One embodiment is an apparatus including a detector circuit electrically coupled between a signal source and a second circuit, the signal source generating a first signal, the detector circuit detecting a level of the first signal and generating a first control signal when the detected level of the first signal exceeds a first threshold value, and a clamping switch electrically coupled to receive the first control signal from the detector circuit, the clamping switch including a multi-terminal active device. The first control signal controls a state of the clamping switch such that the clamping switch clamps a level of a signal applied to the second circuit when the level of the first signal exceeds the first threshold value.

In a gain control device, a gain control voltage adjust circuit includes a time-constant circuit and outputs an adjusted gain control voltage depending on an adjustment signal and a control voltage generated by a differential amplifier upon input of the adjustment signal. An adjustment signal generation circuit outputs the adjustment signal during an adjustment signal output period. This period is a specified period before a first burst signal is output from a signal output unit and where a burst signal is not output from the signal output unit. The adjustment signal is to make the adjusted gain control voltage closer to a target voltage. The target voltage is a gain control voltage output from the gain control voltage adjust circuit and corresponding to a steady part of a second burst signal. The second burst signal is a burst signal output before the first burst signal.

The present disclosure relates to a power amplifier (PA) system provided in a semiconductor device and having feed forward gain control. The PA system comprises a transmit path and control circuitry. The transmit path is configured to amplify an input radio frequency (RF) signal and comprises a first tank circuit and a PA stage. The control circuitry is configured to detect a power level associated with the input RF signal and control a first bias signal provided to the PA stage based on a first function of the power level and control a quality factor (Q) of the first tank circuit based on a second function of the power level.

A method is disclosed for estimating a duration that an instance of subject matter-related content will remain relevant. An archive of data sources spanning a period of time is analyzed to identify past instances in time in which a subject matter was newsworthy, and the duration of each instance. On receiving an indication that a user is interested in a current instance of the subject matter, an estimated period of time that the current instance will be of interest to the user is may be determined based on the duration of the past instances. In some aspects, the archive may be a corpus of social media data compiled from a social network, with each data source including or representative of an interaction between users in the social network, and the current instance of the subject technology may include content provided to the user through a social stream.

One embodiment is an apparatus including a detector circuit electrically coupled between a signal source and a second circuit, the signal source generating a first signal, the detector circuit detecting a level of the first signal and generating a first control signal when the detected level of the first signal exceeds a first threshold value, and a clamping switch electrically coupled to receive the first control signal from the detector circuit, the clamping switch including a multi-terminal active device. The first control signal controls a state of the clamping switch such that the clamping switch clamps a level of a signal applied to the second circuit when the level of the first signal exceeds the first threshold value.

Amplifier having input power protection. In some embodiments, an amplifier circuit can include an input node and an output node, and an amplifier implemented between the input node and the output node. The amplifier circuit can further include a bias circuit configured to provide a bias signal to the amplifier. The amplifier circuit can further include a protection circuit configured to generate a detected voltage representative of a peak of a radio-frequency signal present at the input node. The protection circuit can be further configured to enable a protection mode when the detected voltage is greater than a first threshold value and to disable the protection mode when the detected voltage is less than a second threshold value that is less than the first threshold value.

An audio amplifier includes: a buck controller configured to control an output voltage at a first supply terminal, the output voltage selected from a set including a plurality of output voltages, where the output voltage takes a settling time to settle; a first audio bridge including: a class-AB driver stage coupled to the first supply terminal, and a delay insertion circuit configured to receive a processed digital stream and provide the processed digital stream to the class-AB driver stage a delay time after receiving the processed digital stream, where the delay time is based on the settling time; and an audio amplitude detector configured to detect a first peak amplitude in the first digital audio stream, where the buck controller is configured to select a lowest output voltage from the set that is higher than the first peak amplitude plus a headroom voltage.

Techniques are described for using valley detection for supply voltage modulation in power amplifier circuits. Embodiments operate in context of a power amplifier circuit configured to be driven by a supply voltage generated by a supply modulator and to receive an amplitude-modulated (AM) signal at its input. The output of the power amplifier circuit can be fed to a valley detector that can detect a valley level corresponding to the bottom of the envelope of the AM signal. The detected valley level can be fed back to the supply modulator and compared to a constant reference. In response to the comparison, the supply modulator can vary the supply voltage to the power amplifier circuit in a manner that effectively tracking the envelope of the power amplifier circuit's output signal, thereby effectively seeking a flat valley for the output signal's envelope.

One embodiment is an apparatus including a detector circuit electrically coupled between a signal source and a second circuit, the signal source generating a first signal, the detector circuit detecting a level of the first signal and generating a first control signal when the detected level of the first signal exceeds a first threshold value, and a clamping switch electrically coupled to receive the first control signal from the detector circuit, the clamping switch including a multi-terminal active device. The first control signal controls a state of the clamping switch such that the clamping switch clamps a level of a signal applied to the second circuit when the level of the first signal exceeds the first threshold value.

The electronic circuit having an input stage for pre-amplifying an electrical input signal of the electronic circuit provided by a transducer. The electronic circuit has an output stage for providing a microphone output signal by processing an output signal of the input stage. The electronic circuit has an adjustable output load arranged and configured for setting a current draw of the output stage. Additionally, the electronic circuit has a measurement circuit configured to capture the output signal of the input stage and an automatic control circuit configured to adjust the adjustable output load dependent on the captured output signal of the input stage.