In described examples, an amplifier can be arranged to generate a first stage output signal in response to an input signal. The input signal can be coupled to control a first current coupled from a first current source through a common node to generate the first stage output signal. A replica circuit can be arranged to generate a replica load signal in response to the input signal and in response to current received from the common node. A current switch can be arranged to selectively couple a second current from a second current source to the common node in response to the replica load signal.

In some implementations, there is provided an apparatus comprising a resonant amplifier circuit including a first inductor having a first inductive input and a first inductive output; a second inductor having a second inductive input and a second inductive output; a first switch coupled to the first inductive output; and a second switch coupled to the second inductive output, wherein the first switch and the second switched are driven out of phase, wherein the first inductor is configured to be resonant with a first capacitance associated with the first switch, and wherein the second inductor is configured to be resonant with a second capacitance associated with the second switch. Related systems and articles of manufacture are also provided.

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.

Provided is an analog front-end circuit for a bioelectric sensor, which includes two feedforward amplifiers and respective feedback networks, an output common-mode voltage detector, an error amplifier, a leakage current compensator and resistance voltage dividers. Common-mode components of various types of leakage currents can be effectively suppressed.

Embodiments of the present disclosure include a harmonic power amplifying circuit with high efficiency and high bandwidth and a radio-frequency power amplifier. The circuit comprises an input matching network (11), a transistor (M), and an output matching network (12); a gate of the transistor (M) connected to an output end of the input matching network (11), a drain thereof connected to an input end of the output matching network (12), and a source thereof being grounded; wherein the output matching network (12) enables a lower sideband of the harmonic power amplifying circuit to work in a continuous inverse F amplification mode and an upper sideband of the harmonic power amplifying circuit to work in a continuous F amplification mode; wherein the output matching network (12) and a parasitic network of the transistor (M) form a low pass filter. By transitioning from the continuous inverse F power amplifier working mode to the continuous F power amplifier working mode, the efficiency of a continuous harmonic control power amplifier is effectively improved to be higher than 60%, a relative bandwidth is improved to be higher than 80%, and the harmonic impedance is simple to match and easy to realize.

An amplifier includes an input matching network; at least one transistor; an input lead coupled to the at least one transistor; a ground terminal coupled to the transistor; an output lead coupled to the at least one transistor; an output matching circuit coupled to the output lead and to the at least one transistor; and a baseband impedance enhancement circuit having at least one reactive element coupled to the input matching network. The baseband impedance enhancement circuit is configured to reduce resonances of a baseband termination.

A push-pull radio frequency power amplifier includes a coupling feedback circuit, a drive stage circuit and a power output stage circuit, in which the coupling feedback circuit is connected with the drive stage circuit and/or the power output stage circuit; the coupling feedback circuit is configured to generate an alternating voltage at an input end of a first transistor and/or an input end of a push-pull transistor; when the alternating voltage and a voltage at the input end are in a same direction, a positive feedback of an input signal at the input end is achieved; and the first transistor represents a transistor in the drive stage circuit and the push-pull transistor represents a second transistor and a third transistor that form a push-pull structure in the power output stage circuit.

An amplifier includes a first input transistor, a second input transistor, a first cascode transistor, a second cascode transistor, a first current mirror circuit, and a second current mirror circuit. The first input transistor is coupled to a first input terminal. The second input transistor is coupled to a second input terminal and the first input transistor. The first cascode transistor is coupled to the first input transistor. The second cascode transistor is coupled to the second input transistor and the first cascode transistor. The first current mirror circuit is coupled to the first cascode transistor, the second cascode transistor, and the first input terminal. The second current mirror circuit is coupled to the first cascode transistor, the second cascode transistor, and the second input terminal.

A wideband envelope modulator comprises a direct current (DC)-to-DC switching converter connected in series with a linear amplitude modulator (LAM). The DC-DC switching converter includes a pulse-width modulator that generates a PWM signal with modulated pulse widths representing a time varying magnitude of an input envelope signal or a pulse-density modulator that generates a PDM signal with a modulated pulse density representing the time varying magnitude of the input envelope signal, a field-effect transistor (FET) driver stage that generates a differential PWM or PDM drive signal, a high-power output switching stage that is driven by the PWM or PDM drive signal, and an output energy storage network including a low-pass filter (LPF) of order greater than two that filters a switching voltage produced at an output switching node of the high-power output switching stage.

Disclosed herein are signal amplifiers having a plurality of amplifier cores. Individual amplifier cores can be designed to enhance particular advantages while reducing other disadvantages. The signal amplifier can then switch between amplifier cores in a particular gain mode to achieve desired performance characteristics (e.g., improving noise figure or linearity). Examples of signal amplifiers disclosed herein include amplifier architectures with a low noise figure amplifier core that reduces the noise figure and a linearity boost amplifier core that increases linearity. The disclosed signal amplifiers can switch between a first active core and a second active core for a single or particular gain mode to achieve desired signal characteristics during different time periods.