A linear low noise amplifier is disclosed. In at least one exemplary embodiment, the linear low noise amplifier may include a first metal oxide semiconductor field effect transistor (MOSFET) configured to operate in a triode mode coupled to a second MOSFET configured to operate in a saturation mode. Linearity of the low noise amplifier may be determined, at least in part, by a transconductance associated with the second MOSFET and a channel resistance associated the first MOSFET.

The present disclosure relates to an amplifier circuit comprising a main amplifier circuit comprising a plurality of first switched-capacitor, SC, house-of-cards, HoC, amplifier cells coupled in parallel between an input and an output of the main amplifier circuit, at least one peak amplifier circuit comprising a plurality of second SC HoC amplifier cells coupled in parallel between an input and an output of the peak amplifier circuit, wherein the output of the main amplifier circuit and the output of the peak amplifier circuit are coupled to a common load.

An input signal amplification system comprises at least two different means of amplifying input signals in order to obtain amplified signals. It also comprises at least one means of summing amplified signals, and dynamic means of activating or deactivating one or more of the amplifying means based on input signals.

The present invention provides a control circuit to stabilize an output power of a power amplifier. The control circuit comprises a voltage clamping loop, a current clamping loop and a loop for reducing power variation under VSWR, where the voltage clamping loop is used to clamp an output voltage of the power amplifier within a defined voltage range, the current clamping loop is used to clamp a current of the power amplifier within a defined current range, and the loop for reducing power variation under VSWR is implemented by an impedance detector to compensate the output power under VSWR variation.

A power amplifier includes a class D amplification section and a load current feedback circuit. The class D amplification section includes an input section and a switching section serving as an output stage and switched depending on a signal input to the input section, and outputs current from a power source to a load via the switching section. The load current feedback circuit negatively feeds back the current flowing in the load to the input section of the class D amplification section.

Embodiments of RF amplifiers and packaged RF amplifier devices each include a transistor, an impedance matching circuit, and a video bandwidth circuit. The impedance matching circuit is coupled between the transistor and an RF I/O (e.g., an input or output lead). The video bandwidth circuit is coupled between a connection node of the impedance matching circuit and a ground reference node. The video bandwidth circuit includes a plurality of components, which includes an envelope inductor and an envelope capacitor coupled in series between the connection node and the ground reference node. The video bandwidth circuit further includes a first bypass capacitor coupled in parallel across one or more of the plurality of components of the video bandwidth circuit.

Mobile devices such as mobile phones include amplifiers for example audio and RF amplifiers which may consume a significant amount of the available power supplied by a battery. An amplifying system 100 for a mobile device is described the amplifying system comprising a current monitor 12 arranged between a first supply node and a second supply node and operable to monitor a current flow between the first and second supply nodes and to output a monitored current value; a peak current limiter 14 configured to limit an amplifier current to an amplifier to not exceed a maximum peak current value and coupled to a one of the first supply node and the second supply node; a controller coupled to the current monitor output and configured to control the peak current limiter. The amplifying system can dynamically manage the peak current available to the amplifier dependent on the load current being supplied by a battery.

An apparatus includes: first and second transistors, each of the first and second transistors includes a gate terminal, a source terminal, and a drain terminal; and a transformer including a primary winding and first and second secondary windings, the primary winding is coupled to a first input node configured to receive an input signal and a second input node configured to receive a potential, the first and second secondary windings are coupled to gate terminals of the first and second transistors and cross-coupled to source terminals of the first and second transistors.

In at least one embodiment, the invention provides a bidirectional amplifier and method of control that enables immediate feedback directly from the output for fast response and low distortion. Mechanisms responsive to instantaneous feedback eliminate undershoot, overshoot, and sub-harmonic behavior. One embodiment comprises two switches and a single two-terminal inductor. Another embodiment produces a bipolar output from a single unregulated supply rail. The use of Predictive Energy Balancing controls yield high efficiency and low total harmonic distortion. These amplifiers are suited for audio application, and can drive piezo or dynamic speakers.

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.