A clamping circuit that may be used to provide efficient and effective voltage clamping in an RF front end. The clamping circuit comprises two series coupled signal path switches and a bypass switch coupled in parallel with the series coupled signal path switches. A diode is coupled from a point between the series coupled signal path switches to a reference potential. In addition, an output selection switch within an RF front end has integrated voltage clamping to more effectively clamp the output voltage from the RF front end. Additional output clamping circuits can be used at various places along a direct gain signal path, along an attenuated gain path and along a bypass path.

Equipment that can comfortably hear mixed large sound and small sound at the same time by earphones and headphones is achieved. Level of rise and fall of an input signal waveform is logarithmically compressed and output to limit wave height, and an output signal is taken out from a wave-height-limited signal by eliminating or attenuating harmonic distortion. A limiter 6 limits an amplitude of an input sound signal. The integrator 7 is connected to the output-side of the limiter 6 and logarithmically compresses rise or fall of an output signal waveform from the limiter 6.

A decoder for a wireless charging transmitter and a wireless charging transmitter using the same are provided in the present invention. In order to adapt the wide range of the received signal from the wireless charging receiver, which usually results in the error of the decode, the feedback circuit of the wireless charging transmitter is changed, so that the signal in a certain swing is amplified by an original gain, and the signal out of the certain swing is amplified by a limited gain. Therefore, the amplified signal is able to show the characteristic of the original received signal. Thus, the accuracy of decoding is increased.

A number of monolithic diode limiter semiconductor structures are described. The diode limiters can include a hybrid arrangement of diodes with different intrinsic regions, all formed over the same semiconductor substrate. In one example, a method of manufacture of a monolithic diode limiter includes providing an N-type semiconductor substrate, providing an intrinsic layer on the N-type semiconductor substrate, implanting a first P-type region to a first depth into the intrinsic layer, implanting a second P-type region to a second depth into the intrinsic layer, and forming at least one passive circuit element over the intrinsic layer. The method can also include forming an insulating layer on the intrinsic layer, forming a first opening in the insulating layer, and forming a second opening in the insulating layer. The method can also include implanting the first P-type region through the first opening and implanting the second P-type region through the second opening.

Programmable clamping methods and devices providing adjustable clamping powers to accommodate different applications and requirements are disclosed. The described devices can use switchable clamping circuits having different structures, body-controlled clamping circuits, or clamping circuits adjusting their input power levels using programmable resistive ladders. Examples of how the disclosed devices can be combined to improve design flexibility are also provided.

A near-field transmitter includes a power amplifier, a resonant network, an envelope detector, and an antenna tuning circuit. The power amplifier has an input for receiving a communication signal, and an output for providing a differential output signal. The resonant network is coupled to the output of the power amplifier and has a tunable reactive element tuned by a tuning signal. The envelope detector is coupled to the output of the power amplifier for providing an envelope signal in response to the differential output signal. The antenna tuning circuit is for adjusting the tuning signal in response to the envelope signal.

Preventing RF signal distortion and signal error producing memory events in a Radio Frequency (RF) power amplifier (RFPA). An element, disposed prior to the Radio Frequency (RF) power amplifier (RFPA) in a signal path of a RF signal input to the RFPA, may enforce a maximum allowable amplitude in a high PAPR instantaneous high peak of the RF signal. An element may also increase or supplement a bias of the Radio Frequency (RF) power amplifier (RFPA) when a high PAPR instantaneous high peak is detected in the RF signal prior to receipt by the RFPA. Additionally, a first element operable detects when an instantaneous output voltage of the Radio Frequency (RF) power amplifier (RFPA) is below a predetermined voltage, and in response, a second element supplies additional current to prevent the output voltage of the RFPA from falling below a predetermined threshold voltage.

Preventing RF signal distortion and signal error producing memory events in a Radio Frequency (RF) power amplifier (RFPA). An element, disposed prior to the Radio Frequency (RF) power amplifier (RFPA) in a signal path of a RF signal input to the RFPA, may enforce a maximum allowable amplitude in a high PAPR instantaneous high peak of the RF signal. An element may also increase or supplement a bias of the Radio Frequency (RF) power amplifier (RFPA) when a high PAPR instantaneous high peak is detected in the RF signal prior to receipt by the RFPA. Additionally, a first element operable detects when an instantaneous output voltage of the Radio Frequency (RF) power amplifier (RFPA) is below a predetermined voltage, and in response, a second element supplies additional current to prevent the output voltage of the RFPA from falling below a predetermined threshold voltage.

An overvoltage protection and gain bootstrap circuit of a power amplifier includes a power amplification transistor, and a diode reversely connected with a gate of the power amplification transistor. A negative electrode of the diode is connected with the gate of the power transistor, and a positive electrode of the diode is connected with a constant voltage source, such that a function of overvoltage protection and gain bootstrap of the circuit is realized by controlling a turn-on state of the diode. By adding a diode device to the circuit, gate-drain overvoltage protection for the power amplification transistor can be provided, and the gain of the amplifier can be improved before power compression, thereby improving linearity of the power amplifier. The structure of the circuit can be simple, with reduced occupied area hardware cost.

There is provided a to-be-protection circuit that is high in operation accuracy and that prevents overvoltage on a protected circuit. A protection circuit is configured to protect a to-be-protected circuit from overvoltage. The to-be-protected circuit is connected to an external output terminal. The protection circuit includes: a current path unit connected to the external output terminal and including at least one first element; a reference voltage generation unit which generates and outputs a reference voltage; and an amplifier circuit outputs a target voltage based on a difference between a first input voltage and a second input voltage. The amplifier circuit operates using the reference voltage as the first input voltage and using a feedback voltage based on the target voltage as the second input voltage, and outputs the target voltage to the current path unit. The reference voltage generation unit includes at least one second element having an operating characteristic corresponding to an operating characteristic of the at least one first element of the current path unit, and generates the reference voltage based on a voltage drop caused by the at least one second element.