Abstract: A device may include an envelope detector to generate an envelope signal from the input signal, a drain bias controller to adjust a drain bias of the amplifier based on the envelope signal, a gate bias controller to adjust a gate bias of the amplifier based on the envelope signal, a predistortion controller to predistort the input signal based on the envelope signal, based on the adjusted drain bias, and based on the adjusted gate bias, and to output the predistorted signal, and an amplifier to receive the predistorted signal and to generate an amplified output signal from the predistorted signal. The device may be selectable to operate in a linear mode or a nonlinear mode. The nonlinear mode may be selected by applying a large gate offset bias.

Abstract: A predistorter applies a distortion function to an input signal to predistort the input signal. The output of the distortion function is modeled as the sum of the output signals from the orthogonal basis functions weighted by corresponding weighting coefficients. Techniques are described for orthogonalizing the basis function output signals depending on the distribution of the input signal.

Abstract: Methods and circuits for pre-distorting a signal to compensate for distortion introduced by an electronic device operating on the signal. In an example method, first and second signal samples representing the input and output of the electronic device are generated. The first and second signal samples are spaced at unit-delay intervals, and each of the second signal samples corresponds in time to one of the first signal samples. Pre-distortion weights are then calculated from the first and second signal samples, the pre-distortion weights corresponding to a pre-distortion model comprising a lattice-predictor memory model structure having multiple delays and having at least one multi-unit delay interval between adjacent delays. The calculated pre-distortion weights are then applied to the input signal, using a predistorter with a structure corresponding to the lattice-predictor memory model, to produce a pre-distorted input signal for input to the electronic device.

Abstract: A wireless communication unit includes a linearised transmitter having a forward path and a feedback path, respectively comprising at least one up-mixer and down-mixer, and forming two loops in quadrature. A phase training signal is applied to the at least one down-mixer in the feedback path in an open loop mode of operation to identify a loop phase adjustment to be applied. At least one of the two loops is switched to a closed loop mode of operation and the loop phase adjustment is applied to at least one up-mixer located in the forward path.

Abstract: A method and an apparatus. The apparatus includes at least one sensor for sensing at least one parameter that affects a non-linearity of the non-linear amplifier and for generating at least one parameter indicator; a memory module for storing multiple sets of pre-distortion coefficient values; a retrieval module, coupled to the memory module, for receiving the at least one indicator, for selecting a selected set of pre-distortion coefficient values based on the at least one indicator, and for sending the selected set of pre-distortion coefficient values to a signal processing module; and a signal processing module, configured to receive an input signal, to receive the selected set of pre-distortion coefficient values, and to pre-distort the input signal, using the selected set of pre-distortion coefficient values such as to at least partly compensate for the non-linearity of the non-linear amplifier.

Abstract: A non-linear distortion signal contained in output signal components from a high-frequency power amplifier is detected, while a non-linear distortion signal is generated from a high-frequency signal to be amplified. Correlation between this non-linear distortion signal and the detected non-linear distortion signal is determined, and a control variable is calculated based on the signal thus obtained. The obtained control variable is multiplied by the generated non-linear distortion signal to generate a distortion compensation signal, which is added to the signal to be amplified. This provides a distortion compensation device capable of automatically maintaining optimum distortion compensation characteristics and rapidly achieving desirable distortion compensation.

Abstract: RF predistortion apparatus for making linear the output signal of non-linear components such as RF power amplifiers. The apparatus comprises an RF input line for carrying an RF signal connected to an envelop detector for finding the envelop of the RF signal, a power detector for finding the power of the RF signal and a quadrature modulator. The apparatus also comprises a coefficient vector input line for carrying an input signal that carries one or more coefficients to a digitally controlled analog subsystem (DCAS). The DCAS having circuitry for processing both the output of the envelop detector and the output of the power detector by selecting one or more coefficients from the coefficient vector input line for generating a weighted summation of the power of the RF signal and a weighted summation of the envelop voltage of the RF signal that are output to the quadrature modulator.

Abstract: A disclosed pop sound reduction circuit reducing generation of pop sound at activation or deactivation of an audio amplifier includes a reference voltage circuit generating a reference voltage, a differential amplifier circuit having first and second inputs to amplify the audio signal based on a comparison between the first and second inputs, a triangular voltage generator circuit generating a triangular voltage, a voltage current convertor circuit generating a current proportional to the triangular voltage, a capacitor charged with the generated current to generate a voltage corresponding to the generated current, a constant voltage circuit generating a constant voltage, and a control circuit switching the triangular voltage into the constant voltage to be applied to the voltage current convertor circuit so as to increase the generated voltage if the voltage generated by the capacitor is below the reference voltage when the triangular voltage is equal to or below a predetermined voltage.

