A multi-voltage power generation circuit is disclosed. More specifically, the multi-voltage generation circuit includes multiple voltage modulation circuits that are configured to generate and maintain multiple modulated voltages. In a non-limiting example, the multiple modulated voltages can be used for amplifying multiple radio frequency (RF) signals concurrently. Contrary to using multiple direct-current (DC) to DC (DC-DC) converters for generating the multiple modulated voltages, the voltage modulation circuits are configured to share a single current modulation circuit based on time-division. By sharing a single current modulation circuit among the multiple voltage modulation circuits, it is possible to concurrently support multiple load circuits (e.g., power amplifier circuits) with significantly reduced footprint.

A multi-voltage power generation circuit is disclosed. More specifically, the multi-voltage generation circuit includes multiple voltage modulation circuits that are configured to generate and maintain multiple modulated voltages. In a non-limiting example, the multiple modulated voltages can be used for amplifying multiple radio frequency (RF) signals concurrently. Contrary to using multiple direct-current (DC) to DC (DC-DC) converters for generating the multiple modulated voltages, the voltage modulation circuits are configured to share a single current modulation circuit based on time-division. By sharing a single current modulation circuit among the multiple voltage modulation circuits, it is possible to concurrently support multiple load circuits (e.g., power amplifier circuits) with significantly reduced footprint.

an amplifier having an input terminal and an output terminal. The input terminal is configured to receive a radio frequency (RF) input signal. The device includes an output network coupled to the output terminal of the power amplifier and a first passively tunable integrated circuit (PTIC) coupled to the output network. The first PTIC includes a direct-current (DC) bias voltage input terminal configured to receive a fixed bias voltage, a control signal input terminal configured to receive a time-varying control signal, wherein the fixed bias voltage in combination with the time-varying control signal sets an operating reference point of the first PTIC, and an input terminal electrically connected to the output terminal of the amplifier, wherein a change in an output voltage signal generated by the power amplifier causes the first PTIC to modify a first effective impedance of a load presented to the power amplifier via the output network.

an amplifier having an input terminal and an output terminal. The input terminal is configured to receive a radio frequency (RF) input signal. The device includes an output network coupled to the output terminal of the power amplifier and a first passively tunable integrated circuit (PTIC) coupled to the output network. The first PTIC includes a direct-current (DC) bias voltage input terminal configured to receive a fixed bias voltage, a control signal input terminal configured to receive a time-varying control signal, wherein the fixed bias voltage in combination with the time-varying control signal sets an operating reference point of the first PTIC, and an input terminal electrically connected to the output terminal of the amplifier, wherein a change in an output voltage signal generated by the power amplifier causes the first PTIC to modify a first effective impedance of a load presented to the power amplifier via the output network.

According to at least one example, an amplifier circuit includes an amplifier and a temperature sensor circuit. The temperature sensor circuit includes a first transistor thermally isolated from the amplifier and being configured to sense an ambient temperature, and a second transistor thermally linked to the amplifier and being configured to sense a temperature at the amplifier, the temperature sensor circuit being a differential circuit having a first path and a second path with the first and second transistors being arranged on the first and second paths of the differential circuit respectively. The temperature sensor circuit is configured to generate an output voltage inversely proportional to a temperature difference between the ambient temperature and the temperature at the amplifier.

Examples of the disclosure include an output stage circuit assembly for a power amplifier system, the output stage circuit assembly comprising a plurality of output stage amplifiers connected in parallel to each other, each output stage amplifier of the plurality of output stage amplifiers configured to amplify an input signal of the output stage circuit assembly when turned on, and a controller configured to determine a number of output stage amplifiers to be turned off based on at least one of a voltage supplying mode for the power amplifier system or a power management mode of a device in which the power amplifier system is embedded, and to control the plurality of output stage amplifiers to be turned on or off according to the determined number of output stage amplifiers to be turned off.

The present disclosure provides a magnetic resonance imaging (MRI) radio frequency (RF) coil assembly. The MRI RF coil assembly may include one or more coils and one or more control circuits. Each of the one or more coils may include a first end and a second end. Each of the one or more control circuits may electrically connect the first end and the second end of one of the one or more coil. Each of the one or more control circuits may be configured to adjust an operation of the coil that is electrically connected with the control circuit based on an input control signal. The one or more control circuits may be located at different regions.

An amplifier includes: a high-frequency input terminal; a high-frequency output terminal; a multistage circuit provided between the high-frequency input terminal and the high-frequency output terminal and including two or more amplifiers and connected in series, each amplifier including an input matching circuit, a transistor, and an output matching circuit; a stabilizing circuit provided in at least two of the amplifiers and including a bandpass filter and a resistor connected in parallel; and a band-rejection filter provided between the at least two of amplifiers and eliminating a frequency lower than an operation frequency of the amplifier. The stabilizing circuit and the band-rejection filter are provided between an output terminal of the transistor of the amplifier and the output matching circuit or provided in the output matching circuit. The closer to the high-frequency input terminal the bandpass filter is, the lower a resonance frequency of the bandpass filter is.

An amplifier includes: a high-frequency input terminal; a high-frequency output terminal; a multistage circuit provided between the high-frequency input terminal and the high-frequency output terminal and including two or more amplifiers and connected in series, each amplifier including an input matching circuit, a transistor, and an output matching circuit; a stabilizing circuit provided in at least two of the amplifiers and including a bandpass filter and a resistor connected in parallel; and a band-rejection filter provided between the at least two of amplifiers and eliminating a frequency lower than an operation frequency of the amplifier. The stabilizing circuit and the band-rejection filter are provided between an output terminal of the transistor of the amplifier and the output matching circuit or provided in the output matching circuit. The closer to the high-frequency input terminal the bandpass filter is, the lower a resonance frequency of the bandpass filter is.

A power amplifier system comprises an envelope tracker configured to generate a supply voltage that changes in relation to an envelope of a radio frequency signal, a power amplifier configured to amplify the radio frequency signal, and an adaptation circuit configured to adapt the supply voltage to provide operating power to the power amplifier. The adaptation circuit includes at least one Gallium Nitride field-effect-transistor configured to generate the operating power in response to an increased swing of the supply voltage and at least one linearizing circuit configured to linearize an operation of the Gallium Nitride field-effect-transistor.