An instrumentation amplifier configured for providing high common mode rejection is described and includes an input differential stage configured to receive a differential input voltage and a folded cascode amplifying stage configured to receive output current mode signals provided from the input differential pair. A plurality of feedback networks is provided to improve the input stage. The amplifier may operate to provide an enhanced common mode rejection ratio of a single gain block in the instrumentation amplifier. In some examples, the circuitry may have a differential folded cascode amplifying stage which permits high precision and low distortion of amplified signals without degrading the common mode rejection ratio.

A predictive brownout prevention system may be configured to prevent brownout of an audio output signal. Particularly, the brownout prevention system may be configured to receive information indicative of an amplitude of the audio input signal, receive information indicative of a condition of the power supply, determine from the information indicative of an amplitude of the audio input signal and the information indicative of the condition of the power supply whether a brownout condition exists, and responsive to determining the brownout condition exists, generate the selectable attenuation signal to reduce an amplitude of the audio output signal such that the signal path attenuates the audio input signal or a derivative thereof in order to prevent brownout prior to propagation to the audio output of a portion of the audio input signal having the brownout condition.

A load-modulated balanced amplifier (LMBA) based on a variable cross-coupled pair (XCP) is provided. The LMBA includes an adaptive bias (ADB) circuit, a first balance terminal amplifier module, a second balance terminal amplifier module, a control terminal amplifier module, a first driver amplifier module, a second driver amplifier module, a third driver amplifier module, a variable XCP, a resistor R5, a resistor R6, a 90-degree differential coupler Q1, a 90-degree differential coupler Q2, and a 90-degree differential coupler Q3.

Brownout management for an audio amplification system. An audio amplification system includes audio volume control circuitry, audio sample interpolation circuitry, and brownout management circuitry. The brownout management circuitry includes brownout detection circuitry and brownout response circuitry. The brownout detection circuitry is configured to determine whether a voltage of a battery that powers the audio amplification system is below a brownout threshold, and to generate a brownout detection signal that indicates the voltage is below the brownout threshold. The brownout response circuitry is coupled to an audio output of the audio sample interpolation circuitry. The brownout response circuitry is configured to attenuate the audio samples output by the audio sample interpolation circuitry responsive to the brownout detection signal indicating that the voltage is below the brownout threshold.

Apparatus and methods for biasing of power amplifiers are disclosed. In one embodiment, a mobile device includes a transceiver that generates a radio frequency signal and a power amplifier enable signal, a power amplifier that provides amplification to the radio frequency signal and that is biased by a bias signal, and a bias circuit that receives the power amplifier enable signal and generates the bias signal. The bias circuit includes a gain correction circuit that generates a correction current in response to activation of the power amplifier enable signal, and a primary biasing circuit that generates the bias signal based on the correction current and the power amplifier enable signal.

Disclosed are a sound source output apparatus based on amplification power source control according to a volume level and an operating method thereof. The sound source output method according to the exemplary embodiment of the present disclosure includes a volume level sensing step of sensing a volume level; a control step of generating a voltage control signal by determining an amplification power voltage for an amplification operation based on the sensed volume level; a power applying step of applying the adjusted amplification power voltage based on the voltage control signal; an audio signal generating step of generating an audio signal by performing an amplifying operation of the sound signal which is converted based on the amplification power voltage; and an audio output step of outputting the audio signal.

A squelch detector is disclosed by the present application. By configuring the first to third bias current sources and a mirror ratio of the current mirror circuit, when an amplitude difference between first and second input signals is smaller or greater than a squelch threshold, flip of an output node in the squelch detector depends only on the squelch threshold and is independent of variations of process, voltage and temperature (PVT) parameters. Thus, the squelch detector can always provide reliable amplitude detection of input signals despite of possible variations of the PVT parameters.

An instrumentation amplifier configured for providing high common mode rejection is described and includes an input differential stage configured to receive a differential input voltage and a folded cascode amplifying stage configured to receive output current mode signals provided from the input differential pair. A plurality of feedback networks is provided to improve the input stage. The amplifier may operate to provide an enhanced common mode rejection ratio of a single gain block in the instrumentation amplifier. In some examples, the circuitry may have a differential folded cascode amplifying stage which permits high precision and low distortion of amplified signals without degrading the common mode rejection ratio.

A method of controlling an electronic device having a battery and a speaker is disclosed. The method includes receiving an audio data signal, monitoring a battery-related parameter of the battery, determining whether the monitored battery-related parameter traverses a threshold, and bit-shifting the audio data signal based on the monitored battery-related parameter traversing the threshold. Also disclosed is an attenuator circuit for an electronic device having a battery.

In a power amplifier module for performing slope control of a transmitting signal, a gain variation due to a variation in battery voltage is suppressed while suppressing an increase in circuit size. The power amplifier module includes: a first regulator for outputting a first voltage corresponding to a control voltage for controlling a signal level; a second regulator for outputting a second voltage that rises as a battery voltage drops; a first amplifier supplied with the first voltage as a power-supply voltage to amplify an input signal and output an amplified signal; and a second amplifier for amplifying the amplified signal, wherein the second amplifier includes a first amplification unit supplied with the second voltage as the power-supply voltage to amplify the amplified signal, and a second amplification unit supplied with the battery voltage as the power-supply voltage to amplify the amplified signal.