Methods, apparatus, systems, and articles of manufacture are disclosed to generate a modulation protocol to output audio. An example apparatus includes a modulation circuit including a first input, a second input, a first output, and a second output; a first gate coupled to the first output of the modulation circuit; a second gate coupled to the second output of the modulation circuit; a first multiplexer including a first input coupled to the first output of the modulation circuit, a second input coupled to the output of the second gate, and an output coupled to a first switch; and a second multiplexer including a first input coupled to the second output of the modulation circuit, a second input coupled to the output of the first gate, and an output coupled to a second switch.

Systems and method for improving operation of a radio frequency system are provided. One embodiment includes a switching power amplifier that outputs an amplified analog electrical signal based on an input electrical signal and voltage of an envelope voltage supply rail. The switching power amplifier includes a first transistor with a gate that receives the input electrical signal, a source electrically coupled to the envelope voltage supply rail, and a drain electrically coupled to an output of the switching power amplifier; a second transistor with a gate that receives the input electrical signal, a source electrically coupled to ground, and a drain electrically coupled to the output; and a third transistor with a gate that receives the input electrical signal, a drain electrically coupled to the envelope voltage supply rail, and a source electrically coupled to an output of another switching power amplifier.

In some implementations, there is provided an apparatus comprising a resonant amplifier circuit including a first inductor having a first inductive input and a first inductive output; a second inductor having a second inductive input and a second inductive output; a first switch coupled to the first inductive output; and a second switch coupled to the second inductive output, wherein the first switch and the second switched are driven out of phase, wherein the first inductor is configured to be resonant with a first capacitance associated with the first switch, and wherein the second inductor is configured to be resonant with a second capacitance associated with the second switch. Related systems and articles of manufacture are also provided.

An audio amplifier with duty ratio control is provided. The audio amplifier comprises a pulse width modulation modulator, a power stage, and a voltage converter. The pulse width modulation modulator is configured to receive an input signal for generating a pulse width modulation signal. The power stage is configured to output an output signal according to a supply voltage and the pulse width modulation signal. The voltage converter is configured to adjust voltage level of the supply voltage according to the pulse width modulation signal. The audio amplifier is configured to adjust the voltage level of the supply voltage when duty ratio of the pulse width modulation signal is greater than a duty ratio threshold.

Techniques are disclosed to allow for a switched capacitor digital power amplifier (PA) that operates using high supply voltage levels beyond twice the maximum voltage rating for any of the transistor terminals such as Vds/Vdg/Vsg.

A signal receiver includes a data sampler receiving a differential input signal having first and second input signals and determining bit values of the differential input signal based on first and second reference voltages, and a reference voltage generator performing a pre-tuning operation and a post-tuning operation to generate the reference voltages. The reference voltage generator performs the pre-tuning operation by generating first and second initial voltages and adjusting one of the initial voltages to generate third and fourth voltages. After the pre-tuning operation, the reference voltage generator performs the post-tuning operation by increasing or decreasing the third voltage to generate the first reference voltage and decreasing or increasing the fourth voltage to generate the second reference voltage based on a comparison result between the third voltage and the first input signal and a second comparison result between the fourth voltage and second input signal.

Apparatus, systems and methods for load-adaptive 3D wireless charging are disclosed. In a 3D charging system of an example embodiment, features comprise a 3D coil design that provides magnetic field distribution coverage for a 3D charging space, e.g.

hemi-spherical space/volume; a push-pull class EF2 PA with EMI filter and transmitter circuitry that provides constant current to the 3D coil, with current direction, phase and timing control capability to adapt to load conditions; reactance shift detection circuitry comprising a voltage sensor, current sensor and phase detector and hardware for fast, real-time, computation of reactance and comparison to upper and lower limits for load-adaptive reactance tuning and for auto-protection; and a switchable tuning capacitor network arrangement of shunt and series capacitors configured for auto-tuning of input impedance, e.g. in response to a X detection trigger signal, which enables both coarse-tuning and uniform fine-tuning steps over an extended reactance range.

It is described a transmitter device (100) and a method for transmitting an analog signal (251, 261) via an electric cable (192). The transmitter device (100) comprises (a) a signal generation circuit (210) for generating a digital transmit signal (211) comprising a sequence of transmit symbols; (b) a filter circuit (230) for spectrally shaping the generated digital transmit signal (211, 221) and for outputting a filtered digital transmit signal (231); (c) a switching unit (240) comprising (c1) a first input terminal (242) for receiving the filtered digital transmit signal (231), (c2) a second input terminal (244) for receiving another digital transmit signal (297), (c3) an output terminal (246) for outputting a digital transmit output signal (241), wherein the digital transmit output signal (241) is based on, depending on a switching state of the switching unit (240), the filtered digital transmit signal (231) or the another digital transmit signal (297), and (c4) a control terminal (248) for receiving a control signal (285) from a control circuit (280), the control signal (285) being indicative for the switching state. The transmitter device (100) further comprises the control circuit (280); and a digital to analog converter (250) for receiving the digital transmit output signal (241) and for converting the received digital transmit output signal (241) to the analog signal (251, 261).

To provide a lightweight and robust voltage amplifier and current amplifier for a test device for testing an electrical component, an amplifier is designed to output a test signal at a signal output between a positive output terminal and a negative output terminal. The amplifier includes a first half bridge and a second half bridge. A switching unit is provided, which is designed to connect the first half bridge and the second half bridge in parallel to the signal output in a first operating mode and to connect the first half bridge and the second half bridge in series with the signal output in a second operating mode.

A method for ramping a switched capacitor power amplifier is disclosed, where the switched capacitor power amplifier comprises a plurality of capacitors in a capacitor bank, and where a number of the capacitors in the capacitor bank are activated. The method comprises changing the number of capacitors in the capacitor bank that are activated, maintaining the changed number of activated capacitors in the capacitor bank for a period of time, and repeating the changing and maintaining, where a length of the period of time is varied between at least two repetitions of the maintaining.