An amplifier circuit includes, a first transistor and a first resistor connected in series between a power supply voltage and an output terminal. A second transistor and a second resistor are connected in series between the output terminal and a ground reference voltage. There is a first operational amplifier and a second operational amplifier. A first detection current corresponding to a voltage drop across first resistor is generated. A second detection current corresponding to a voltage drop across the second resistor is generated. A first replication circuit subtracts the second detection current from the first detection current. A third resistor conducts the current obtained by subtracting the second detection current from the first detection current.

A logarithmic amplifier circuit includes an adaptive gain amplifier circuit and a transistor. The adaptive gain amplifier circuit includes a gain stage and a diode. The gain stage includes an input terminal, and an output terminal. The diode includes a cathode terminal coupled to the output terminal, and an anode terminal coupled to a common terminal. The transistor includes a first terminal coupled to the input terminal, a second terminal coupled to the common terminal, and a third terminal coupled to the output terminal.

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.

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).

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 wireless electric field power transmission system comprises: a transmitter comprising a transmitter antenna, the transmitter antenna comprising at least two conductors defining a volume therebetween; and at least one receiver, wherein the transmitter antenna transfers power wirelessly via electric field coupling when the at least one receiver is within the volume.

An amplification device includes an amplification stage having a transconductance amplification transistor and an output terminal. A biasing circuit is configured to bias in common mode the output terminal to a bias potential obtained on the basis of a voltage present between the gate and the source of the amplification transistor, and to compensate for parasitic variations of the voltage present between the gate and the source of the amplification transistor.

An amplification device includes an amplification stage having a transconductance amplification transistor and an output terminal. A biasing circuit is configured to bias in common mode the output terminal to a bias potential obtained on the basis of a voltage present between the gate and the source of the amplification transistor, and to compensate for parasitic variations of the voltage present between the gate and the source of the amplification transistor.

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.