A low noise amplifier includes at least two variable gain amplifier stages, each variable gain amplifier configured to accept an input signal and to provide a load driving signal; a tunable bandpass filter connected as a load to each variable gain amplifier stage, wherein each bandpass filter includes a resonant tank, each resonant tank including an inductor, wherein each inductor of each resonant tank is oriented in orthogonal relation with respect to each respective longitudinal axis of each next inductor, the orthogonal relation of the respective longitudinal axes configured to reduce mutual coupling between the tunable bandpass filters; a cross-coupled transistor pair, and at least one cross-coupled compensation transistor pair biased in a subthreshold region configured to add a transconductance component as a function of a load driving signal; and, a controller circuit configured to tune each tunable bandpass filter.

A radio frequency low noise amplifier circuit with a receive signal input, a receive signal output, and a voltage source include a low noise amplifier and a coupled inductor circuit with a primary inductive chain connected to the output of the low noise amplifier and to the voltage source. The coupled inductor circuit further includes a secondary inductive chain with a first inductor electromagnetically coupled to the primary inductive chain, and a second inductor in series with the first inductor and magnetically coupled to the primary inductive chain. The second inductor is connected to a feedback node of the low noise amplifier. There is an output matching network connected to the first inductor of the secondary inductive chain and to the receive signal output.

A low noise amplifier includes at least two variable gain amplifier stages, each variable gain amplifier configured to accept an input signal and to provide a load driving signal; a tunable bandpass filter connected as a load to each variable gain amplifier stage, wherein each bandpass filter includes a resonant tank, each resonant tank including an inductor, wherein each inductor of each resonant tank is oriented in orthogonal relation with respect to each respective longitudinal axis of each next inductor, the orthogonal relation of the respective longitudinal axes configured to reduce mutual coupling between the tunable bandpass filters; a cross-coupled transistor pair, and at least one cross-coupled compensation transistor pair biased in a subthreshold region configured to add a transconductance component as a function of a load driving signal; and, a controller circuit configured to tune each tunable bandpass filter.

One embodiment describes a transimpedance amplifier (TIA) system. The system includes a transistor arranged between an input node and an output node to set an amplitude of an output voltage at the output node based on an amplitude of an input current signal provided at the input node. The system also includes a negative feedback transformer coupled to the transistor to provide a negative feedback gain with respect to the output voltage to substantially increase transconductance of the transistor.

Front end systems and related devices, integrated circuits, modules, and methods are disclosed. One such front end system includes a low noise amplifier in a receive path and a multi-mode power amplifier circuit in a transmit path. The low noise amplifier includes a first inductor, an amplification circuit, and a second inductor magnetically coupled to the first inductor to provide negative feedback to linearize the low noise amplifier. The multi-mode power amplifier circuit includes a stacked output stage including a transistor stack of two or more transistors. The multi-mode power amplifier circuit also includes a bias circuit configured to control a bias of at least one transistor of the transistor stack based on a mode of the multi-mode power amplifier circuit. Other embodiments of front end systems are disclosed, along with related devices, integrated circuits, modules, methods, and components thereof.

An apparatus includes a low-noise amplifier having an input and an output, a first switch coupled between the input of the low-noise amplifier and the output of the low-noise amplifier, and a transformer including a first inductor and a second inductor, wherein the first inductor is coupled to the output of the low-noise amplifier. The apparatus also includes a power amplifier having an input and an output, and a switching circuit coupled between the output of the power amplifier and the second inductor.

An amplifier, comprising: an amplifying element having an input side and an output side; a first transformer on the output side of the amplifying element arranged to mutually couple a fraction of the output current from the amplifying element onto the input side of the amplifying element; a second transformer on the input side of the amplifying element arranged to increase the input voltage on the input side via mutual coupling of its primary and secondary windings; wherein a primary winding of the first transformer is connected to an output of the amplifying element; wherein a secondary winding of the first transformer is ac connected to a secondary winding of the second transformer; and wherein the primary winding of the first transformer is dc blocked from the secondary winding of the second transformer. The negative and the positive reactive feedback loops are not formed from the same trifilar transformer.

Compact low noise amplifiers that have wide-band coverage while meeting necessary input matching and output matching characteristics. Embodiments include a wide-band, two-stage LNA with minimum degradation in performance compared to multiple narrow-band, single-stage LNAs. A generalized embodiment includes a first amplifier stage having a terminal coupled to a mutually coupled inductor circuit and to a second amplifier stage. The second amplifier stage includes a terminal coupled to the mutually coupled inductor circuit. The mutually coupled inductor circuit comprises electromagnetically coupled inductors L1, L2. Second terminals of the first and second amplifier stages are coupled to respective degeneration inductors. The electromagnetically coupled inductors L1, L2 of the inductor circuit substantially increase the output bandwidth of the LNA with minimum degradation in performance.

A differential power amplifier is disclosed. The differential power amplifier includes an output transformer having a primary winding with a first primary terminal, a center-tap terminal, and a second primary terminal. The differential power amplifier further includes a positive amplifier having a first signal output terminal coupled to the first primary terminal and a negative amplifier having a second signal output terminal coupled to the second primary terminal. A harmonic tuning network is made up of a common-mode inductor coupled between the center-tap terminal and a tuning node and a first electronically tunable capacitor coupled between the tuning node and a fixed voltage node. A controller is configured to tune the electronically tunable capacitor to resonate with the common-mode inductor at a second harmonic frequency of a signal being amplified by the positive amplifier and the negative amplifier.

A differential power amplifier is disclosed. The differential power amplifier includes an output transformer having a primary winding with a first primary terminal, a center-tap terminal, and a second primary terminal. The differential power amplifier further includes a positive amplifier having a first signal output terminal coupled to the first primary terminal and a negative amplifier having a second signal output terminal coupled to the second primary terminal. A harmonic tuning network is made up of a common-mode inductor coupled between the center-tap terminal and a tuning node and a first electronically tunable capacitor coupled between the tuning node and a fixed voltage node. A controller is configured to tune the electronically tunable capacitor to resonate with the common-mode inductor at a second harmonic frequency of a signal being amplified by the positive amplifier and the negative amplifier.