Provided in the present invention are a linear compensation method for a radio frequency amplifier and a magnetic resonance imaging system. The linear compensation method for a radio frequency amplifier includes determining a working voltage of the radio frequency amplifier, determining a corresponding linear compensation value based on the working voltage, and performing linear compensation on the radio frequency amplifier based on the linear compensation value.

Measurement of signal power for variable or time varying signals. A log-linear VGA coupled in a feedback configuration to a difference detector and an integrator, includes a set of amplifier cells selectable by a sliding current generator, producing a sum of outputs. Outputs of the sliding current generator include a first control current provided using a sum of amplified currents, a sequence of intermediate control currents, and a final control current provided using a sum of amplified currents. Control currents to be summed can be differentially amplified or attenuated; attenuators include capacitors to compensate for capacitive loading. Selectable amplifier cells are differentially amplified or attenuated. Isolating switches and canceling stages reduce the effects of leakage between adjacent amplifier cells. The sliding current generator can have boosted current to first and last amplifier cells, providing a more linear-in-dB gain near a relative maximum or minimum.

The present disclosure provides for process and temperature compensation in a transimpedance amplifier (TIA) using a dual replica via monitoring an output of a first TIA (transimpedance amplifier) and a second TIA; configuring a first gain level of the first TIA based on a feedback resistance and a reference current applied at an input to the first TIA; configuring a second gain level of the second TIA and a third TIA based on a control voltage; and amplifying a received electrical current to generate an output voltage using the third TIA according to the second gain level. In some embodiments, one or both of the second TIA and the third TIA include a configurable feedback impedance used in compensating for changes in the second gain level due to a temperature of the respective second or third TIA via the configurable feedback impedance of the respective second or third TIA.

The present disclosure provides for process and temperature compensation in a transimpedance amplifier (TIA) using a dual replica via monitoring an output of a first TIA (transimpedance amplifier) and a second TIA; configuring a first gain level of the first TIA based on a feedback resistance and a reference current applied at an input to the first TIA; configuring a second gain level of the second TIA and a third TIA based on a control voltage; and amplifying a received electrical current to generate an output voltage using the third TIA according to the second gain level. In some embodiments, one or both of the second TIA and the third TIA include a configurable feedback impedance used in compensating for changes in the second gain level due to a temperature of the respective second or third TIA via the configurable feedback impedance of the respective second or third TIA.

The invention relates to a signal amplifier circuit for amplifying a signal, in particular an audio amplifier circuit, includes at least one first amplifier transistor (Q1) and at least one second amplifier transistor (Q2), wherein the first amplifier transistor (Q1) and the second amplifier transistor (Q2) are connected to one another in a push-pull circuit and are fed by an amplifier voltage source (V+, V−); and one or more bias diodes (D1, D2) thermally coupled in each case to an associated amplifier transistor (Q1, Q2), wherein the bias diodes (D1, D2) are arranged in a parallel connection with respect to the amplifying transistors (Q1, Q2) to reduce or avoid a crossover distortion, wherein the bias diodes (D1, D2) are fed at least partly by a voltage source (UA) which is independent of the amplifier voltage source (V+, V−). The invention furthermore relates to a system and a voltage converter for providing an output-side DC voltage, including a first transformer (T1) and a second transformer (T2) connected to the first transformer (T1).

The present disclosure relates to an amplifying circuit and a voltage generating circuit. The amplifying circuit includes: an operational amplifier, including a first input terminal, a second input terminal and an output terminal, and configured to be capable of outputting an output voltage corresponding to an input voltage from the output terminal to the first input terminal; a voltage dividing circuit, including a series circuit of a plurality of voltage dividing resistors disposed between the output terminal and a predetermined potential terminal, wherein the series circuit includes a feedback node connected to the second input terminal and a correction node different from the feedback node; and a correction circuit, including a diode inserted between the correction node and the predetermined potential terminal.

A power amplifier circuit includes a first power supply terminal electrically connected to a first power amplifier; a second power supply terminal electrically connected to a second power amplifier subsequent to the first power amplifier; a first external power supply line configured to electrically connect a power supply circuit configured to output a power supply potential corresponding to an amplitude level of a high-frequency input signal and the first power supply terminal; and a second external power supply line configured to electrically connect the power supply circuit and the second power supply terminal. An inductance value of the first external power supply line is higher than an inductance value of the second external power supply line.

A method for powering an audio amplifier includes receiving an input audio signal in an audio signal processor, delaying the input audio signal in the audio signal processor to generate a delayed audio signal, predicting a power demand estimate by analyzing the input audio signal to calculate the power demand estimate in the audio signal processer, and selecting, by the audio signal processor, power conversion settings for a DC to DC converter on the basis of the power demand estimate. The method further includes supplying power input to the DC to DC converter, converting the power input in accordance with the power conversion settings to provide a power output, powering the audio amplifier using the power output, and supplying the delayed audio signal to the audio amplifier from the audio signal processor to generate an amplified audio signal.

A method for powering an audio amplifier includes receiving an input audio signal in an audio signal processor, delaying the input audio signal in the audio signal processor to generate a delayed audio signal, predicting a power demand estimate by analyzing the input audio signal to calculate the power demand estimate in the audio signal processer, and selecting, by the audio signal processor, power conversion settings for a DC to DC converter on the basis of the power demand estimate. The method further includes supplying power input to the DC to DC converter, converting the power input in accordance with the power conversion settings to provide a power output, powering the audio amplifier using the power output, and supplying the delayed audio signal to the audio amplifier from the audio signal processor to generate an amplified audio signal.

An envelope tracking (ET) power amplifier apparatus is provided. The ET power amplifier apparatus includes an amplifier circuit configured to amplify a radio frequency (RF) signal based on an ET voltage and a tracker circuit configured to generate the ET voltage based on an ET target voltage. The ET power amplifier apparatus also includes a control circuit. The control circuit is configured to dynamically determine a voltage standing wave ratio (VSWR) change at a voltage output relative to a nominal VSWR and cause an adjustment to the ET voltage. By dynamically determining the VSWR change and adjusting the ET voltage in response to the VSWR change, the amplifier circuit can operate under a required EVM threshold across all phase angles of the RF signal.