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.

A high frequency semiconductor amplifier according to the present disclosure includes: a transistor formed on a semiconductor substrate and including a gate electrode, a source electrode, and a drain electrode; a matching circuit for input-side fundamental wave matching of the transistor; a first inductor formed on the semiconductor substrate and having one end connected to the gate electrode of the transistor and the other end connected to the matching circuit; a capacitor formed on the semiconductor substrate and having one end being short-circuited; and a second inductor formed on the semiconductor substrate and having one end connected to the gate electrode of the transistor and the other end connected to the other end of the capacitor, wherein the second inductor resonates in series with the capacitor at second harmonic frequency, has a mutual inductance of subtractive polarity with the first inductor, and the first inductor and the second inductor form mutual inductive circuits for input-side second harmonic matching.

A high frequency semiconductor amplifier according to the present disclosure includes: a transistor formed on a semiconductor substrate and including a gate electrode, a source electrode, and a drain electrode; a matching circuit for input-side fundamental wave matching of the transistor; a first inductor formed on the semiconductor substrate and having one end connected to the gate electrode of the transistor and the other end connected to the matching circuit; a capacitor formed on the semiconductor substrate and having one end being short-circuited; and a second inductor formed on the semiconductor substrate and having one end connected to the gate electrode of the transistor and the other end connected to the other end of the capacitor, wherein the second inductor resonates in series with the capacitor at second harmonic frequency, has a mutual inductance of subtractive polarity with the first inductor, and the first inductor and the second inductor form mutual inductive circuits for input-side second harmonic matching.

A power amplifier including a first transistor for amplifying and outputting a radio frequency signal, a second transistor, a third transistor for supplying a bias current, a first voltage supply circuit for supplying a lower voltage to a base of the third transistor as a temperature of a first diode is higher. The third transistor and the first transistor, or the third transistor and the second transistor, are disposed without another electronic element interposed therebetween. The third transistor is disposed such that a distance between the third transistor and the first transistor is smaller than a distance between the first voltage supply circuit and the first transistor, or a distance between the third transistor and the second transistor is smaller than a distance between the first voltage supply circuit and the second transistor.

A power amplifier including a first transistor for amplifying and outputting a radio frequency signal, a second transistor, a third transistor for supplying a bias current, a first voltage supply circuit for supplying a lower voltage to a base of the third transistor as a temperature of a first diode is higher. The third transistor and the first transistor, or the third transistor and the second transistor, are disposed without another electronic element interposed therebetween. The third transistor is disposed such that a distance between the third transistor and the first transistor is smaller than a distance between the first voltage supply circuit and the first transistor, or a distance between the third transistor and the second transistor is smaller than a distance between the first voltage supply circuit and the second transistor.

A radio frequency (RF) power amplifier (PA) for amplifying an RF signal between a source node and an output node, the RF PA including a silicon substrate with a complementary metal oxide semiconductor (CMOS) N-type transistor with a source region and a drain region fabricated therein. The source region includes the source node of the RF PA and the drain region includes the output node of the RF PA. The RF PA includes a planar resistor fabricated on the surface of the silicon substrate proximal to the drain region of the N-type transistor, wherein the resistor provides a thermal source for heating the RF PA; and a control circuit providing thermal heating to the RF PA by providing power to the planar resistor during RF signal bursts wherein the added thermal heating compensates transient heating within the transistor and results in a linear power amplification operation.

A radio frequency (RF) power amplifier (PA) for amplifying an RF signal between a source node and an output node, the RF PA including a silicon substrate with a complementary metal oxide semiconductor (CMOS) N-type transistor with a source region and a drain region fabricated therein. The source region includes the source node of the RF PA and the drain region includes the output node of the RF PA. The RF PA includes a planar resistor fabricated on the surface of the silicon substrate proximal to the drain region of the N-type transistor, wherein the resistor provides a thermal source for heating the RF PA; and a control circuit providing thermal heating to the RF PA by providing power to the planar resistor during RF signal bursts wherein the added thermal heating compensates transient heating within the transistor and results in a linear power amplification operation.

A packaged RF power amplifier (RFPA) configured to increase video bandwidth is disclosed as well is a process for implementing a RF power device to increase video bandwidth. The RF power device including at least one transistor; an output matching circuit coupled to an output lead and to the at least one transistor; at least one bias feed circuit coupled to the at least one transistor; and at least one coaxial resonator coupled between the at least one transistor and the at least one bias feed circuit.

A packaged RF power amplifier (RFPA) configured to increase video bandwidth is disclosed as well is a process for implementing a RF power device to increase video bandwidth. The RF power device including at least one transistor; an output matching circuit coupled to an output lead and to the at least one transistor; at least one bias feed circuit coupled to the at least one transistor; and at least one coaxial resonator coupled between the at least one transistor and the at least one bias feed circuit.

Disclosed is a voltage detector and a communication circuit capable of detecting a low input voltage. The voltage detector includes: an alternating-current coupling circuit generating a first and a second input voltages according to a source input voltage; a feedback amplifier outputting a branch current according to a sink current including the branch current, and determining an output voltage according to the first input voltage and the amount of the branch current; and an auxiliary circuit outputting the amount of the sink current according to the second input voltage. When the sink current increases as the second input voltage rises, the branch current also increases, so that the output voltage not only rises as the first input voltage rises but also rises as the branch current increases. This feature allows a lower input voltage to be detectable by the detection of the risen output voltage.