A DC-DC converter according to an embodiment is a DC-DC converter for generating an output voltage VOUT according to a reference voltage VREF, and includes a fully differential amplifier that outputs a first differential output signal and a second differential output signal according to a differential input using the reference voltage VREF and the output voltage VOUT, a pulse width modulation signal generation circuit that generates a pulse width modulation signal based on the first differential output signal Vout1 and the second differential output signal Vout2, and a driver that outputs a driving signal obtained by waveform-shaping the pulse width modulation signal.

A device (100) for driving a self-conducting n-channel output stage field effect transistor (V1) comprising a control signal input (110), a control signal output (120) for connection to a gate electrode (V1G) of the output stage field effect transistor (V1), a first node (N1) connected to the control signal output (120), a second node (N2), and a first transistor (V4). A source electrode (V4S) of the first transistor (V4) is connected to the first node (N1), a gate electrode (V4G) of the first transistor (V4) is connected to the second node (N2) and a drain electrode (V4D) of the first transistor (V4) is either connected to the source electrode of the output field effect transistor (V1) or connected to a supply voltage (+Vdd). A resistor (R1) is connected with one end to the second node (N2). The device (100) is characterized in that the resistor (R1) is connected at the other end to the first node (N1). The first transistor (V4) can be used to cause the supply voltage (Vdd) to be applied to the control signal output when a low-level signal is applied to the control signal input (110).

An apparatus can include tracking circuitry coupled to a current source and configured to generate a reference voltage signal based on a reference current signal from the current source. The apparatus can include voltage regulator circuitry coupled to the tracking circuitry and configured to generate a voltage supply signal based on the reference voltage signal. The apparatus can further include amplifier circuitry configured to amplify an input signal based on the voltage supply signal. The reference voltage signal can track process and temperature variations associated with at least one field effect transistor within the tracking circuitry. The voltage regulator circuitry can be configured to operate with a closed loop gain higher than 1. The tracking circuitry includes a first transistor connected in parallel with a second transistor, the first and second transistors having a complimentary type with each other (e.g., NMOS and PMOS transistors).

In an embodiment, a class-AB amplifier includes: an output stage that includes a pair of half-bridges configured to be coupled to a load; and a current sensing circuit coupled to a first half-bridge of the pair of half-bridges. The current sensing circuit includes a resistive element and is configured to sense a load current flowing through the load by: mirroring a current flowing through a first transistor of the first half-bridge to generate a mirrored current, flowing the mirrored current through the resistive element, and sensing the load current based on a voltage of the resistive element.

The invention relates to a signal amplifier circuit for amplifying a signal, in particular an audio amplifier circuit, includes at least one first amplifier transistor (Q1) and at least one second amplifier transistor (Q2), wherein the first amplifier transistor (Q1) and the second amplifier transistor (Q2) are connected to one another in a push-pull circuit and are fed by an amplifier voltage source (V+, V); and one or more bias diodes (D1, D2) thermally coupled in each case to an associated amplifier transistor (Q1, Q2), wherein the bias diodes (D1, D2) are arranged in a parallel connection with respect to the amplifying transistors (Q1, Q2) to reduce or avoid a crossover distortion, wherein the bias diodes (D1, D2) are fed at least partly by a voltage source (UA) which is independent of the amplifier voltage source (V+, V). The invention furthermore relates to a system and a voltage converter for providing an output-side DC voltage, including a first transformer (T1) and a second transformer (T2) connected to the first transformer (T1).

A device (100) for driving a self-conducting n-channel output stage field effect transistor (V1) comprising a control signal input (110), a control signal output (120) for connection to a gate electrode (V1G) of the output stage field effect transistor (V1), a first node (N1) connected to the control signal output (120), a second node (N2), and a first transistor (V4). A source electrode (V4S) of the first transistor (V4) is connected to the first node (N1), a gate electrode (V4G) of the first transistor (V4) is connected to the second node (N2) and a drain electrode (V4D) of the first transistor (V4) is either connected to the source electrode of the output field effect transistor (V1) or connected to a supply voltage (+Vdd). A resistor (R1) is connected with one end to the second node (N2). The device (100) is characterized in that the resistor (R1) is connected at the other end to the first node (N1).

The first transistor (V4) can be used to cause the supply voltage (Vdd) to be applied to the control signal output when a low-level signal is applied to the control signal input (110).

A method for suppressing POP noise in an audio operation amplifier, comprising: connecting a first resistor and a second resistor in series at an output stage of the audio operation amplifier by turning on a first switch and a second switch; generating, with a ramp generator, a ramp voltage after an audio signal is input into the audio operation amplifier, wherein the ramp voltage varies from zero to a first value; generating, with an voltage generator, a second voltage, wherein a third switch is turned on and a fourth switch is turned off when the ramp voltage reaches the second value; short-circuiting the first and second resistors by turning off the first and second switches; and outputting, with the audio operation amplifier, an amplified audio signal.

A method for suppressing POP noise in an audio operation amplifier, comprising: connecting a first resistor and a second resistor in series at an output stage of the audio operation amplifier by turning on a first switch and a second switch; generating, with a ramp generator, a ramp voltage after an audio signal is input into the audio operation amplifier, wherein the ramp voltage varies from zero to a first value; generating, with an voltage generator, a second voltage, wherein a third switch is turned on and a fourth switch is turned off when the ramp voltage reaches the second value; short-circuiting the first and second resistors by turning off the first and second switches; and outputting, with the audio operation amplifier, an amplified audio signal.

An amplifier arrangement comprising first and second power amplifiers (T1, T2) having drains connected to positive and negative drive voltages, respectively, and gates connected to an input signal. The arrangement further comprises first and second current sensors (1, 2) for detecting first and second drain currents from the power amplifiers, processing circuitry (3) adapted to identify the smallest drain current, and a feedback control loop (5) and means for driving a bias current dependent on a feedback signal through a resistor connected between the input signal and the gate of an inactive one of the first and second power amplifiers. The control loop will keep the idle current constant in the transistor with the lowest current (the inactive transistor). Thereby, the current running in the transistor which does not deliver current to the load will be fixed at a desired value.

In an impedance converter using an electron tube as an active element, output impedance can be made sufficiently low, and the number of circuit elements therefor is decreased and a circuit configuration therefor is made simple. Provided is an impedance converter having an electron tube cathode-follower connected. The impedance converter includes a bias diode that provides a bias voltage to a cathode of the electron tube, high resistance elements that provide a voltage of the bias diode to a grid of the electron tube, a load circuit connected to the electron tube, and a complementary emitter output circuit including two transistors, respective bases of which are connected to one end and the other end of the bias diode.