Methods and devices to support multiple gain states in amplifiers are described. The methods and devices are based on implementing a feedback element in the amplifier and adjusting the impedance of the feedback element to provide a desired gain while maintaining the overall performance of the amplifier and reducing degradation of the S12 parameter. The feedback element includes an adjustable attenuator and a tunable resistive element. The adjustable attenuator is provided in a path that is common to the feedback path and the bypass path of the amplifier. Exemplary implementations of adjustable attenuators are also presented.

A half bridge circuit of a class-D amplifier outputs a voltage in accordance with switching of a first switching element and of a second switching element, to a load. A high side gate drive circuit and a low side gate drive circuit respectively drive the first and second switching elements. A bootstrap capacitor connected between the high side gate drive circuit and an output terminal of the half bridge circuit is charged by a charging current from a second direct-current power supply while the first switching element is off. An inductance component for noise suppression, and a voltage limit element that is connected in parallel with the inductance component and is for limiting a voltage that occurs at the inductance component are provided on a path in which the charging current flows.

A circuit includes a comparator to compare an analog signal to a ramp signal to generate a pulse width modulated output signal and a driver to generate control signals for a plurality of power transistors. A pulse blanking circuit receives the pulse width modulated output signal. For each pulse of the pulse width modulated output signal, the pulse blanking circuit, responsive to a width of the pulse being greater than a threshold, passes the pulse to the driver. Responsive to the width of the pulse being less than the threshold, the pulse blanking circuit prevents the pulse from being passed to the driver.

A circuit includes a comparator to compare an analog signal to a ramp signal to generate a pulse width modulated output signal and a driver to generate control signals for a plurality of power transistors. A pulse blanking circuit receives the pulse width modulated output signal. For each pulse of the pulse width modulated output signal, the pulse blanking circuit, responsive to a width of the pulse being greater than a threshold, passes the pulse to the driver. Responsive to the width of the pulse being less than the threshold, the pulse blanking circuit prevents the pulse from being passed to the driver.

A circuit includes a comparator to compare an analog signal to a ramp signal to generate a pulse width modulated output signal and a driver to generate control signals for a plurality of power transistors. A pulse blanking circuit receives the pulse width modulated output signal. For each pulse of the pulse width modulated output signal, the pulse blanking circuit, responsive to a width of the pulse being greater than a threshold, passes the pulse to the driver. Responsive to the width of the pulse being less than the threshold, the pulse blanking circuit prevents the pulse from being passed to the driver.

A circuit includes a comparator to compare an analog signal to a ramp signal to generate a pulse width modulated output signal and a driver to generate control signals for a plurality of power transistors. A pulse blanking circuit receives the pulse width modulated output signal. For each pulse of the pulse width modulated output signal, the pulse blanking circuit, responsive to a width of the pulse being greater than a threshold, passes the pulse to the driver. Responsive to the width of the pulse being less than the threshold, the pulse blanking circuit prevents the pulse from being passed to the driver.

Methods and devices to support multiple gain states in amplifiers are described. The methods and devices are based on implementing a feedback element in the amplifier and adjusting the impedance of the feedback element to provide a desired gain while maintaining the overall performance of the amplifier and reducing degradation of the S12 parameter. The feedback element includes an adjustable attenuator and a tunable resistive element. The adjustable attenuator is provided in a path that is common to the feedback path and the bypass path of the amplifier. Exemplary implementations of adjustable attenuators are also presented.

A half bridge circuit of a class-D amplifier outputs a voltage in accordance with switching of a first switching element and of a second switching element, to a load. A high side gate drive circuit and a low side gate drive circuit respectively drive the first and second switching elements. A bootstrap capacitor connected between the high side gate drive circuit and an output terminal of the half bridge circuit is charged by a charging current from a second direct-current power supply while the first switching element is off. An inductance component for noise suppression, and a voltage limit element that is connected in parallel with the inductance component and is for limiting a voltage that occurs at the inductance component, are provided on a path in which the charging current flows.

Methods and devices to support multiple gain states in amplifiers are described. The methods and devices are based on implementing a feedback element in the amplifier and adjusting the impedance of the feedback element to provide a desired gain while maintaining the overall performance of the amplifier and reducing degradation of the S12 parameter. The feedback element includes an adjustable attenuator and a tunable resistive element. The adjustable attenuator is provided in a path that is common to the feedback path and the bypass path of the amplifier. Exemplary implementations of adjustable attenuators are also presented.