One example includes a device that is comprised of a pre-power amplifier, a power amplifier, a signal path, and a dynamic bias circuit. The pre-power amplifier amplifies an input signal and outputs a first amplified signal. The power amplifier receives the first amplified signal and amplifies the first amplified signal based on a dynamic bias signal to produce a second amplified signal at an output thereof. The signal path is coupled between an output of the pre-power amplifier and an input of the power amplifier. The dynamic bias circuit monitors the first amplified signal, generates the dynamic bias signal, and outputs the dynamic bias into the signal path.

The invention relates to a radio frequency oscillator, the radio frequency oscillator comprising a resonator circuit being resonant at an excitation of the resonator circuit in a differential mode and at an excitation of the resonator circuit in a common mode, wherein the resonator circuit has a differential mode resonance frequency at the excitation in the differential mode, and wherein the resonator circuit has a common mode resonance frequency at the excitation in the common mode, a first excitation circuit being configured to excite the resonator circuit in the differential mode to obtain a differential mode oscillator signal oscillating at the differential mode resonance frequency, and a second excitation circuit being configured to excite the resonator circuit in the common mode to obtain a common mode oscillator signal oscillating at the common mode resonance frequency.

The invention relates to a radio frequency oscillator, the radio frequency oscillator comprising a resonator circuit being resonant at an excitation of the resonator circuit in a differential mode and at an excitation of the resonator circuit in a common mode, wherein the resonator circuit has a differential mode resonance frequency at the excitation in the differential mode, and wherein the resonator circuit has a common mode resonance frequency at the excitation in the common mode, a first excitation circuit being configured to excite the resonator circuit in the differential mode to obtain a differential mode oscillator signal oscillating at the differential mode resonance frequency, and a second excitation circuit being configured to excite the resonator circuit in the common mode to obtain a common mode oscillator signal oscillating at the common mode resonance frequency.

A mixer includes a load portion connected between an input terminal of a first power voltage and an output terminal of the radio frequency transmit signal and configured to adjust a magnitude of the radio frequency transmit signal, a first switching unit connected to an output terminal of the radio frequency transmit signal, and configured to perform a first switching operation in response to a plurality of local oscillation signals, and a second switching unit connected between the first switching unit and an input terminal of a second power voltage, lower than the first power voltage, and configured to perform a second switching operation in response to a plurality of baseband signals, the plurality of local oscillation signals include an I+ baseband signal, an I− baseband signal, a Q+ baseband signal, and a Q− baseband signal, and the second switching unit includes a first branch performing a switching operation under control of the I+ baseband signal and the Q+ baseband signal, a second branch performing a switching operation under control of the I− baseband signal and the Q− baseband signal, a third branch performing a switching operation under control of the Q+ baseband signal and the I− baseband signal, and a fourth branch performing a switching operation under control of the Q− baseband signal and the I+ baseband signal.

A mixer includes a load portion connected between an input terminal of a first power voltage and an output terminal of the radio frequency transmit signal and configured to adjust a magnitude of the radio frequency transmit signal, a first switching unit connected to an output terminal of the radio frequency transmit signal, and configured to perform a first switching operation in response to a plurality of local oscillation signals, and a second switching unit connected between the first switching unit and an input terminal of a second power voltage, lower than the first power voltage, and configured to perform a second switching operation in response to a plurality of baseband signals, the plurality of local oscillation signals include an I+ baseband signal, an I− baseband signal, a Q+ baseband signal, and a Q− baseband signal, and the second switching unit includes a first branch performing a switching operation under control of the I+ baseband signal and the Q+ baseband signal, a second branch performing a switching operation under control of the I− baseband signal and the Q− baseband signal, a third branch performing a switching operation under control of the Q+ baseband signal and the I− baseband signal, and a fourth branch performing a switching operation under control of the Q− baseband signal and the I+ baseband signal.

Provided is a dual-drive based Doherty amplifier that includes a first power amplifier and a second power amplifier that is in parallel with the first power amplifier. The first power amplifier is configured to receive a first portion of a signal having a first phase, and the second power amplifier is configured to receive a second portion of the signal having a second phase that has a phase difference from the first phase. At least one of the first power amplifier or the second power amplifier includes a dual-drive power amplifier core.

An amplifier system includes an amplifier transistor and a reference transistor used to provide a direct current (DC) bias voltage to bias a gate terminal of the amplifier transistor. The amplifier transistor may have a drain terminal coupled to a drain voltage supply and a radio frequency (RF) output node and a gate terminal coupled to bias circuitry that includes the reference transistor. The reference transistor may have a gate terminal coupled to a reference potential, a drain terminal coupled to the drain voltage supply, and a source terminal coupled to a constant current source and to the gate terminal of the amplifier transistor. The reference transistor may be formed on the same die as the amplifier transistor and may have a threshold voltage that is correlated with that of the amplifier transistor.

Various methods and circuital arrangements for biasing one or more gates of stacked transistors of an amplifier are possible where the amplifier is configured to operate in at least an active mode and a standby mode. Circuital arrangements can reduce bias circuit and stacked transistors standby current during operation in the standby mode and to reduce impedance presented to the gates of the stacked transistors during operation in the active mode while maintaining voltage compliance of the stacked transistors during both modes of operation.

Various methods and circuital arrangements for biasing one or more gates of stacked transistors of an amplifier are possible where the amplifier is configured to operate in at least an active mode and a standby mode. Circuital arrangements can reduce bias circuit and stacked transistors standby current during operation in the standby mode and to reduce impedance presented to the gates of the stacked transistors during operation in the active mode while maintaining voltage compliance of the stacked transistors during both modes of operation.

Embodiments are provided that enhance ultrasound efficacy by for example, high efficiency, signal measurement, calibration, and assurance systems with a control system radio-frequency (RE) driver configured to drive one or more focused ultrasound transducers. The RE driver can comprise one or more power amplifiers including one or more III-V semiconductors, (e.g., gallium nitride GaN, GaAs, GaSb, InP, InAs, InSb, InGaAs, AlSb, AlGaAs, and/or AlGaN) field-effect transistors to efficiently provide high power with distinct narrow-band RE signals over a wide frequency range. The RE driver can include a power measurement and/or calibration system to monitor the amplitude and phase of the RE signal output from the power amplifier and estimate the amount of RE power delivered to the ultrasound transducers.