A method may include providing a power supply voltage to a power supply input of a power amplifier by a charge pump power supply having a select input for selecting an operating mode of the charge pump power supply, such that in a first operating mode, the power supply voltage is equal to a first voltage, and such that in a second operating mode the power supply voltage is equal to a fraction of the first voltage; wherein the power amplifier has an audio input for receiving an audio input signal, and an audio output for providing the output signal, and generates the output signal based on the audio input signal. The method may also include selecting an operating mode of the charge pump power supply based on a magnitude of the power supply voltage and a magnitude of the output signal, such that the charge pump power supply operated in the operating mode having the lowest power supply voltage in which a difference between a magnitude of the power supply voltage and a magnitude of the output signal is more than the predetermined threshold voltage.

A communication device system includes a communication device (1) and a reception power monitoring device (2). The communication device (1) includes a reception processing unit (10) that outputs a signal intensity voltage (Vin) in accordance with a signal level of a received signal, and a monitoring terminal signal generator circuit (30) that generates a monitoring terminal signal (Vout) by current amplification of a level shift voltage generated by shifting a level of the signal intensity voltage (Vin) by an offset voltage (Voff) corresponding to a voltage value of a power supply voltage of an external device. The reception power monitoring device (2) includes a constant voltage generator circuit that outputs a constant voltage from the monitoring terminal signal (Vout), and a voltage converter circuit that operates based on the constant voltage and outputs a display level indication signal reflecting a voltage level of the monitoring terminal signal (Vout).

Apparatus (301) for switchable attenuation of a differential input signal from a microphone includes positive and negative non-attenuating paths (406, 410) have n- and p-type MOSFETs (421, 422, 423, 424) in back-to-back configurations; positive and negative attenuating paths (405, 409) have n- and p-type MOSFETs (415, 416, 418, 419) in back-to-back configurations in combination with resistors; a gate driver (425) applies a drive signal of one polarity (QNEG) to gates of the n-type MOSFETs in the attenuating paths and the p-type MOSFETs in the non-attenuating paths, and a drive signal of opposite polarity (QPOS) to the gates of the p-type MOSFETs in the attenuating paths and the n-type MOSFETs in the non-attenuating paths; and the state of the MOSFETs depends on the drive signals at their gates, and thus the input signal may be routed via either the non-attenuating paths or the attenuating paths by controlling the drive signals.

[Problem to be solved] The disclosure is to improve the temperature dependence in a current sense amplifier.

[Solution] A current sense amplifier measures a voltage drop in a drive transistor LS to measure the current flowing through the drive transistor LS. The current sense amplifier includes: a preamplifier pre-amp, to which a voltage across the drive transistor LS is inputted, and which obtains a positive output and a negative output corresponding to a voltage difference of the inputted voltage across the drive transistor; and a switch sw, which connects the input end of a common mode voltage vcm and the negative output, the common mode voltage vcm serving as the operation reference of the preamplifier pre-amp. A change of the positive output caused by turning on/off the switch sw can be detected.

Processes and systems for producing glass fibers having regions devoid of glass using submerged combustion melters, including feeding a vitrifiable feed material into a feed inlet of a melting zone of a melter vessel, and heating the vitrifiable material with at least one burner directing combustion products of an oxidant and a first fuel into the melting zone under a level of the molten material in the zone. One or more of the burners is configured to impart heat and turbulence to the molten material, producing a turbulent molten material comprising a plurality of bubbles suspended in the molten material, the bubbles comprising at least some of the combustion products, and optionally other gas species introduced by the burners. The molten material and bubbles are drawn through a bushing fluidly connected to a forehearth to produce a glass fiber comprising a plurality of interior regions substantially devoid of glass.

An amplifier (Trc,Trp) uses a GaN HEMT. A diode linearizer (LNZ) and a variable attenuator (VATT) are connected in series to an input of the amplifier (Trc, Trp). A peak detector (DET) detects a peak value of a drain voltage of the amplifier (Trc,Trp). A controller (CTL) makes the diode linearizer (LNZ) function as a linearizer to reduce an attenuation amount of the variable attenuator (VATT) if the peak value exceeds a threshold.

Techniques for controlling the output of a power amplifier are disclosed. In one embodiment, the techniques may be realized as a system that includes a power amplifier and a controller coupled to the power amplifier to form a feedback loop. The power amplifier is enabled or disabled in response to a blanking signal. The controller includes an accumulator that stores an accumulated error of the feedback loop. The controller suspends operation of the accumulator when (1) a level of the input signal is below a first threshold for an amount of time that exceeds a second threshold, (2) the blanking signal indicates that the power amplifier is disabled, or (3) both. The controller resumes operation of the accumulator when (1) the level of the input signal is above the first threshold and (2) the blanking signal indicates that the power amplifier is enabled.

An audio system includes an amplifier, regulating circuitry, and a filter. The regulating circuitry generates an audio voltage threshold signal based on an estimated value of the supply voltage source of the system, the estimated ESR between the system voltage supply and amplifier voltage supply pin, and the measured output resistance of the system. From these measurements/estimates, an anti-clipping voltage limit signal is generated. Power-budget-based and current-budget-based voltage limit signals are also determined based on first and second functions of the estimated value of the voltage source, respectively. The minimum of these three voltage limit signals is selected as the audio voltage threshold signal. The measurements, estimates and calculations are performed on a periodic basis to continually update the audio voltage threshold signal and thus adaptively regulate the audio system. A de-emphasis filter in the audio signal path compensates for capacitive ripple of the voltage at the amplifier's voltage supply pin.

A circuit arrangement for limiting the gate current at a field effect transistor, FET, comprises a first FET and a DC supply network connected to a gate terminal of the first FET; wherein the supply network provides a voltage Vgg to the gate terminal of the first FET via a first connection comprising a high impedance resistor R1 and a second FET connected in series therewith and having a gate terminal; the second FET having an ON state at a gate-source voltage of 0 V and having its gate terminal also connected to the gate terminal of the first FET via a second connection in parallel with the resistor R1; wherein a voltage drop occurring across the resistor R1 results in increasing blocking of the second FET.

An attenuation circuit comprising: a connection-node for connecting to an RF connection; an isolation-capacitor connected in series between the connection-node and an internal-node; a first-bias-resistor connected in series between a first-control-node and the internal-node; a second-bias-resistor connected in series between the internal-node and a second-control-node; a first-attenuation-diode connected in series between the first-control-node and the internal-node, wherein the anode of the first-attenuation-diode is closest to the first-control-node; a second-attenuation-diode connected in series between the internal-node and the second-control-node, wherein the anode of the second-attenuation-diode is closest to the internal-node; a first-decoupling-capacitor connected in series between the first-control-node and the reference-node; and a second-decoupling-capacitor connected in series between the second-control-node and the reference-node.