Described herein are variable gain amplifiers and multiplexers that embed programmable attenuators into switchable paths to provide variable gain for individual amplifier inputs. The variable gain for an individual input is provided using a amplification stage that is common for each input of the amplifier. A variable attenuation is provided for individual inputs through a combination of a band selection switch and an attenuation selection branch. The attenuation can be tailored for individual inputs and can depend on a gain mode of the amplifier.

An amplifier for a radio communications system in a shielded tunnel is disclosed. In one example, the amplifier comprises a processor configured to execute a plurality of modules comprising a gain control module and an attenuation control module. Methods and systems are further provided for controlling and monitoring amplifier characteristics.

An output power control device includes: an attenuator to attenuate power of a high-frequency signal output from an oscillator; a high-frequency power amplifier to amplify the power of the high-frequency signal output from the attenuator; a monitor circuit to monitor the power of the high-frequency signal output from the high-frequency power amplifier; and a controller to control an attenuation amount of the attenuator based on the monitor signal output from the monitor circuit or based on attenuation amount setting data from a data unit. The oscillator generates the high-frequency signal in synchronization with a trigger signal. The controller starts control of the attenuation amount of the attenuator based on the attenuation amount setting data, in synchronization with the trigger signal, and, after receiving the monitor signal, the controller controls the attenuation amount of the attenuator based on the monitor signal.

Provided is a power amplification circuit that includes: a first transistor that has an emitter to which a first radio frequency signal is supplied, a base to which a first DC control current or DC control voltage is supplied and a collector that outputs a first output signal that corresponds to the first radio frequency signal; a first amplifier that amplifies the first output signal and outputs a first amplified signal; and a first control circuit that supplies the first DC control current or DC control voltage to the base of the first transistor in order to control output of the first output signal.

Techniques and mechanisms for mitigating signal deterioration in communications between two circuit boards. In an embodiment, a packaged device accommodates coupling to a first circuit board which, in turn, accommodates connection to a second circuit board. In one such embodiment, an amplifier circuit of the packaged device includes an amplifier circuit which comprises a variable resistor and an active circuit element coupled thereto. The device receives via one of the circuit boards a control signal and a voltage which configure the amplifier circuit to provide an impedance matching for communication between the circuit boards. In another embodiment, the device comprises multiple common gate amplifiers which are variously configurable each to provide a respective impedance matching for communications between a motherboard and a dual in-line memory module.

An amplifier for a radio communications system in a shielded tunnel is disclosed. In one example, the amplifier comprises a processor configured to execute a plurality of modules comprising a gain control module and an attenuation control module. Methods and systems are further provided for controlling and monitoring amplifier characteristics.

An inductor includes a substrate, and a first coil pattern disposed on one surface of the substrate and having a spiral shape comprising a plurality of turns, wherein as the first coil pattern extends inwardly towards a center of the first coil pattern, a pattern width of the first coil pattern decreases while a center-to-center distance between two adjacent turns of the first coil pattern increases.

A radio frequency front-end includes a power amplifier. The radio frequency front-end also includes a coupler implemented in at least a portion of a matching circuit, the matching circuit coupled to an output of the power amplifier. The radio frequency front-end further includes a control loop comprising a first feedback terminal at an output of the power amplifier. The control loop includes the coupler coupled to the first feedback terminal of the power amplifier and is configured to generate a feedback signal provided to a second feedback terminal to adjust a gain of the power amplifier. The feedback signal is based on a reflected radio frequency signal provided by the coupler.

Disclosed herein are methods for amplifying a signals. The methods include receiving signals at a plurality of input nodes. The methods also include configuring a gain stage to be in a selected one of a plurality of gain settings, at least some of the gain settings resulting in different impedances presented to the signal. The methods also include adjusting the resistance presented to the signal by the gain stage for the selected gain setting, the adjusted resistance being configured to provide a targeted constant value of the impedance at the input across the plurality of gain settings. The methods also include amplifying at least a portion of the received signals. Adjusting the resistance compensates for changes to the input impedance to improve return loss and mismatch over gain modes.

An apparatus includes an amplifier and a gain control circuit. The amplifier may be configured to provide multiple gain steps. The gain control circuit may be configured to provide fast and precise changes between the multiple gain steps of the amplifier. The gain control circuit may be further configured to change an impedance of the amplifier to switch between the gain steps. The gain control circuit may be further configured to compensate for changes in frequency response related to changing the impedance. The gain control circuit may be further configured to inject a complementary charge to an input of the amplifier to correct a bias voltage deviation and a transient caused by the gain control circuit.