Abstract: Coefficients of a pre-distorter are determined for correction of distortion of a signal amplified by a radio frequency amplifier by sampling the signal at the input to the pre-distorter to generate a plurality of input samples and sampling the signal at the output of the amplifier to generate a plurality of output samples, each of the plurality of output samples corresponding to one of the plurality of input samples, calculating a figure of merit for one or more of said plurality of input samples on the basis of the one or more of said plurality of input samples, selectively updating a previously selected set of input samples with said one or more of said plurality of input samples on the basis of the calculated figure of merit, whereby to generate an updated selected set and determining the coefficients of the pre-distorter on the basis of the input samples in the updated selected set and the corresponding output samples.

Abstract: A power amplifier apparatus that includes a processor that performs a first distortion compensation processing on an input signal using a distortion compensation coefficient to obtain a first signal and an amplifier that amplifies the first signal. The processor performs a second distortion compensation processing the amplified signal using the distortion compensation coefficient to obtain a second signal and updates the distortion compensation coefficient to enable convergence between the first signal and the second signal.

Abstract: An apparatus and method for linearizing a non-linear power amplifier. The method comprises: performing an iteration algorithm by using a desired output signal of the non-linear power amplifier, to calculate an input signal of the non-linear power amplifier, whereby with the calculated input signal of the non-linear power amplifier, the non-linear power amplifier is linearized. The apparatus and method can produce a signal on the output of the non-linear power amplifier with an arbitrarily high quality of performance.

Abstract: A transceiver includes a harmonic termination circuit that receives a tunable harmonic voltage from a power amplifier control. The harmonic termination circuit includes a variable capacitor that is capable of adjusting its capacitance in response to the tunable harmonic termination voltage to achieve at least two modes of operation. The at least two modes of operation may be EDGE mode and GSM mode. In this embodiment, the harmonic termination circuit allows for linearity specifications of EDGE to be met, while not degrading the efficiency of the transceiver when operating in GSM mode. In one embodiment, the harmonic termination circuit further includes an inductive element in series with the variable capacitor.

Abstract: Linearization circuits of the invention are used in conjunction with power amplification circuits that comprise a power amplifier core. Exemplary linearization circuits comprise a replica of the power amplifier core. In operation, the linearization produces an envelope signal from an RF signal. The envelope signal is used to control the replica to produce an analog output signal which represents the inverse of the AM to AM distortion of the power amplifier core. The linearization circuit then biases the RF signal with the inverted non-linear signal of the replica to control the power amplifier core. The power amplifier core and the replica thereof can be defined on the same semiconductor die so both respond to process variables similarly.

Abstract: A method and apparatus for a power amplifier module is described. The module includes a power amplifier and a power supply modulator coupled to the power amplifier. In addition, the module includes an inverter coupled between the power amplifier and the power supply modulator. The inverter provides a predistorted signal to the power amplifier to cancel distortion in the power amplifier provided by the power supply modulator. In addition, the module can include a driver coupled between the power amplifier and the inverter wherein the driver supplies the predistorted signal to the power amplifier.

Abstract: A transmission device includes an amplifier that amplifies a transmission signal according to a voltage to be applied, an envelope detector that detects an envelope signal of the transmission signal, a rate decreasing unit that decreases changing rate of the envelope signal detected by the envelope detector, and a voltage controller that changes the voltage applied to the amplifier according to the envelope signal whose changing rate is decreased by the rate decreasing unit.

Abstract: Disclosed is a method and apparatus for linearizing a power amplifier using a digital signal process (DSP), and particularly, is a method and apparatus for effectively linearizing an amplifier which has a plurality of distortion generating sources. To this end, there is a plurality of compensation methods and compensation units which can generate inverse distortion signals corresponding to the distortion components outputted by the plurality of distortion generating sources, thereby making it possible to provide superior linearity.

Abstract: Aspects of a method and system for power supply adjustment for polar modulation of an RF signal are provided. In an RF transmitter, a signal representative of an amplitude of a pair of phase-quadrature baseband signals may be generated, and a voltage and/or current supplied to one or more components of said RF transmitter may be controlled based on said generated signal. Additionally, aspects of the invention may enable dividing each signal of said pair of baseband signals by said generated signal, up-converting the divided signals, and combining the up-converted signals to generate a phase modulated RF signal. The one or more components may comprise, for example, one or more amplifiers, and/or one or more mixers. The generated signal may result from squaring each signal of the pair of baseband signals and calculating a square root of a sum of the squared signals.

