A power amplifier includes: a plurality of amplifiers; a tournament circuit including a plurality of transmission lines arranged in a tournament form and connected to the plurality of amplifiers; and a plurality of difference frequency short circuits each including an inductor and a capacitor connected in series to each other, wherein resonant frequencies of the plurality of difference frequency short circuits become smaller as the difference frequency short circuits are farther from the plurality of amplifiers, and difference frequency short circuits connected to a plurality of nodes in a stage closest to the amplifiers of the tournament circuit among the plurality of difference frequency short circuits include inductive reactance that resonates with impedance seen from the nodes toward the amplifiers at an operating frequency and have different resonant frequencies.

A transimpedance amplifier includes a T-coil in its feedback loop to expand its bandwidth. The transimpedance amplifier includes an amplifier that converts and amplifies an input current signal to an intermediary voltage signal. One terminal of the T-coil is coupled to a resistor in the feedback loop which is coupled to the input of the amplifier. Another terminal of the T-coil is coupled to the output of an amplifier. The bridge point of the T-coil is coupled to the output terminal of the transimpedance amplifier which outputs an output voltage. The T-coil includes two inductors that are mutually coupled such that a current is induced to compensate for the leakage current caused by the parasitic capacitance of the transimpedance amplifier.

A test and measurement device including a source configured to output a source signal, a source output configured to output the source signal to a connected cable, a guard drive circuit electrically coupled to the source and configured to receive the source signal and generated a guard drive signal, the guard drive circuit having a gain less than one, and a guard drive circuit output configured to output the guard drive signal to a connected guard.

Disclosed are a Doherty power amplifier (2), a controlling method and a device. In the Doherty power amplifier (2), the even order harmonic components can be fed to the drain of the amplifier to realize even order harmonic modulation. The even order harmonic components have higher power level than the odd order harmonic components, therefore, higher efficiency could be achieved.

Embodiments of RF amplifiers and RF amplifier devices include a transistor, a multiple-section bandpass filter circuit, and a harmonic termination circuit. The bandpass filter circuit includes a first connection node coupled to the amplifier input, a first inductive element coupled between the first connection node and a ground reference node, a first capacitance coupled between the first connection node and a second connection node, a second capacitance coupled between the second connection node and the ground reference node, and a second inductive element coupled between the second connection node and the transistor input. The harmonic termination circuit includes a third inductive element and a third capacitance connected in series between the transistor input and the ground reference node. The harmonic termination circuit resonates at a harmonic frequency of a fundamental frequency of operation of the RF amplifier.

An I-V conversion module includes: a current output type sensor, a pre-integral circuit, a charge transfer auxiliary circuit, and an I-V transformation circuit including an inverting amplifier. The current output type sensor is connected to an input end of the I-V transformation circuit through the pre-integral circuit. The charge transfer auxiliary circuit connects in parallel with the inverting amplifier. When both the pre-integral circuit and the charge transfer auxiliary circuit are open circuits, the pre-integral circuit pre-integrates the induction current output by the current output type sensor to store pre-integral charges. When both pre-integral circuit and the charge transfer auxiliary circuit are closed circuits, the pre-integral charges are transferred to the I-V transformation circuit. In these embodiments, both the time for establishing the I-V conversion module and power consumption can be reduced.

A wideband variable gain amplifier (VGA) having a low phase change is disclosed. The first VGA amplifies an input signal by a current steering manner so that an amplification gain is variable. The larger a variable gain amount of the first output signal amplified by the first VGA is, the more a relative phase change amount gradually increases in either positive direction or negative direction. The second VGA further amplifies the first amplified output signal in the current steering manner so as to vary the amplification gain. As a variable gain amount of a second output signal amplified by the second VGA becomes larger, a relative phase change amount gradually increases in a direction opposite to the phase change direction of the first VGA. This opposing phase changes of the first and second VGAs are canceled against each other to provide a variable amplification gain over the wideband frequency range with a low phase change.

Embodiments of RF amplifiers and RF amplifier devices include a transistor, a multiple-section bandpass filter circuit, and a harmonic termination circuit. The bandpass filter circuit includes a first connection node coupled to the amplifier input, a first inductive element coupled between the first connection node and a ground reference node, a first capacitance coupled between the first connection node and a second connection node, a second capacitance coupled between the second connection node and the ground reference node, and a second inductive element coupled between the second connection node and the transistor input. The harmonic termination circuit includes a third inductive element and a third capacitance connected in series between the transistor input and the ground reference node. The harmonic termination circuit resonates at a harmonic frequency of a fundamental frequency of operation of the RF amplifier.

An amplifier may include a transistor and input and output matching networks. One or more harmonic trap circuits may be electrically connected to a node located between the input matching network and a gate terminal of the transistor or to a node located between the output matching network and a drain terminal of the transistor. Each harmonic trap may provide a low resistance path to ground for signal energy above a fundamental operating frequency of the amplifier, such as harmonic frequencies thereof. The output matching network may act as an impedance inverter that provides a 90 degree insertion phase between the input of the output matching network and the load. A variable length drain feeder may connect a voltage source to an output of the output matching network.

An amplifier package may include a transistor, an output impedance matching circuit and one or more radial stub harmonic traps coupled to a control terminal of the transistor or to an output terminal of the transistor. The output impedance matching circuit and the radial stub harmonic traps may be formed on a single substrate or separate substrates, which may be formed from gallium nitride. Each radial stub harmonic trap may provide a low resistance path to ground for signal energy above a fundamental operating frequency of the amplifier, such as harmonic frequencies thereof.