Abstract: A printed circuit board includes a substrate, a signal output circuit formed on the substrate for outputting a clock signal, a shield for covering the signal output circuit, a power supply wiring for connecting the signal output circuit and a power source, and a trap filter provided to the power supply wiring and provided inside the shield, for attenuating a frequency component corresponding to a frequency of clock signal. The trap filter includes a resonance circuit having one portion of the power supply wiring, an inner-layer wiring of the substrate located below the one portion of the power supply wiring, an inner-layer ground wiring of the substrate located below the inner-layer wiring, and a via hole for connecting the one portion of the power supply wiring and the inner-layer wiring.

Abstract: Systems and methods are disclosed to process an optical signal using a pre-processor to populate a non-linearity compensation data structure based on a set of predetermined rules in a non-real-time off-line mode; and an amplifier applying said predetermined rules in real-time to one or more channel input data using the data structure to determine a non-linearity compensation output.

Abstract: A driver circuit includes a plurality of delay circuits and an inverter. The plurality of delay circuits delay branched driving signals. The inverter inverts at least one of the branched driving signals. At least one of the plurality of delay circuits is at least one variable delay circuit delaying a variable amount of delay. The output driving signal is output by combining the inverted signal of the branched driving signal output via at least one inverter and at least one non-inverted signal of the branched driving signals output from the delay circuits.

Abstract: An emphasis circuit includes: an applying circuit to add an emphasis signal to an input differential signal; a feedback path to feed back a differential output of the applying unit; a comparing circuit to compare a direct current component level of a positive phase signal and of a negative phase signal of the differential signal; a direct current component level controlling circuit to control a direct current component level of at least one of the positive phase signal and the negative phase signal; a delay unit circuit to add a delay to at least one of the fed-backed differential signal to generate the emphasis signal and inputs the emphasis signal into the applying unit; and a dummy load coupled to a positive phase signal output or a negative phase signal output of the applying unit.

Abstract: Disclosed is an optical system including a polychromatic optical source emitting multiple transverse modes, an optical link having at least one portion of multimode optical fiber, and an optical device positioned between the optical source and the input of the multimode optical fiber. The optical device can modify the distribution of the energy coupling of the transverse modes emitted by the source in the propagation modes of the multimode optical fiber. The optical system makes it possible to use low-cost transverse multimode optical sources for producing high-bandwidth Ethernet transmission networks having excellent performance.

Abstract: A method (10) of compensating phase noise in a coherent optical communications network. The method comprises: receiving a traffic sample (12); receiving an optical carrier and determining a phase noise estimate for the optical carrier (14); and removing the phase noise estimate from the traffic sample to form a phase noise compensated traffic sample (16).

Abstract: A distortion compensation circuit with frequency detection may be used with one or more non-linear elements, such as a laser, to compensate for frequency-dependent distortion generated by the non-linear element(s), for example, in broadband multichannel RF applications. Embodiments of the distortion compensation circuit may include a frequency detector circuit that detects changes in frequency loading conditions in the distortion compensation circuit such that distortion compensation may be adjusted to compensate for distortion under different frequency loading conditions. In a multichannel RF system with multiple channel operation modes, for example, the frequency detector circuit may detect changes in the frequency loading condition as a result of changing operation modes.

Abstract: Proposed is a light module (110) comprising at least two primary light sources (111,112,113) capable of emitting a primary color light. This allows the light module to emit light having intensity (Y) and color coordinates (x,y) through additive color mixing of the constituent primary colors. The light module further comprises an modulator (115) capable of modulating the primary light sources enabling embedment of data in the light emitted. The modulator (115) is arranged to modulate the color coordinates of the light emitted for embedding the data. This is especially advantageous as the sensitivity of the human eye to changes in color is lower than to changes in intensity. The invention thus advantageously allows embedding the data into the light emitted from the light modules (110) of an illumination system (100) without reducing the performance of its primary function as an aid to human vision.