Abstract: A wireless communications system includes a first multiplexer distribution network fed by a radio frequency input; a plurality of multi-stage power amplifiers fed by the first multiplexer distribution network, wherein each one of the multi-stage power amplifiers includes: a pre-distortion linearizer fed from the first distribution network; a first combiner receiving input from the pre-distortion linearizer; a second combiner; a plurality of power amplifier cells fed by the first combiner and feeding the second combiner; and a second multiplexer distribution network, wherein the second multiplexer distribution network is fed by the second combiner and feeds a radio frequency output.

Abstract: A system having: a digital pre-distortion circuit fed by a digital signal for distorting the digital signal; a digital to analog converter (DAC) core section coupled to an output of the calibration circuit for converting the distorted digital signal into a corresponding analog signal, the DAC core section performing the conversion in accordance with a control signal fed to the DAC core section; a power amplifier (PA) section coupled to an output of the DAC core section for amplifying power in the analog signal; and a calibration circuit coupled to the output of the power amplifier for producing, in response to the power in the power amplified analog signal, the control signal for the DAC core section.

Abstract: An embodiment of the invention discloses a power amplification device and method and a method for acquiring a power adjusting coefficient. The power amplification device according to one embodiment of the invention includes: a power control module configured to perform power adjusting on an input signal; a power amplification module configured to perform power amplification on the signal subjected to the power adjusting by the power control module; and a pre-distortion module configured to compensate for nonlinear characteristic of the power amplification module; wherein, said power control module is coupled between said pre-distortion module and said power amplification module in series; alternatively, said pre-distortion module is coupled between said power control module and said power amplification module in series. With the embodiment of the invention, a transmitter can be provided with a spectrum including a low side lobe even upon startup.

Abstract: A solid-state image sensor capable of suppressing color mixture while suppressing increase of load capacitances of transfer gates and a short circuit between two adjacent transfer gates is provided. This solid-state image sensor comprises a plurality of transfer gates and a shielding material line blocking light incident from above a prescribed pixel upon another pixel adjacent to the prescribed pixel. The shielding material line has a downward projecting portion on a region corresponding to at least one transfer gate entering an ON-state in photoreception.

Abstract: A transconductor for providing an output current that is linear in the input voltage (Vin) comprises a main output transconductor (Ms, Mc) and a model transconductor (Msr1, Msr2, Mcr1, Mcr2) that are controlled by the same signal (Vc, Vc?). The latter transconductor (Msr1, Msr2, Mcr1, Mcr2) is comprised in a predistortion circuit (A), which measures the output of the model transconductor and the overall voltage input (Vin) to provide a control signal (Vc, Vc?) for the transconductors that compensates for their non-linearity.

Abstract: A signal processing circuit includes a waveform shaping section that applies a first gain to an input signal and generates a first signal when an absolute value of a level of the input signal falls within a first input range from a first level to a second level, a variable gain section that adjusts an amplitude of the first signal and amplifies the first signal by a gain to generate an output signal, and a control section that reduces the gain of the variable gain section so that the output signal is prevented from occurrence of clipping when the amplitude of the first signal falls within a second input range. The second input range includes a range of the level of the first signal output from the waveform shaping section corresponding to the first input range of the input signal.

Abstract: An enhanced programmable automatic level control loop comprising an input for receiving an input RF signal; a level modulator, wherein the level modulator receives the input RF signal and a control signal and wherein the level modulator produces a first signal; a mixer that receives the first signal and mixes it with an LO signal to produce a second signal; a programmable attenuator that receives the second signal and produces an output signal; a level detector that monitors RF power of the output signal and produces a DC voltage proportional to the RF power; and wherein the DC voltage is received at a loop amplifier which produces the control signal.

