An active device and circuits utilized therewith are disclosed. In an aspect, the active device comprises an n-type transistor having a drain, gate and bulk and a p-type transistor having a drain, gate and bulk. The n-type transistor and the p-type transistor include a common source. The device includes a first capacitor coupled between the gate of the n-type transistor and the gate of the p-type transistor, a second capacitor coupled between the drain of the n-type transistor and the drain of p-type transistor and a third capacitor coupled between the bulk of the n-type transistor and the bulk of p-type transistor. The active device has a high breakdown voltage, is memory less and traps even harmonic signals.

One aspect of the present disclosure relates to a method for operating an amplifier, the amplifier including a variable resistor coupled between a source of a first input transistor and a source of a second input transistors, and a variable capacitor coupled between the source of the first input transistor and the source of the second input transistor. The method includes adjusting a resistance of the variable resistor to adjust a low-frequency gain of the amplifier, and adjusting a capacitance of the variable capacitor in an opposite direction as the adjustment to the resistance of the variable resistor.

The present invention is directed to electrical circuits and techniques thereof. More specifically, an embodiment of the present invention provides a variable gain amplifier that includes a first transistor and a second transistor whose gate terminals are coupled to a first input terminal. A first drain terminal of the first transistor and a first source terminal of the second transistor is coupled to a voltage gain control switch. There are other embodiments as well.

At least one method, apparatus and system disclosed involves providing semiconductor device having transistors comprising back gates and front gates. The semiconductor device comprises a signal processing unit for processing an input signal to provide an output signal. The signal processing unit includes a first transistor and a second transistor. The first transistor includes a first back gate electrically coupled to a first front gate. The signal processing unit also includes a second transistor operatively coupled to the first transistor. The second transistor includes a second back gate electrically coupled to a second front gate. The semiconductor device also includes a gain circuit for providing a gain upon the output signal. The semiconductor device also includes a bias circuit to provide a first bias signal to the first back gate and a second bias signal to the second back gate.

Apparatus and methods for envelope tracking systems with automatic mode selection are provided herein. In certain configurations, a power amplifier system includes a power amplifier that amplifies a radio frequency signal and that receives power from a power amplifier supply voltage. The power amplifier system further includes an envelope tracker that generates the power amplifier supply voltage based on an envelope signal corresponding to an envelope of the radio frequency signal. The envelope tracker includes a signal bandwidth detection circuit that processes the envelope signal to generate a detected bandwidth signal, and a mode control circuit that controls a mode of the error amplifier based on the detected signal bandwidth.

A power amplifier with supply switching is provided. The power amplifier detects a magnitude of an outgoing broadband communication signal and determines whether the magnitude exceeds a predetermined voltage threshold. The power amplifier applies a first gain to the outgoing broadband communication signal using a first voltage supply rail when it is determined that the magnitude exceeds the predetermined voltage threshold and a second gain using a second voltage supply rail that is smaller than the first voltage supply rail when it is determined that the magnitude does not exceed the predetermined voltage threshold. The power amplifier produces an output signal from the outgoing broadband communication signal with the applied first gain or the applied second gain, wherein a current of the outgoing broadband communication signal is switched between the first voltage supply rail and the second voltage supply rail in response to the magnitude being detected.

In some embodiments, a method for processing an audio signal in an audio processing apparatus is disclosed. The method includes receiving an audio signal and a parameter, the parameter indicating a location of an auditory event boundary. An audio portion between consecutive auditory event boundaries constitutes an auditory event. The method further includes applying a modification to the audio signal based in part on an occurrence of the auditory event. The parameter may be generated by monitoring a characteristic of the audio signal and identifying a change in the characteristic.

In some embodiments, a method for processing an audio signal in an audio processing apparatus is disclosed. The method includes receiving an audio signal and a parameter, the parameter indicating a location of an auditory event boundary. An audio portion between consecutive auditory event boundaries constitutes an auditory event. The method further includes applying a modification to the audio signal based in part on an occurrence of the auditory event. The parameter may be generated by monitoring a characteristic of the audio signal and identifying a change in the characteristic.

Provided is a reconfigurable amplifier. The reconfigurable amplifier includes a gain circuit including a gain path configured to amplify an input signal, and a feed forward circuit including a feed forward path configured to receive the input signal and perform feed forward compensation on the input signal, and a first control circuit configured to perform the feed forward compensation in a first mode by activating the feed forward path, and deactivate the feed forward path in a second mode different from the first mode.

In a semiconductor device, a first variable gain amplifier and a second variable gain amplifier constitute a switched capacitor type variable gain amplifier. A selection switch switches connection among the first variable gain amplifier, the second variable gain amplifier, and a load circuit such that the first variable gain amplifier and the load circuit are connected to each other when an amplification factor of the first variable gain amplifier is a predetermined gain or less, and the second variable gain amplifier is connected between the first variable gain amplifier and the load circuit when the amplification factor of the first variable gain amplifier is larger than the predetermined gain.