Abstract: An optical phase conjugator that can be deployed within a long-haul fiber-optic link of an optical WDM system to improve the system's tolerance to intra- and inter-channel nonlinear effects. In one embodiment, the optical phase conjugator has a digital signal processor configured to perform, in the digital electrical domain, a phase-conjugation transformation for various components of a WDM signal so that certain signal distortions imposed on that signal in the front portion of the fiber-optic link are reduced in the back portion of the link. Advantageously, the optical phase conjugator is flexibly configurable to employ an input-to-output carrier-frequency-mapping configuration that is most beneficial under particular operating conditions. mapping configuration that is most beneficial under particular operating conditions.

Abstract: Embodiments of circuits and methods are described for decreasing transmitter waveform dispersion penalty (TWDP) in a transmitter. A data stream is received for transmission across a channel and a main data signal is generated from the data stream. At least two cursor signals are generated where each of the at least two cursor signals are shifted at least a portion of a clock period from the main data signal. The at least two cursor signals are subtracted from the main data signal to generate an output data signal with improved TWDP. Other embodiments include generating a main data signal, a pre-cursor signal shifted on previous clock cycle relative to the main data signal, and a post-cursor signal Shifted one subsequent clock cycle relative to the main data signal. The pre and post cursor signals are subtracted from the main data signal to generate an output data signal.

Abstract: Distortion and aliasing reduction for digital to analog conversion. Synthesis of one or more distortion terms made based on a digital signal (e.g., one or more digital codewords) is performed in accordance with digital to analog conversion. The one or more distortion terms may correspond to aliased higher-order harmonics, distortion, nonlinearities, clipping, etc. Such distortion terms may be known a priori, such as based upon particular characteristics of a given device, operational history, etc. Alternatively, such distortion terms may be determined based upon operation of a device and/or based upon an analog signal generated from the analog to conversion process. For example, frequency selective measurements made based on an analog signal generated from the digital to analog conversion may be used for determination of and/or adaptation of the one or more distortion terms. One or more DACs may be employed within various architectures operative to perform digital to analog conversion.

Abstract: Distortion and aliasing reduction for digital to analog conversion. Synthesis of one or more distortion terms made based on a digital signal (e.g., one or more digital codewords) is performed in accordance with digital to analog conversion. The one or more distortion terms may correspond to aliased higher-order harmonics, distortion, nonlinearities, clipping, etc. Such distortion terms may be known a priori, such as based upon particular characteristics of a given device, operational history, etc. Alternatively, such distortion terms may be determined based upon operation of a device and/or based upon an analog signal generated from the analog to conversion process. For example, frequency selective measurements made based on an analog signal generated from the digital to analog conversion may be used for determination of and/or adaptation of the one or more distortion terms. One or more DACs may be employed within various architectures operative to perform digital to analog conversion.

Abstract: A method for sending data to a memory chip includes receiving data at a data transmitter disposed on a memory hub chip, applying Tomlinson-Harashima precoding (THP) equalization to the data prior to transmitting the data; and transmitting the data from the transmitter to a memory chip.

Abstract: A forward error correction (FEC) communication device that includes a transmitter photonic integrated circuit (TxPIC) or a receiver photonic integrated circuit (RxPIC) and a FEC device for FEC coding at least one channel with a first error rate and at least one additional channel with a second error rate, wherein the first error rate is greater than the second error rate. The TxPIC chip is a monolithic multi-channel chip having an array of modulated sources integrated on the chip, each operating at a different wavelength, wherein at least one of the modulated sources is modulated with a respective FEC encoded signal. The TxPIC also includes an integrated wavelength selective combiner for combining the channels for transport over an optical link.

Abstract: A system and method with a modified bit-interleaved coded modulation with iterative decoding (BICM-ID). Coded and interleaved bits are combined and coded with a second FEC code that is then mapped to a modulation format. The second FEC code may be a single parity check (SPC) and the scheme may be referred to as a SPC-BICM-ID scheme.

Abstract: The present invention provides a nonlinear compensating apparatus and method and a transmitter. The nonlinear compensating apparatus includes: an information sequence acquiring unit, configured to acquire a symbol information sequence of the pulse signal; a perturbation quantity acquiring unit, configured to calculate, by pre-obtained weighting coefficients to which each item corresponds, the weighted sum of interaction items of pulses on one or more moments relative to the current moment; a perturbation quantity processing unit, configured to combine the items of the perturbation quantity based on the weighting coefficients; and an information compensating unit, configured to calculate a difference between the symbol information sequence and the processed perturbation quantity to obtain a compensated symbol information sequence. With the embodiments of the present invention, the complexity of calculation may be further lowered, and requirements on hardware may also be lowered.