Abstract: A system for processing an input signal, the system includes: a hardware memory module configured to store a lookup table; and a signal processing module, configured to process the input signal to provide a second signal, and to transmit the second signal to a power amplifier that is characterized by non-linearity and which is adapted to amplify the second signal to provide an amplified signal; wherein the signal processing module is configured to process the input signal in response to at least one filtering parameter to provide the second signal so as to at least partly compensate for the non-linearity of the amplifier; wherein the at least one filtering parameter is retrieved from the lookup table using a first, a second, and a third lookup table indexes, wherein the first index is responsive to a magnitude of the input signal at a first moment, the second index is responsive to a magnitude of the input signal at a second moment, and the third index is responsive to phases of the input signal at the first

Abstract: A transmission apparatus includes an analog digital converter that performs sampling on a demodulated signal obtained by demodulating a part of an output signal, which is produced by amplifying a modulated signal of a baseband signal including a plurality of signals having frequencies separated from each other, at a sampling frequency lower than a frequency of a given intermodulation distortion component and converting the demodulated signal into a digital signal, a detection section that detects an aliasing component of the given intermodulation distortion component produced by the conversion of the analog digital converter, and a distortion compensation section that compensates an input signal to be modulated for the given intermodulation distortion component in accordance with the detected aliasing component.

Abstract: Techniques to improve low noise amplifiers (LNAs) with noise canceling are described. LNA includes a first and a second amplifier which work together to noise cancel the noise generated at an input stage circuit. The input stage circuit receives an RF signal and is characterized by a first node and a second node. The first amplifier converts a noise voltage at the first node into a first noise current at an output of the first amplifier. The second amplifier is directly coupled to the output of the first amplifier and provides noise canceling by summing the first noise current with a second noise current generated by the second amplifier as a function of the noise voltage at the second node. The proposed techniques eliminate the need for large ac coupling capacitors and reduce the die size occupied by the LNA. The elimination of ac coupling capacitors between amplification stages of the LNA allows current reuse resulting in reduced current consumption.

Abstract: An amplifier system providing improved Cartesian feedback is provided. A complex band pass error amplifier is provided. A quadrature up converter is connected to the complex band pass error amplifier so as to receive as input, output from the complex band pass error amplifier. An amplifier is connected to the quadrature up converter so as to receive as input, output from the quadrature up converter. A quadrature down converter is connected at or beyond the amplifier output so as to receive as input a signal proportional to that delivered by the amplifier as output to a load, wherein the complex band pass error amplifier is connected to the quadrature down converter so as to receive as a first input, output from the quadrature down converter and as a second input, a quadrature reference signal.

Abstract: A method and system for digital spur cancellation may include removing a spur in a left channel minus right channel (L?R) baseband signal generated from a FM signal. The L?R baseband signal may be generated by demodulating a sub-carrier, for example, by using CORDIC algorithm, in a signal demodulated from the FM signal. An orthogonal signal may also be generated by demodulating a sub-carrier, for example, by using CORDIC algorithm, in a signal demodulated from the FM signal. The phase of the orthogonal signal may be further adjusted to introduce a substantially ?90° phase shift to spurs at a specific frequency. Accordingly, the spurs in the L?R baseband signal may be cancelled when the first L?R baseband signal is combined with the phase adjusted orthogonal signal.

Abstract: Disclosed are an apparatus and method for controlling output distortions of an amplifier. The apparatus for controlling output distortions of an amplifier, includes a compensation signal generator to predict a fluctuation of a supply voltage of a power supply using a prediction model which reflects fluctuations characteristics of the supply voltage, and to generate a compensation signal based on the prediction, and a compensator to transform an input signal using the compensating signal to control the output distortions.

Abstract: A digital predistortion circuit and method with extended operating range includes a predistortion function, a D/A converter, a multiplier for performing frequency translation and a power amplifier. The digital predistortion circuit includes a multiplier for receiving a signal to be transmitted and a gain correction factor, multiplying the gain correction factor with the signal to be transmitted, and outputting a result of the multiplication to the predistortion function, as well as a device for calculating the gain correction factor by using a predetermined reference gain and an estimated gain of the power amplifier, and outputting the calculated gain correction factor to the multiplier, whereby a gain of the power amplifier is quickly corrected. The digital predistortion circuit and the method thereof produce acceptable results for a more expanded range of TX power levels.

Abstract: A digital pre-distortion system which can provide the flexibility to model the highly non-linear distortion associated with High Efficiency RF Power Amplifiers while through a novel implementation of a least squares estimation process allows an implementation well suited for an FPGA application where limited resources and in particular memory resources are available.

Abstract: A distortion compensation apparatus and an apparatus and method for transmitting a signal are provided. The distortion compensation apparatus can extract precise distortion information by adding an additional signal to an input signal during the compensation of distortion in a nonlinear apparatus, and can linearize the nonlinear properties of the nonlinear apparatus using the distortion information. The apparatus for transmitting a signal can output a signal linearized by the same method as that used by the distortion compensation apparatus.

