An amplifier includes two input terminals to receive a differential, two-tone transmission signal; two output terminals; a coil having terminals connected with the input terminals respectively, and a center tap; a first transistor having the gate connected with one terminal of the coil, and the output terminal connected with one output terminal; a second transistor having the gate connected with the other terminal of the coil, and the output terminal connected with the other output terminal; a diode having a terminal connected with the center tap; and a bias circuit connected with the other terminal of the diode to output a gate voltage to turn on the first and second transistors. The diode adjusts the terminal voltage depending on a signal level of a double harmonic wave of the transmission signal supplied to the terminal of the diode from the center tap.

A logarithmic detector amplifying (LDA) system is provided for use as a high sensitivity receive booster or replacement for a low noise amplifier in a receive chain of a communication device. The LDA system includes an amplifying circuit configured to receive an input signal having a first frequency and generate an oscillation based on the input signal, a sampling circuit coupled to the amplifying circuit and configured to terminate the oscillation based on a predetermined threshold to periodically clamp and restart the oscillation to generate a series of pulses modulated by the oscillation and by the input signal, and one or more resonant circuits coupled with the amplifying circuit and configured to establish a frequency of operation and to generate an output signal having a second frequency, the second frequency being substantially the same as the first frequency.

The present disclosure relates to an amplifier configured to amplify signals within a given operational frequency, and further relates to an amplifier system, and to a Doherty amplifier. Examples include one or more resonance networks connected to an input terminal of a transistor of the amplifier that each include a first inductor arranged in between the input terminal and an intermediate node, a first capacitor arranged in between the intermediate node and ground, and a series network arranged in between the intermediate node and ground that includes a second inductor and a second capacitor. A susceptance presented by the one or more resonance networks at the input terminal cancels the input susceptance of the transistor at a frequency within an operational frequency band. In addition, an RF short is presented by each resonance network at a second harmonic of which the corresponding fundamental lies within the operational frequency band.

An apparatus for reducing lag includes a substrate; a group III-Nitride barrier layer; a source electrically coupled to the group III-Nitride barrier layer; a gate on the group III-Nitride barrier layer; a drain electrically coupled to the group III-Nitride barrier layer; a p-region being arranged at or below the group III-Nitride barrier layer; and a gate control circuit configured to control a gate voltage of the gate. Additionally, at least a portion of the p-region is arranged vertically below at least one of the following: the source, the gate, and an area between the gate and the drain.

A radio frequency amplifier includes: a transistor; an input line; an output line; and a shunt circuit that is connected between ground and the input line or the output line, wherein the shunt circuit includes: a first series resonant circuit that includes an inductor and a capacitor that are connected in series and has first resonant frequency f1; a second series resonant circuit that includes an inductor and a capacitor that are connected in series and has second resonant frequency f2 that is different from the first resonant frequency; and a resistor that is connected between a first connection point and a second connection point, the first connection point being a connection location between the inductor and the capacitor in the first series resonant circuit, the second connection point being a connection location between the inductor and the capacitor in the second series resonant circuit.

A Doherty amplifier includes: a carrier amplifier to amplify a first high frequency signal having a first higher harmonic and a second higher harmonic; a peak amplifier to amplify a second high frequency signal having the first higher harmonic and the second higher harmonic; a first series resonant circuit connected between an output end of the carrier amplifier and a ground, and configured to resonate at the frequency of the first higher harmonic; a second series resonant circuit connected between an output end of the peak amplifier and the ground, and configured to resonate at the frequency of the first higher harmonic; a first parallel resonant circuit configured to resonate at the frequency of the second higher harmonic; and a second parallel resonant circuit configured to resonate at the frequency of the second higher harmonic.