An impedance matching device includes: a variable capacitor in which a plurality of first capacitance elements or a plurality of second capacitance elements are connected in parallel; a calculation unit that calculates an impedance or a reflection coefficient on the load side using information regarding the impedance acquired from the outside; and a control unit that determines an ON/OFF state to be taken by each of semiconductor switches included in the variable capacitor using the impedance or the reflection coefficient calculated by the calculation unit and turns on or off the semiconductor switches included in the first or second capacitance element based on the determined state. The control unit cyclically switches semiconductor switches to be turned on or off in a predetermined order.

A filter assembly is disclosed that includes a monolithic filter having a surface and a heat sink coupled to the surface of the monolithic filter. The heat sink includes a layer of thermally conductive material that can have a thickness greater than about 0.02 mm. The heat sink may provide electrical shielding for the monolithic filter. In some embodiments, the filter assembly may include an organic dielectric material, such as liquid crystalline polymer or polyphenyl ether. In some embodiments, the filter assembly may include an additional monolithic filter.

Aspects of this disclosure relate to a filter that includes an acoustic wave device with a multi-layer substrate with heat dissipation. The multi-layer substrate includes a support substrate (e.g., a quartz substrate), a piezoelectric layer, an interdigital transducer electrode on the piezoelectric layer, and a thermally conductive layer configured to dissipate heat associated with the acoustic wave device. The thermally conductive layer is disposed between the support substrate and the piezoelectric layer. The thermally conductive layer has a thickness that is greater than 10 nanometers and less than a thickness of the piezoelectric layer.

The circuit device includes a current generation circuit configured to generate a temperature compensation current based on a temperature detection voltage, and a current-voltage conversion circuit configured to perform current-voltage conversion on the temperature compensation current to output a temperature compensation voltage. The current-voltage conversion circuit includes an operational amplifier, and a feedback circuit. The operational amplifier includes a differential section having a current mirror circuit and differential pair transistors, an output section configured to output the temperature compensation voltage, and an RC low-pass filter configured to output a signal obtained by performing a low-pass filter process on an output signal of the differential section to an input node of the output section.

The circuit device includes a current generation circuit configured to generate a temperature compensation current based on a temperature detection voltage, and a current-voltage conversion circuit configured to perform current-voltage conversion on the temperature compensation current to output a temperature compensation voltage. The current-voltage conversion circuit includes an operational amplifier, and a feedback circuit. The operational amplifier includes a differential section having a current mirror circuit and differential pair transistors, an output section configured to output the temperature compensation voltage, and an RC low-pass filter configured to output a signal obtained by performing a low-pass filter process on an output signal of the differential section to an input node of the output section.

A system for thermally protecting an amplifier driving a capacitive load may include a low-pass filter configured to filter, with a variable cutoff frequency, an input signal to generate a filtered input signal, wherein the amplifier is configured to receive the filtered input signal and amplify the filtered input signal to generate a driving signal to the capacitive load and a controller configured to receive a real-time estimate of a temperature associated with the amplifier and vary the variable cutoff frequency as a function of the temperature.

Provided is an impedance matching device for matching an impedance between a high-frequency power source and a load. The impedance matching device pertaining to the present invention is provided with: a matching circuit having variable capacitors, a capacitance of which is adjusted by an ON/OFF operation of a plurality of switches; a switch control unit for performing control for causing states of the switches of the variable capacitors to coincide with a target state in order to adjust the capacitance of the variable capacitors; and a switch state evaluation unit for evaluating whether a switch is in a state requiring suppression of a temperature increase. The switch control unit is configured so that when the switch state evaluation unit evaluates that a switch of the variable capacitors is in a state requiring suppression of a temperature increase, control is performed for suspending changing of a switch state of the switch for a set period and suppressing a temperature increase in the switch.

Provided is an impedance matching device for matching an impedance between a high-frequency power source and a load. The impedance matching device pertaining to the present invention is provided with: a matching circuit having variable capacitors, a capacitance of which is adjusted by an ON/OFF operation of a plurality of switches; a switch control unit for performing control for causing states of the switches of the variable capacitors to coincide with a target state in order to adjust the capacitance of the variable capacitors; and a switch state evaluation unit for evaluating whether a switch is in a state requiring suppression of a temperature increase. The switch control unit is configured so that when the switch state evaluation unit evaluates that a switch of the variable capacitors is in a state requiring suppression of a temperature increase, control is performed for suspending changing of a switch state of the switch for a set period and suppressing a temperature increase in the switch.

Certain aspects of the disclosure are directed to in-phase/quadrature (IQ) mismatch detection and correction in radio frequency receivers. According to a specific example, a method of manufacture or use comprises, in a quadrature radio-frequency receiver configured to process signals using I and Q components, providing parameters indicative of IQ mismatches associated with circuitry of the quadrature radio-frequency receiver due to changes in signal gain. The method further includes, while using the quadrature radio-frequency receiver to receive and process a received radio signal, correcting for the IQ mismatches by using the parameters in response to actual signal gain change.

Certain aspects of the disclosure are directed to in-phase/quadrature (IQ) mismatch detection and correction in radio frequency receivers. According to a specific example, a method of manufacture or use comprises, in a quadrature radio-frequency receiver configured to process signals using I and Q components, providing parameters indicative of IQ mismatches associated with circuitry of the quadrature radio-frequency receiver due to changes in signal gain. The method further includes, while using the quadrature radio-frequency receiver to receive and process a received radio signal, correcting for the IQ mismatches by using the parameters in response to actual signal gain change.