A circuit and method for an audio op-amp that is configured to minimize crossover distortion between push and pull components of the audio op-amp. The audio op-amp includes an input stage that receives differential input signals and generates an output that amplifies the difference between the input signals. The audio op-amp further includes an output stage that receive the amplified signal and generate an audio output signal for playback by a speaker system. The output stage includes a diamond driver circuit that buffers the input stage from the speaker system, a boost circuit that includes a pair of boosting transistors that amplify the current of the amplified signal, and a biasing circuit that provides bias currents to the transistors of the boost circuit in a manner that minimizes crossover distortion between the boosting transistors.

A circuit and method for an audio op-amp that is configured to minimize crossover distortion between push and pull components of the audio op-amp. The audio op-amp includes an input stage that receives differential input signals and generates an output that amplifies the difference between the input signals. The audio op-amp further includes an output stage that receive the amplified signal and generate an audio output signal for playback by a speaker system. The output stage includes a diamond driver circuit that buffers the input stage from the speaker system, a boost circuit that includes a pair of boosting transistors that amplify the current of the amplified signal, and a biasing circuit that provides bias currents to the transistors of the boost circuit in a manner that minimizes crossover distortion between the boosting transistors.

Embodiments provide an amplification circuit, an apparatus for amplifying, a low noise amplifier, a radio receiver, a mobile terminal, a base station, and a method for amplifying. An amplification circuit (10) for amplifying a radio signal comprises a first amplification stage (12) configured to amplify an input signal, V.sub.in(t), to obtain an intermediate signal. The amplification circuit (10) further comprises a cascoding circuit (14) configured to amplify the intermediate signal to obtain a first output signal V.sub.outn(t). The amplification circuit (10) further comprises a second amplification stage (16) configured to amplify the intermediate signal to obtain a second output signal, V.sub.outp(t).

Certain aspects of the present disclosure generally relate to using cross-coupled transistors for source degeneration of an amplification stage. For example, the amplification stage generally includes a differential amplifier comprising transistors, cross-coupled transistors coupled to the differential amplifier, and an impedance coupled between drains of the cross-coupled transistors. In certain aspects, the differential amplifier comprises a push-pull amplifier, and the transistors of the push-pull amplifier comprise cascode-connected transistors.

A radio frequency module includes: a module board that includes a first principal surface and a second principal surface on opposite sides of the module board; a power amplifier configured to amplify a transmission signal; a first circuit component; and a power amplifier (PA) control circuit configured to control the power amplifier. The power amplifier and the PA control circuit are stacked on the first principal surface, and the first circuit component is disposed on the second principal surface.

A reactance cancelling radio frequency (RF) circuit array is disclosed. The reactance cancelling RF circuit array includes multiple RF circuits each coupled to one or two adjacent RF circuits by one or two pairs of coupling mediums each having a respective length less than one-quarter wavelength. In one aspect, an RF input signal is first split across the RF circuits and then combined to form an RF output signal. As a result, each RF circuit requires a lower power handling capability to process a portion of the RF input signal. In another aspect, each pair of the coupling mediums can cause reactance cancellation in each reactance-cancelling pair of the RF circuits. By coupling the RF circuits via the coupling mediums and enabling splitting-combining among the RF circuits, it is possible to miniaturize the reactance cancelling RF circuit array for improved performance across a wide frequency spectrum.

Various implementations include a common mode voltage controller for a self-boosting push pull amplifier. In some implementations, input signal are processed by: calculating, based upon the input signal, a maximum duty cycle to achieve a target differential in an output of the self-boosting push pull amplifier; calculating, based on the input signal, a set of control parameters associated with adjusting a common mode voltage of the output; and generating, based on the input signal, a pair of signals configured to adjust the common mode voltage of the output, wherein the pair of signals include a gain adjustment and offset based on the maximum duty cycle and the set of control parameters, and wherein the pair of signals are configured to maintain the target differential in the output of the self-boosting push pull amplifier as the common mode voltage is adjusted to a different operating point.

The present invention generally relates to a structure and method of audio amplifier by dynamic impedance adjustment, including a power amplifying unit, a loud-speaker, a current sensing unit and a subtraction unit. The power amplifying unit has a fixed closed loop gain, with an input side and an output side; the loud-speaker is electrically connected to the output side of the power amplifying unit; the current sensing unit senses the output current of the power amplifying unit, and the sensed output current is converted into a current control voltage signal; the subtraction unit inputs the audio voltage signal and the feedback current control voltage signal, and outputs the difference of the audio voltage signal minus the current control voltage signal, and inputs it to the input side of the power amplifying unit. The output sound quality of the loud-speaker is improved by dynamic impedance adjustment.

A fully differential amplifier includes: an input stage comprising a first amplification circuit and a second amplification circuit, one of which is configured to generate a push signal and the other of which is configured to generate a pull signal, each by amplifying a differential input signal; an output stage for generating a differential output signal based on the push signal and the pull signal; and a feedback circuit for providing common mode feedback to the first amplification circuit based on the differential output signal, wherein the second amplification circuit may include a passive network for setting a common mode voltage of the push signal or the pull signal.

A power amplifier module includes a first substrate and a second substrate, at least part of the second substrate being disposed in a region overlapping the first substrate. The second substrate includes a first amplifier circuit and a second amplifier circuit. The first substrate includes a first transformer including a primary winding having a first end and a second end and a secondary winding having a first end and a second end; a second transformer including a primary winding having a first end and a second end and a secondary winding having a first end and a second end; and multiple first conductors disposed in a row between the first transformer and the second transformer, each of the multiple first conductors extending from the wiring layer on a first main surface to the wiring layer on a second main surface of the substrate.