superconducting output amplifier stage. The superconducting output amplifier may further include an interstage filter comprising a damped Josephson junction (JJ) coupled between the first superconducting output amplifier stage and the second superconducting output amplifier stage, where the interstage filter is arranged to reduce distortion in an output voltage waveform generated by the superconducting output amplifier in response to at least the first SFQ pulse train.

A high dynamic range sensing front-end for bio-signal recording systems in accordance with embodiments of the invention are disclosed. In one embodiment, a bio-signal amplifier includes an input signal, where the input signal is modulated to a predetermined chopping frequency, a first amplifier stage, a parallel-RC circuit connected to the first amplifier stage and configured to generate a parallel-RC circuit output by selectively blocking an offset current, a second amplifier stage connected to the parallel-RC circuit that includes a second input configured to receive the parallel-RC circuit output and generate a second output that is an amplified version of the input signal with ripple-rejection. Further, the bio-signal amplifier can also include an auxiliary path configured for boosting input impedance by pre-charging at least one input capacitor. In addition, the bio-signal amplifier can also include a DC-servo feedback loop that includes an integrator that utilizes a duty-cycled resistor.

A circuit includes a first transistor comprising a gate, a source, and a drain, and an inductor coupled between the gate and the source of the first transistor, wherein the source is further coupled to a current source and the gate is further coupled to an amplifier.

An amplifier circuit with in-band gain degradation compensation is shown. The amplifier circuit has an input-stage amplifier, at least one intermediate-stage amplifier, and an output-stage amplifier cascaded between an input port and an output port of the amplifier circuit. A compensation capacitor is coupled between the output port of the amplifier circuit and an output port of the input-stage amplifier. A high-order damping circuit is coupled to an output port of the intermediate-stage amplifier.

The present disclosure relates to a 5th generation (5G) or pre-5G communication system for supporting a data transmission rate higher than that of a 4th generation (4G) communication system such as long term evolution (LTE). The present disclosure is to amplify transmission signals in a wireless communication system, and a transmitting device may include an antenna array including a plurality of antenna elements, a plurality of amplification chains for amplifying signals transmitted through the plurality of the antenna elements, and a power supply line for supplying powers to the plurality of the amplification chains. Herein, the powers used by power amplifiers included in at least one amplification chain of the plurality of the amplification chains may be divided by filtering or by independent pads and branch-lines.

An output matching circuit includes: a converter electrically connected to an output end of a power amplifier element to convert an impedance of the output end to an impedance higher than the impedance of the output end by magnetic coupling; and a first filter circuit electrically connected between the output end of the power amplifier element and the converter to make a short circuit in a frequency band different from a predetermined transmission frequency band.

A filter combiner for a Doherty amplifier includes a first port with an impedance of Z0 configured to be connected to an output of a carrier amplifier; a second port with an impedance of Z0.Math.r/(1+r) configured to be connected to a load; a third port with an impedance of Z0.Math.r/(1+r) configured to be connected to a peak amplifier, wherein r is a power ratio for the carrier amplifier to the peak amplifier; and a fourth port with an impedance of Z0 configured to be connected to an output port of the Doherty amplifier. The first port is connected to the second port via a first network that is a lowpass filter and to the third port via a second network that is a lowpass filter which is configured to operate as a band stop filter upon loading the input or the output of the second network with a high impedance when the peak amplifier is off. The third port is connected to the fourth port via a third network that is a lowpass filter configured to operate as a band stop filter upon loading the input or the output of the second network with a high impedance when the peak amplifier is off. The fourth port is connected to the second port via a fourth network that is a lowpass filter.

A power amplifier circuit includes a differential amplifier circuit configured to amplify a radio-frequency signal, a transformer disposed on an output side with respect to the differential amplifier circuit and including a primary winding and a secondary winding, and a dispersion circuit coupled to a midpoint of the primary winding of the transformer and configured to operate as an adjustment circuit. The dispersion circuit is configured to adjust, based on a supply voltage controlled in accordance with the envelope of the radio-frequency signal, a bias (bias current or bias voltage) to be supplied to the differential amplifier circuit.

An amplification circuit includes: an amplifier including a transistor that is connected between an input terminal and an output terminal; an input matching network that is connected between the input terminal and an input side of the amplifier and converts an impedance from a low impedance to a high impedance; a limiter circuit that is connected between a node between the input matching network and the input side of the amplifier, and ground and includes two diodes connected in opposite directions to each other; and a capacitor that is connected in series with the limiter circuit between the node and ground.