Abstract: A multi-carrier transmission device improves peak suppression efficiency in a multi-carrier signal. The multi-carrier transmission device (100) has a peak suppression unit (140) for dividing a multi-carrier signal into two parts: a first multi-carrier signal and a second multi-carrier signal. A peak signal detection unit (142) detects a power value at a predetermined interval concerning the first multi-carrier signal. When the detected power value is equal to or above a predetermined level, a peak extraction unit (144) extracts a signal component equal to or above the predetermined level from the first multi-carrier signal. A band limit filter unit (146) passes only a predetermined band from the extracted signal component. An adder (154) subtracts the signal component after the band limit from the second multi-carrier signal.

Abstract: There is disclosed a method for determining the timing misalignment between a power supply and an output in an envelope tracking amplification stage, the method including the steps of: estimating a distortion parameter in the amplification stage; and determining a timing error in dependence on the estimated distortion parameter.

Abstract: An apparatus and method to improve broadband amplifier linearization. The present circuits make use of pre-distortion techniques to improve the 3rd order distortion of an amplifier to reduce the amount of DC power required to achieve a given system requirement. In addition, the amplifiers have broadband characteristics which lend themselves to simplified pre-distortion. A pre-distortion linearizer circuit is connected across the input terminals of an amplifier. The linearizer circuit includes multiple diodes to improve the clipping performance of the linearizer. In addition, RC circuits align the phase of the linearizer distortion to be opposite that of the amplifier.

Abstract: A receive frequency band interference protection system includes an input terminal for receiving an input signal and a dividing coupler coupled to the input terminal. The dividing coupler is configured to divide the input signal into a first signal and a second signal. The system further includes a first signal path and a second signal path. The first signal path includes a delay, and it is coupled to the dividing coupler and configured to receive the first signal. The second signal path is coupled to the dividing coupler and configured to receive the second signal. The second signal path includes an attenuator coupled to the dividing coupler and a predistortion linearizer coupled to the attenuator. The system further includes a combining coupler and an output terminal. The combining coupler is coupled to the first signal path and the second signal path. The combining coupler is configured to obtain a sum of the respective outputs of the first signal path and the second signal path.

Abstract: A linearization device for a power amplifier using adaptive digital baseband predistortion includes a pre-inverse block receiving a complex discretized input signal {tilde over (x)}e(n) and restoring a complex predistorted signal {tilde over (x)}p(n) at the power amplifier input. The pre-inverse block includes a first module and a second module receiving the modulus of the complex input signal |{tilde over (x)}e(n)| at the input whose value is included in an amplitude domain varying between two values 0 and Amax, the amplitude domain being split into a plurality of segments, the first module associating with each value of the complex input signal modulus |{tilde over (x)}e(n)| contained in a given segment, a set of several parameters defining a model implemented in the second module via a function Fj, the second module restoring a value Fj(|{tilde over (x)}e(n)|), the complex predistorted signal resulting from multiplying the complex input signal {tilde over (x)}e (n) by the value Fj(|{tilde over (x)}e(n)|).

Abstract: A digital pre-distortion system which can provide the flexibility to model the highly non-linear distortion associated with High Efficiency RF Power Amplifiers while through a novel implementation of a least squares estimation process allows an implementation well suited for an FPGA application where limited resources and in particular memory resources are available.

Abstract: There is provided a distortion compensation apparatus for compensating distortion of an output of a power amplifier included in a radio transmitter. The distortion compensation apparatus includes a difference value calculator to calculate a difference value between a reference signal and a feedback signal, where the reference signal is branched from an input signal to the power amplifier and the feedback signal is branched from an output from the power amplifier; an integrator to accumulate the difference value; and a failure determiner to determine based on the accumulated difference value whether or not a failure has occurred or not.

Abstract: A method for determining pre-distortion of a power amplifier includes the following steps: providing a first power input signal to make the power amplifier generate a first power output signal; receiving a first receiving signal, which is acquired according to the first power output signal; detecting a predetermined gain of the power amplifier by means of the first power input signal and the first receiving signal; providing a second power input signal to make the power amplifier generate a second power output signal; receiving a second receiving signal, which is acquired according to the second power output signal; determining pre-distortion amplitude values and pre-distortion phase values of the power amplifier by means of the predetermined gain, the second power input signal and the second receiving signal.

