This disclosure describes amplifiers that include impedance circuits that are configured to adapt to various contexts. For example, a variable-gain amplifier can include a gain circuit configured to amplify a signal and to operate in a plurality of gain modes, and an impedance circuit coupled to the gain circuit. The impedance circuit can include an inductor and a switching-capacitive arm coupled in parallel to the inductor. The impedance circuit can be configured to operate based at least in part on a gain mode from among the plurality of gain modes.

An amplifying apparatus includes a variable gain amplifying circuit configured to operate in a gain mode selected from a plurality of gain modes in response to a first control signal during operation in an amplification mode, a variable attenuation circuit configured to have an attenuation value that is adjusted in response to a second control signal, and a phase compensation value which compensates for a phase distortion in the selected gain mode, and a control circuit configured to control the selecting of the gain mode, the adjusting of the attenuation value and the phase compensation value, based on the first and second control signals.

Systems and methods are disclosed for on-chip harmonic filtering for radio frequency (RF) communications. A filtering and matching circuit for an integrated circuit includes a first capacitance coupled in parallel with a first inductance, a second inductance coupled to the first inductance, and a variable second capacitance coupled between the first and second inductance. The variable second capacitance is controlled to provide filtering with respect to the RF signal as well as impedance matching with respect to a load coupled to the connection pad. For one embodiment, the variable second capacitance includes a coarse-tune variable capacitor circuit and a fine-tune variable capacitor circuit. The coarse-tuning controls impedance matching, and the fine tuning controls a notch for the filtering. The load can be an antenna for the RF communications. The integrated circuit can include a receive path, a transmit path, or both.

A programmable transimpedance amplifier (TIA) includes a plurality of signal paths between an output of a common emitter amplifier and the output of the TIA. The TIA is programmed by selecting one of the signal paths, because the paths have different parameters (e.g. different bandwidth). Thus, the bandwidth can be programmed by selecting the appropriate path. The common emitter amplifier's output is coupled to the inputs of common base amplifiers in each path. The inputs have low impedance. Therefore, having multiple paths does not significantly degrade the amplifier performance. High bandwidth can be provided.

A tunable filter is described where the frequency response as well as bandwidth and transmission loss characteristics can be dynamically altered, providing improved performance for transceiver front-end tuning applications. The rate of roll-off of the frequency response can be adjusted to improve performance when used in duplexer applications. The tunable filter topology is applicable for both transmit and receive circuits. A method is described where the filter characteristics are adjusted to account for and compensate for the frequency response of the antenna used in a communication system.

An I-V conversion module includes: a current output type sensor, a pre-integral circuit, a charge transfer auxiliary circuit, and an I-V transformation circuit including an inverting amplifier. The current output type sensor is connected to an input end of the I-V transformation circuit through the pre-integral circuit. The charge transfer auxiliary circuit connects in parallel with the inverting amplifier. When both the pre-integral circuit and the charge transfer auxiliary circuit are open circuits, the pre-integral circuit pre-integrates the induction current output by the current output type sensor to store pre-integral charges. When both pre-integral circuit and the charge transfer auxiliary circuit are closed circuits, the pre-integral charges are transferred to the I-V transformation circuit. In these embodiments, both the time for establishing the I-V conversion module and power consumption can be reduced.

A power amplifier may comprise: an element for amplifying an electrical signal received through an input terminal, and outputting the amplified electrical signal through an output terminal; a first impedance adjustment circuit connected to the input terminal of the element and adjusting impedance with respect to a frequency of a fundamental component at the input terminal; a second impedance adjustment circuit connected to the input terminal of the element and adjusting impedance with respect to a frequency of a multiplied harmonic component at the input terminal; a third impedance adjustment circuit connected to the output terminal of the element and adjusting impedance with respect to the frequency of the fundamental component at the output terminal; a fourth impedance adjustment circuit connected to the output terminal of the element and adjusting impedance with respect to the frequency of the multiplied harmonic component at the output terminal; a first frequency separation circuit which prevents an impedance change by the first impedance adjustment circuit with respect to the frequency of the multiplied harmonic component at the input terminal, and prevents an impedance change by the second impedance adjustment circuit with respect to the frequency of the fundamental component at the input terminal; and a second frequency separation circuit which prevents an impedance change by the third impedance adjustment circuit with respect to the frequency of the multiplied harmonic component at the output terminal, and prevents an impedance change by the fourth impedance adjustment circuit with respect to the frequency of the fundamental component at the output terminal.

Methods and devices addressing design of wideband LNAs with gain modes are disclosed. The disclosed teachings can be used to reconfigure RF receiver front-end to operate in various applications imposing stringent and conflicting requirements. Wideband and narrowband input and output matching with gain modes using a combination of the same hardware and a switching network are also disclosed. The described methods and devices also address carrier aggregation requirements and provide solutions that can be used both in single-mode and split-mode operations.

Methods and devices addressing design of wideband LNAs with gain modes are disclosed. The disclosed teachings can be used to reconfigure RF receiver front-end to operate in various applications imposing stringent and conflicting requirements. Wideband and narrowband input and output matching with gain modes using a combination of the same hardware and a switching network are also disclosed. The described methods and devices also address carrier aggregation requirements and provide solutions that can be used both in single-mode and split-mode operations.

An amplification circuit includes an input terminal, an output terminal, a capacitor, a bias unit, an amplification unit, and an impedance unit. The input terminal receives a radio frequency signal. The capacitor is coupled to the input terminal and the bias unit. The bias unit includes a transistor for controlling the bias current. The transistor has a first terminal for receiving a system voltage, and a control terminal coupled to the reference voltage terminal. The amplification unit has an input terminal coupled to the capacitor and the bias unit, and an output terminal coupled to the output terminal of the amplification circuit. The impedance unit has a first terminal coupled to the bias unit, and a second terminal coupled to the input terminal of the amplification circuit and the capacitor. The impedance unit adjusts the amplifying linearity of the amplification circuit according to a selection signal.