According to one embodiment, a high frequency amplifier circuit includes a first transistor including a gate to which an input signal is input; a second transistor including a gate grounded, and a source coupled to a drain of the first transistor; a first switch coupled between a first output terminal and a first node located between the drain of the second transistor and an inductor; a third transistor including a gate to which the input signal is input; a fourth transistor including a gate that is grounded, and a source coupled to a drain of the third transistor; a second switch coupled between a second output terminal and a second node located between the drain of the fourth transistor and an inductor; and a third switch coupled between the first node and the second node.

Disclosed herein are signal amplifier architectures that provide a plurality of gain modes. Different gain modes can use different paths through the amplifier architecture. Switches that are used to select the path through the amplifier architecture can be configured to also provide targeted impedance in a degeneration block or matrix. The switches that select the gain path are provided in the amplifier architecture and are thus not needed or used in the degeneration block, thereby reducing the size of the package for the amplifier architecture, improving the noise figure (NF), improving impedance matching, and eliminating the need for control logic associated with the degeneration block or matrix.

An amplification circuit includes a switch circuit, an amplifier, and a control circuit. The switch circuit has a first terminal coupled to a radio frequency signal input terminal or a system voltage terminal, a second terminal coupled to an input terminal of the amplifier, and a control terminal configured to receive a control signal. The amplifier amplifies a radio frequency signal. The control circuit generates the control signal according to a driving current generated by the amplifier. When the control circuit determines that the amplifier operates in a high power mode, the control circuit controls the control signal to adjust a conducting level between the first terminal and the second terminal of the switch circuit according to the intensity of the driving current.

According to one embodiment, a semiconductor circuit includes: an amplifier including an input terminal; an output circuit including a first node connected to the amplifier, and first and second output terminals, the output circuit performing a first output mode using one of the first and second output terminals or a second output mode using the first and second output terminals; and a bypass circuit between the input terminal and the first node. The output circuit includes a first switch between a second node and the first output terminal, a second switch between a third node and the second output terminal, a third switch between the second and third nodes, a first passive circuit connected to the second node, a second passive circuit connected to the third node, and a third passive circuit between the second and third nodes.

An amplifier circuit configuration capable of processing non-contiguous intra-band carrier aggregate (CA) signals using amplifiers is disclosed herein. In some cases, each of a plurality of amplifiers is an amplifier configured as a cascode (i.e., a two-stage amplifier having two transistors, the first configured as a “common source” input transistor, e.g., input field effect transistor (FET), and the second configured in a “common gate” configuration as a cascode output transistor, (e.g. cascode output FET). In other embodiments, the amplifier may have additional transistors (i.e., more than two stages and/or stacked transistors). The amplifier circuit configuration can be operated in either single mode or split mode. A switchable coupling is placed between the drain of the input FETs of each amplifier within the amplifier circuit configuration. During split mode, the coupling is added to the circuit to allow some of the signal present at the drain of each input FET to be coupled to the drain of the other input FET.

A receiver front end amplifier capable of receiving and processing intraband non-contiguous carrier aggregate (CA) signals using multiple low noise amplifiers (LNAs) is disclosed herein. A cascode having a “common source” configured input FET and a “common gate” configured output FET can be turned on or off using the gate of the output FET. A first switch is provided that allows a connection to be either established or broken between the source terminal of the input FET of each LNA. Further switches used for switching degeneration inductors, gate capacitors, and gate to ground capacitors for each leg can be used to further improve the matching performance of the invention.

An LNA having a plurality of paths, each of which can be controlled independently to achieve a gain mode. Each path includes at least an input FET and an output FET coupled in series. A gate of the output FET is controlled to set the gain of the LNA. Signals to be amplified are applied to the gate of the input FET. Additional stacked FETs are provided in series between the input FET and the output FET.

Methods and devices used in mobile receiver front end to support multiple paths and multiple frequency bands are described. The presented devices and methods provide benefits of scalability, frequency band agility, as well as size reduction by using one low noise amplifier per simultaneous outputs. Based on the disclosed teachings, variable gain amplification of multiband signals is also presented.

An amplifier for converting a single-ended input signal to a differential output signal. The amplifier comprises a first transistor, a second transistor, a third transistor and a fourth transistor. The first transistor, configured in common-source or common-emitter mode, receives the single-ended input signal and generates a first part of the differential output signal. The second transistor, also configured in common-source or common-emitter mode, generates a second part of the differential output signal. The third and fourth transistors are capacitively cross-coupled. The amplifier further comprises inductive degeneration such that a source or emitter of the first transistor is connected to a first inductor and a source or emitter of the second transistor is connected to a second inductor.

A semiconductor device includes three transistors, five switches, two inductors, and a capacitor. A first transistor has a gate. The switches have one terminal connected in series with a drain of the first transistor in parallel. A second transistor has a source connected to the first switch and a grounded gate. A third transistor having a source connected to the second switch and a grounded gate. A first inductor and a second inductor each has one terminal connected in series with the third switch in parallel. A fourth switch has one terminal connected to the first inductor and another terminal connected to the source of the second transistor. A fifth switch has one terminal connected to the second inductor and another terminal connected to the source of the third transistor. A capacitor connected between the one terminal of the fourth switch and the one terminal of the fifth switch.