A close-down pop reduction system and a method for close-down pop reduction in an audio amplifier assembly are disclosed. The switching power conversion system comprises a forward path having a compensator and a switching power stage and a signal path from an output of a comparator in the switching power stage to a sequence control unit. The signal path includes a close-down timing circuit configured to provide a timing signal. The sequence control unit is configured to eliminate the input signal, increase the switch frequency of the close-down pop reduction system and disable the switching power stage at a moment in time within a PWM pulse of the switching power stage. Hereby, it is e.g. possible to minimize the audible pop during close-down of audio amplifier assemblies.

A voltage clamping system includes: (a) a first electronic device connected to a first power source and having a signal output node, a voltage clamp high node, and a voltage clamp low node, wherein the voltage clamp high node and the voltage clamp low node are coupled to a second power source different than the first power source; and (b) a second electronic device powered by the second power source and having a signal input node coupled to the signal output node of the first electronic device. The signal output node of the first electronic device is passively clamped, with low distortion, approximately rail-to-rail with respect to the second power source such that the second electronic device is protected from damage due to excessive voltage levels.

An amplifier includes a differential amplification block suitable for receiving and amplifying a first differential input signal and a second differential input signal; an output block suitable for determining an output signal according to a state of amplified signals outputted from the differential amplification block; and an output range restriction block suitable for controlling an output range of the output signal outputted from the output block based on a maximum clamping signal and a minimum clamping signal.

A circuit for implementing a differential input receiver is described. The circuit comprises an input circuit having a first input node and a second input node configured to receive a differential input signal; a first output circuit having a first capacitor coupled between the first input node and a first output node and a second capacitor coupled between the second input node and a second output node, wherein the first output circuit generates an output signal at the first output and the second output when the input signal is in a first frequency range; and a second output circuit comprising an amplifier having a first amplifier input coupled to the first input node and a second amplifier input coupled to the second input node, wherein the second output circuit generates an output signal when the input signal is in a second frequency range which extends lower than the first frequency range. A method of implementing a differential input receiver is also described. The circuits and methods also allow for offset compensation.

Embodiments of amplifiers and electrodes for capacitive styluses are disclosed. The amplifiers detect an input signal from a capacitive touch sensor, such as a touchscreen or touchpad, amplify and invert the signal, and emit the amplified and inverted signal to cause the capacitive touch sensor to detect a touch. The electrode sets, or tips, pair a sensing electrode and an emitting electrode, shielded from each other to limit interference, in a fine-point non-deforming configuration that improves usability over existing stylus tips.

An RF amplifier comprising an input-transistor having an input-transistor-base terminal, an input-transistor-collector terminal and an input-transistor-emitter terminal; a degeneration-component connected between the input-transistor-emitter terminal and a ground terminal; and a protection-transistor having a protection-transistor-base terminal, a protection-transistor-collector terminal and a protection-transistor-emitter terminal. The input-transistor-base terminal is connected to the protection-transistor-emitter terminal, and the protection-transistor-base terminal is connected to the input-transistor-emitter.

Embodiments of amplifiers and electrodes for capacitive styluses are disclosed. The amplifiers detect an input signal from a capacitive touch sensor, such as a touchscreen or touchpad, amplify and invert the signal, and emit the amplified and inverted signal to cause the capacitive touch sensor to detect a touch. The electrode sets, or tips, pair a sensing electrode and an emitting electrode, shielded from each other to limit interference, in a fine-point non-deforming configuration that improves usability over existing stylus tips.

A first voltage dividing circuit receives an internal power supply voltage at an input node. A buffer has an input node connected to an output node of the first voltage dividing circuit. A second voltage dividing circuit receives a power supply voltage V.sub.CC at an input node. A voltage of the output node of the first voltage dividing circuit is a first reference voltage V.sub.FIL, and a voltage of the output node of the second voltage dividing circuit is a second reference voltage V.sub.FILP. A resistor Ro is connected between an output node of the buffer and the output node of the second voltage dividing circuit. The clamp circuit controls the voltage of the output node of the first voltage dividing circuit such that the second reference voltage does not exceed a limit voltage determined to be equal to or lower than the internal power supply voltage.

A substrate ground conductor made of a semiconductor is provided. A transistor is configured with a collector layer, a base layer, and an emitter layer laminated on a substrate. A clamp circuit is configured with a plurality of elements disposed on the substrate. The clamp circuit is connected between the collector layer and the ground conductor or between the base layer and the ground conductor. The plurality of elements of the clamp circuit include a diode circuit made of a plurality of diodes, and a resistance element connected in series to the diode circuit. The resistance element is configured with a part of an epitaxial layer formed on the substrate.

In an audio amplifier circuit, a power supply terminal receives a power supply voltage. A voltage source generates an internal power supply voltage obtained by multiplying the power supply voltage by a first gain and a bias voltage obtained by multiplying the power supply voltage by a second gain. An input gain circuit amplifies an analog audio signal with reference to the bias voltage. The input gain circuit has an input stage and a gain stage. A phase compensation capacitor is connected to the gain stage. A withstand voltage protection circuit clamps an output voltage of the gain stage to a predetermined clamp voltage.