Abstract: A method for communication includes modulating data to produce a series of symbols defined in a signal space. The symbols are pulse-shaped using a given pulse shape. A signal, which includes a sequence of the pulse-shaped symbols (104A . . . 104C) transmitted at a symbol rate that is higher than a Nyquist rate defined for the given pulse shape, is transmitted to a receiver (40). Prior to pulse-shaping the symbols, Inter-Symbol Interference (ISI) in the signal is pre-compensated for by applying a lattice precoding operation to the symbols. The lattice precoding operation confines the symbols to a predefined volume (110) in the signal space and is computed independently of any feedback from the receiver.

Abstract: Provided are an apparatus and method for compensating a feedback path distortion in a digital broadcasting signal. The apparatus for improving a performance of a pre-equalizer in a transmitter of a digital broadcasting system having a feedback path for adaptively generating a filter coefficient of the pre-equalizer, includes a reference signal generator for generating a reference radio frequency (RF) signal, a feedback path estimator for estimating transmission band characteristic information for the feedback path based on the reference RF signal generated from the reference signal generator, and a feedback path compensator for compensating a demodulated signal transferred through the feedback path based on the estimated transmission band characteristic information from the feedback path estimator and generating a filter coefficient of the pre-equalizer.

Abstract: A system for reducing peaks comprises a processor and a memory. The processor is configured to determine phase offsets for a plurality of input signals. The phase offsets are determined using trials of phase offsets to determine a selected set of phase offsets. The processor is further configured to modulate the input data signals using the selected set of phase offsets to produce modulated phase offset data signals and to generate a sum of modulated phase offset data signals, such that the sum has a lower peak value as compared to the sum not using the selected set of phase offset signals.

Abstract: In some embodiments, a method of reducing adjacent channel power ratio and compensating memory effects of multi-channel wideband communication systems using multiplexing modulation techniques is provided. The method includes generating an address from samples of a baseband input signal of a communication system. The method also includes retrieving from a memoryless lookup table an entry in accordance with the address. The method further includes pre-equalizing the baseband input signal, the pre-equalization depending on one or more magnitudes of the input signal. The method still further includes multiplying the pre-equalized baseband input signal and the lookup table entry.

Abstract: A system is operated to transmit signals from a transmitter to a receiver. The transmitter is muted. A receiver transfer function for the receiver is adjusted so that an output signal of the receiver is minimized. A transmitter transfer function of the transmitter is set to be inverse to the adjusted receiver transfer function.

Abstract: The present disclosure provides a multi-carrier optical transmitter, receiver, transceiver, and associated methods utilizing offset quadrature amplitude modulation thereby achieving significant increases in spectral efficiency, with negligible sensitivity penalties. In an exemplary embodiment, an optical transmitter includes circuitry configured to generate a plurality of optical subcarriers, a plurality of data signals for each of the plurality of subcarriers, and a plurality of modulator circuits for each of the plurality of subcarriers, wherein each of the plurality of modulator circuits includes circuitry configured to offset an in-phase component from a quadrature component of one of the plurality data signals by one-half baud period.

Abstract: Transmitter waveform dispersion penalty (“TWDP”) is decreased in a transmitter. A binary data signal is received for transmission over a channel that exhibits TWDP. The data signal is shifted less than a full clock cycle to generate at least one post cursor signal. The post cursor signal is subtracted from the data signal to generate a transmitter output data signal for transmission over the channel. In addition to decreasing TWDP, data dependent jitter is also reduced for data transmission across a channel that exhibits a multi-pole transmission characteristic. A main data signal and at least one cursor signal, which is shifted at least a portion of a clock period from the main data signal, is generated. The cursor signal is filtered to filter out effects based on the second pole of the multi-pole transmission characteristic. The main data signal is subtracted from the filtered cursor signal to generate the transmitter output data signal.

