An embodiment of a module (e.g., an amplifier module) includes a substrate, a transmission line, and a ground plane height variation structure. The substrate is formed from a plurality of dielectric material layers, and has a mounting surface and a second surface opposite the mounting surface. A plurality of non-overlapping zones is defined at the mounting surface. The transmission line is coupled to the substrate and is located within a first zone of the plurality of non-overlapping zones. The ground plane height variation structure extends from the second surface into the substrate within the first zone. The ground plane height variation structure underlies the transmission line, a portion of the substrate is present between the upper boundary and the transmission line, and the ground plane height variation structure includes a conductive path between an upper boundary of the ground plane height variation structure and the second surface.

Apparatus and methods for oscillation suppression of cascode power amplifiers are provided herein. In certain implementations, a power amplifier system includes a cascode power amplifier including a plurality of transconductance devices that operate in combination with a plurality of cascode devices to amplify a radio frequency input signal. The power amplifier system further includes a bias circuit that biases the plurality of cascode devices with two or more bias voltages that are decoupled from one another at radio frequency to thereby inhibit the cascode power amplifier from oscillating.

In one form, a signal generator system such as a power amplifier system includes an amplification stage, a lowpass filter, and a controller. The amplification stage includes a first amplifier having an input for receiving an input signal, a control input for receiving a first control signal, and an output. The lowpass filter has a first input coupled to the output of the first amplifier, and an output. The controller has a first input coupled to the output of the lowpass filter, and a first output coupled to the control input of the first amplifier, wherein the controller varies the first control signal to reduce a difference between the output of the lowpass filter and a first target voltage level.

Aspects generally relate to reducing delay, or phase jitter, in high speed signals transmission. Variations in power supply to ground potential changes the amount of delay introduced by transmit circuitry into the signal being transmitted, resulting in jitter, or phase noise, in the transmitted signal. To reduce phase jitter, or phase noise, aspects disclosed include a variable impedance circuit coupled to the signal distribution network, the impedance level of the variable impedance circuit is adjusted in response to variation in the supply to ground potential, such that the delay introduced by the impedance compensates for changes in the delay due to variations in supply to ground potential, resulting in substantially constant delay.

A control circuit includes a first output unit configured to output a constant bias current for setting an electrical bias state of a bias circuit to the bias circuit; a second output unit configured to output a bias control current or constant voltage for controlling the electrical bias state of the bias circuit to the bias circuit; a resistor having one end connected to a reference potential; and a switch provided between another end of the resistor and an output terminal of the second output unit.

A hearing prosthesis circuit includes a power source, a first amplifier coupled to the power source, and a second amplifier coupled to the power source. The circuit also includes a stimulation component coupled to the first amplifier and the second amplifier. The stimulation component is configured to provide an output in accordance with an electrical signal that includes audio data. Further, the circuit includes a controller coupled to the first amplifier and the second amplifier. The controller is operable in accordance with a first operational setting to use the first amplifier to provide the electrical signal to the stimulation component and the controller is also operable in accordance with a second operational setting to use the second amplifier to provide the electrical signal to the stimulation component. Generally, the first amplifier provides greater signal amplification of the audio data than the second amplifier.

A communication unit includes a first input terminal to which a first transmission signal based on a first communication standard is input, a second input terminal to which a second transmission signal based on a second communication standard is input, a first transmission signal amplifier circuit outputting a first amplified transmission signal, or outputting a second amplified transmission signal, a first input-output terminal outputting the first amplified transmission signal or the second amplified transmission signal, and at least one of a first reception signal and a second reception signal inputted to the first input-output terminal, a first reception signal amplifier circuit performing at least one of operation of outputting a first amplified reception signal and operation of outputting a second amplified reception signal, a first output terminal outputting the first amplified reception signal, and a second output terminal outputting the second amplified reception signal.

Methods and apparatus for providing high efficiency power amplifiers for both high and low output power levels are disclosed. An example apparatus includes a first amplifier to amplify a signal from a host device; and transmit the amplified signal to an antenna; a second amplifier to amplify the signal from the host device; and transmit the amplified signal to the antenna; and first, second, and third switches to: when the first and second switches are closed and the third switch is open, couple the first amplifier to the second amplifier in a parallel structure; and when the first and second switches are open and the third switch is closed, couple the first amplifier to the second amplifier in a stacked structure.

A communication circuit may include a first pair of digital-to-analog converters (DACs) coupled to an input of a first mixer and configured to generate first baseband signals. The communication circuit may further include a second pair of DACs coupled to an input of a second mixer and configured to generate second baseband signals. The second baseband signals may be shifted in phase relative to the first baseband signals.

Apparatus and methods of calibrating a power amplifier system to compensate for envelope amplitude misalignment are provided. In certain configurations, a method of calibrating a power amplifier system includes generating a supply voltage of a power amplifier using an envelope tracker based on shaping a scaled envelope signal using shaping data generated at a target gain compression, controlling a variable gain of a variable gain amplifier based on a gain control level signal, changing the variable gain by adjusting the gain control level signal using a calibration module, monitoring an output of the power amplifier to determine an amount of variable gain at which a detected gain compression of the power amplifier corresponds to the target gain compression of the shaping data, and calibrating the power amplifier system to compensate for envelope amplitude misalignment based on the determined amount of variable gain.