Abstract: An amplitude-stabilized third-order predistortion circuit includes a main cell having a differential input for receiving a differential input voltage, a differential output for providing a differential output voltage, and a load control input for receiving a load control voltage; a plurality of replica cells having a differential input for receiving a differential level of peak input voltage, a differential peak output voltage, and a load control input; and a plurality of control circuits coupled to the differential outputs of the replica cells, and driving the load control inputs of the replica cells and the weighted inputs of a signal combiner driving the load control input of the main cell. The main cell and the replica cells each include a cross-coupled differential cell having a variable load.

Abstract: A variable equalizer apparatus for forward and/or reverse equalizers in an amplifier. The system can include a structure to allow continuous contact of the signal flow as an equalizer is removed; jumpers with fixed resistors and associated capacitors and inductors to produce a variable range over many different values; and/or variable resistance potentiometers with fixed resistors and associated capacitors and inductors to produce a variable range over separate value equalizers.

Abstract: An IQ-modulator pre-distorter includes an iteratively updated digital filter (gQ0, gQ1) for filtering one of the branches of an IQ-signal to compensate for IQ-modulator generated amplitude errors. An iteratively updated digital filter (cQI0, cQI1), cross-connected from one of the branches to the other branch, filters one of the components of an IQ-signal to compensate for IQ-modulator generated inter-modulation between the branches. Iteratively updated compensators (dcI, dcQ) counteract IQ-modulator generated offset errors.

Abstract: System and methods for reducing third harmonic distortion produced by nonlinear amplifiers are disclosed. A system may include an amplifier circuit with an amplifier transistor such that the amplifier is capable of exhibiting an amplifier output signal containing third harmonic distortion. Further, a system may include a nonlinear feedback circuit with a first feedback transistor operating in Triode mode that produces a feedback electronic signal containing a feedback third harmonic component. In addition, the nonlinear feedback circuit may be configured to the amplifier circuit in negative feedback such that the feedback third harmonic component of the feedback electronic signal reduces the third harmonic distortion of the amplifier output signal. A system may also provide an output signal that has less third harmonic distortion than the amplifier output signal.

Abstract: An embodiment of the invention uses a predistortion correction signal to combination the modulated RF signal by an analog multiplier for linearization of power amplifiers having nonlinear characteristics such as those used in wireless RF transmitters. A predistortion controller comprises a plurality of down converters for retrieving both the ideal non-distorted information and the feedback distorted information, together with pre-stored digitally-indexed predistortion information stored, for example, in a look-up table. The digitally-indexed information models nonlinear characteristics of the high power amplifier, and is stored prior to processing of pre-compensation in the power amplifier. When the predistortion information is combined with the modulated RF signal in the analog multiplier, the result is a substantially linear information transmission from the power amplifier.

Abstract: A feedforward distortion compensation amplifier includes an adjusting unit for adjusting a gain and a phase of an input signal, a first amplifier for amplifying a signal outputted from the adjusting unit, a delay unit for delaying the input signal, and a coupler for coupling a signal outputted from the delay unit to a signal outputted from the first amplifier. The feedforward distortion compensation amplifier further includes a first controller which detects a distortion component of the first amplifier to control an operation of the adjusting unit based on the distortion component, and a second controller which determines one distortion level from distortion levels based on a magnitude of the input signal, and compares the determined distortion level with the detected distortion component of the first amplifier to control an amplification rate of the first amplifier based on comparison results.

Abstract: A system for control of noise in a cable TV upstream path of a bi-directional cable TV home amplifier system that is positioned in the premises of the end user includes a noise control circuit and a coupler element that couples between the noise control circuit and the cable TV upstream path. The system further includes an amplifier part that is disposed on the upstream path. The noise control circuit connects or disconnects the cable TV upstream path depending on the level of signal passing through the cable TV upstream path. Namely, when the level of a signal that passes through the upstream path is lower than a predefined signal threshold, the noise control circuit disconnects the upstream path, and when the level of the signal is greater than a predefined signal threshold, the noise control circuit connects the upstream path.

Abstract: A digital pre-distortion system which can provide the flexibility to model the highly non-linear distortion associated with High Efficiency RF Power Amplifiers while through a novel implementation of a least squares estimation process allows an implementation well suited for an FPGA application where limited resources and in particular memory resources are available.

Abstract: A distortion compensation device includes a distortion compensation unit which compensates for a distortion generated in a power amplifier by using a polynomial in which a signal to be input into a power amplifier is raised to a power of a degree N (N is an integer larger than 0) and the raised signal is delayed by a delay number K (K is an integer larger than 0), and a polynomial adjusting unit which adjusts the degree N or the delay number K of the polynomial based on a comparison between a prescribed value, which indicates a degree of variation of the distortion generated in the power amplifier and a threshold value.