A distributed amplifier includes a transmission line configured so as to transmit a signal, a variable capacitor having one end connected to the transmission line and the other end connected to the ground, and configured so that the capacitance is adjustable, and a variable capacitor having one end connected to the transmission line and the other end connected to the ground, and configured so that the capacitance is adjustable. The transmission line is configured in such a manner that the inductance is adjustable.

Described herein are methods for amplifying radio-frequency signals using a variable-gain amplifier with a plurality of input nodes. The methods provide a plurality of gain modes with a low gain mode or bypass mode that follows a bypass path through the variable-gain amplifier and a plurality of higher gain modes that take advantage of tailored impedances for particular gain modes. The tailored impedances can be configured to improve linearity of the amplification process in targeted gain modes. The methods can selectively couple the bypass path to a reference potential node in the plurality of higher gain modes and can selectively decouple the input nodes from a degeneration switching block in the bypass mode.

A receiver front end having 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. A drain switch is provided between the drain terminals of input FETs to place the input FETs in parallel. This increases the g.sub.m of the input stage of the amplifier, thus improving the noise figure of the amplifier.

A low noise amplifier includes a first input port configured to receive a first input signal, a second input port configured to receive a second input signal, and a first amplifier stage including a first gain stage connected to the first input port and the second input port, and a first drive stage between the first gain stage and a first load circuit. The first gain stage includes a first-first gain block connected to the first input port, a first-second gain block connected to the second input port, and a first degeneration inductor between a ground terminal and a first common node of the first-first gain block and the first-second gain block. The amplifier includes a second amplifier stage including a second gain stage connected to the first input port and the second input port, and a second drive stage between the second gain stage and a second load.

In order to reduce costs as well as to effectively dissipate heat in certain RF circuits, a semiconductor device of the circuit can include one or more active devices such as transistors, diodes, and/or varactors formed of a first semiconductor material system integrated onto (e.g., bonded to) a base substrate formed of a second semiconductor material system that includes other circuit components. The first semiconductor material system can, for example, be the III-V or III-N semiconductor system, and the second semiconductor material system can, for example be silicon.

A transistor comprises a drain, a gate, a source, a body terminal and a body resistance. The drain is connected to a supply voltage line to receive a supply voltage. The gate is connected to a control voltage line to receive a control voltage. The source is connected to a input line to receive a input radio frequency signal. The body terminal is connected to the drain. The body resistance is disposed between the drain and the body terminal. By the foregoing configuration, the leakage current of the substrate is reduced and the threshold voltage of the transistor is reduced to conform to the present low power design.

Power amplification system with adjustable common base bias. A power amplification system can include a cascode amplifier coupled to a radio-frequency input signal and coupled to a radio-frequency output. The power amplification system can further include a biasing component configured to apply one or more biasing signals to the cascode amplifier, the biasing component including a bias controller and one or more bias components. Each respective bias component may be coupled to a respective bias transistor.

Power amplification system with adjustable common base bias. A power amplification system can include a cascode amplifier coupled to a radio-frequency input signal and coupled to a radio-frequency output. The power amplification system can further include a biasing component configured to apply one or more biasing signals to the cascode amplifier, the biasing component including a bias controller and one or more bias components. Each respective bias component may be coupled to a respective bias transistor.

A power amplifier circuit includes a power amplifier including a first transistor having a first terminal connected to a reference potential, a second terminal to which a first current and a radio-frequency signal are input, and a third terminal connected to a first power supply potential via a first inductor; a capacitor connected to the third terminal of the first transistor; a second transistor including a first terminal connected to the capacitor and the reference potential via a second inductor, a second terminal to which a second current is input and is connected to the reference potential, and a third terminal connected to the first power supply potential via a third inductor and outputs signal; and an adjustment circuit that outputs a third current corresponding to the first power supply potential or a second power supply potential to the second terminal of the second transistor.

A distributed amplifier includes: a transmission line having an input end that an input signal is input to; a transmission line having an output end that an output signal is output from; an input termination resistor connected to an end terminal of the transmission line; a plurality of unit cells arranged along the transmission lines, and having input terminals connected to the transmission line and output terminals connected to the transmission line; and a variable current source having one end connected to the end terminal of the transmission line and another end connected to a power supply voltage, and capable of adjusting a current amount between the transmission line and the power supply voltage.