A filter device configured to directly connect to a differential power amplifier of a transmit chain circuit. The filter device may include a transformer and a filter configured as a half lattice equivalent topology and having a single-ended output. The filter may be a lattice filter configured as a full lattice topology or a lattice equivalent filter configured as a half lattice equivalent topology. The filter includes a first branch having a first impedance network of one or more first impedance elements and a second branch having a second impedance network of one or more second impedance elements. The single-ended output of the filter device may connect to an antenna switch that is in turn connected to an antenna.

A radio frequency (RF) transistor amplifier package includes a submount, and first and second leads extending from a first side of the submount. The first and second leads are configured to provide RF signal connections to one or more transistor dies on a surface of the submount. At least one rivet is attached to the surface of the submount between the first and second leads on the first side. One or more corners of the first side of the submount may be free of rivets. Related devices and associated RF leads and non-RF leads are also discussed.

An integrated circuit includes a first amplifier and a second amplifier. A first impedance matching circuit is coupled to the first amplifier, a first charge pump, and a single MEMS transducer. A second impedance matching circuit is coupled to the second amplifier, a second charge pump, and to the single MEMS transducer. A first capacitive load as measured at an input of first amplifier, and a second capacitive load as measured at an input of the second amplifier exist. The first capacitive load and the second capacitive load are balanced with respect to each other. A single pressure change causes the single MEMS transducer to create a first electrical signal and a second electrical signal. Both the first electrical signal and the second electrical signal are matched or approximately matched in magnitude, and 180 degrees or approximately 180 degrees out of phase with respect to each other.

An integrated circuit includes a first amplifier and a second amplifier. A first impedance matching circuit is coupled to the first amplifier, a first charge pump, and a single MEMS transducer. A second impedance matching circuit is coupled to the second amplifier, a second charge pump, and to the single MEMS transducer. A first capacitive load as measured at an input of first amplifier, and a second capacitive load as measured at an input of the second amplifier exist. The first capacitive load and the second capacitive load are balanced with respect to each other. A single pressure change causes the single MEMS transducer to create a first electrical signal and a second electrical signal. Both the first electrical signal and the second electrical signal are matched or approximately matched in magnitude, and 180 degrees or approximately 180 degrees out of phase with respect to each other.

A class-D amplifier includes measurement of speaker current via the low-side drive transistors of the amplifier. In one embodiment, a class-D amplifier includes two high-side transistors, two low-side transistors, a first sense resistor, a second sense resistor, and a sigma delta analog to digital converter (σΔ ADC). The two high-side transistors and two low-side transistors are connected as a bridge to drive a bridge tied speaker. The first sense resistor is connected between a first of the low-side transistors and a low-side reference voltage. The second sense resistor is connected between a second of the low-side transistors and the low-side reference voltage. The ΣΔ ADC is coupled to the bridge to measure voltage across the first sense resistor and the second sense resistor.

A class D amplifier circuit receives an analog audio signal with a first reference voltage as its center level, and outputs an output pulse signal having a duty cycle that corresponds to the analog audio signal. A bias circuit generates a second reference voltage having a voltage level obtained as a division of the first reference voltage and the power supply voltage. A periodic voltage generating circuit of the class D amplifier circuit generates a periodic voltage having a triangle waveform or otherwise a sawtooth waveform having an amplitude that corresponds to the second reference voltage.

Aspects of the present disclosure relate to apparatus and methods for dynamically adjusting the common-mode input signal of a power amplifier, such as a class-D power amplifier. One example power amplifier circuit generally includes a first amplifier having a signal input and a power input; and a common-mode adjustment circuit having a first input coupled to the power input of the first amplifier, having an output coupled to the signal input of the first amplifier, and being configured to generate a common-mode signal to apply to the signal input of the first amplifier, based on a power supply voltage on the power input of the first amplifier.

A power supply circuit in a wireless communications system includes an envelope tracking modulator coupled to a first power amplifier circuit and a second power amplifier circuit, so that the power supply circuit supplies power to the first power amplifier circuit and the second power amplifier circuit. When a transmit signal output by a processor is within a first bandwidth range, the power supply circuit supplies power to the first power amplifier circuit, and the first power amplifier circuit amplifies power of the transmit signal. When the transmit signal output by the processor meets a second bandwidth range, the power supply circuit supplies power to the second power amplifier circuit, and the second power amplifier circuit amplifies the transmit signal.

An audio preamplifier (1) for a microphone, including: a chassis (2) with at least one audio input (17) and at least one audio output, a control panel (3) including a gain selector (10) being arranged on one of the sides of the chassis (2), the chassis (2) further including a receiving compartment inside which a first connector is arranged; and a cartridge (6) comprising a preamplification circuit and a gain control circuit, the cartridge (6) further having a second connector complementary to the first connector, the cartridge (6) being configured for being inserted in a removable manner into the receiving compartment of the chassis (2) so as to connect the first and second connectors. An audio preamplification kit includes an audio preamplifier (1) and a plurality of additional cartridges.

An apparatus for amplifying an audio source includes a speaker and a chip. The chip includes a processor configured to generate a signal and an amplifier element configured to amplify the signal into an amplified signal. The chip further includes a current monitor configured to monitor the current of the amplified signal prior to the amplified signal being output from the chip to the speaker and a voltage monitor configured to monitor the voltage of the amplified signal prior to the amplified signal being output from the chip to the speaker. The processor of the chip is configured to control a power of the amplified signal output from the chip to the speaker based at least on the current and the voltage.