Abstract: A synchronous optical signal generation device includes: an optical phase detector that compares the phase of a reference optical signal with a phase of an optical beat signal to generate a phase error signal; a shaping mechanism that shapes the phase error signal; and a voltage controlled optical signal generator that generates an optical beat signal based on the shaped phase error signal and that outputs the optical beat signal while feeding the optical beat signal back to the phase detector.

Abstract: An optical transmitter includes: a pre-compensator calculating an electrical field of an optical signal subjected to an electronic pre-compensation with respect to an input digital signal; a parallelizer parallelizing the electrical field of the optical signal calculated by the pre-compensator; a plurality of optical modulators modulating an optical signal based on each of parallelized electrical fields of optical signals; and a time-division multiplexer time-division-multiplexing an optical signal output from the plurality of the optical modulators.

Abstract: A data transport card comprising an interface to receive high speed data streams from at least one client, and a pluggable conversion module which converts said data streams into optical data signals and couples these optical data signals into at least one wavelength division multiplexing channel for transport of said optical data signals via an optical fiber.

Abstract: A method includes delivering an electrical signal over an electrical conductor to a transmitter module, which includes a memory holding compensation values corresponding respectively to different conductor lengths. One or more of the compensation values is retrieved from the memory of the transmitter module, and a waveform of the electrical signal is modified responsively to the retrieved compensation values. The electrical signal having the modified waveform is transmitted using the transmitter module over a communication link.

Abstract: An optical communication system combines strong electrical pre-filtering of data at the transmitter and digital feedback equalization (DFE) at the receiver to enhance spectral efficiency. The system can be applied to optical networking and digital communication systems, including binary modulated systems optical network systems.

Abstract: An arrangement for providing pulse compression at the output of an optical continuum source (advantageously used in spectral slicing applications) includes a section of higher-order mode (HOM) fiber configured to exhibit a predetermined dispersion in at least a portion of the predetermined wavelength range and an effective area greater than 40 ?m2, the dispersion of the HOM fiber selected to compensate for the dispersion introduced by the optical continuum source. The HOM fiber generates a compressed pulse output therefrom. An input mode converter is used to convert the created continuum from the fundamental mode associated with the conventional continuum sources to the higher-order mode(s) supported by the HOM fiber used to perform pulse compression. A bandpass filter is used to limit the bandwidth of the continuum signal to that associated with both the efficient conversion range of the mode converter and desired dispersion characteristic of the HOM fiber.

Abstract: Distortion of a reception signal which is attributable to interference between subcarriers during photoelectric conversion is reduced in an optical OFDM communication system without broadening the signal band. A transmission signal processing unit (100) in a transmitter is provided with a distortion generating circuit (distortion generating unit) (170). A subcarrier signal is utilized as an input signal for the circuit. The distortion generating circuit (170) generates a baseband OFDM signal by means of inverse FFT calculation using the input signal, computes the square of the absolute value of the signal, and restores the subcarrier signal by mean of FFT calculation. Because interference between subcarriers is also included in the signal, the distortion element generated by the interference between the subcarriers can be extracted when the difference from the input signal is found.

Abstract: Provided is a multi-value optical transmitter in which a DC bias may be controlled to be stabilized so as to obtain stable optical transmission signal quality in multi-value modulation using a dual-electrode MZ modulator. The multi-value optical transmitter includes: D/A converters for performing D/A conversion on first and second modulation data which are set based on an input data series, so as to generate a first and a second multi-value signal, respectively; a dual-electrode MZ modulator including phase modulators for modulating light from a light source based on the first multi-value signal and the second multi-value signal, so as to combine optical signals from the phase modulators to output the optical multi-value signal; an optical output power monitor for detecting average power of the optical multi-value signal; and a DC bias control unit for controlling a DC bias for the dual-electrode MZ modulator, so as to maximize the average power.

Abstract: A system and method are provided for controlling the transmission of RF signals that are to be carried as optical signals over an optical fiber network. Operationally, the optical signals are transmitted as “bursts” in accordance with a standard protocol. For the present invention, transmission control requires an ON/OFF control that incorporates a time delay. Specifically, a “burst” of signals (RF/optical) is initiated when power in the RF input signal passes a predetermined threshold. After an established turn-on time that is set by the time delay, the ON/OFF control activates a laser diode for transmission of the “burst.” Further, the present invention provides control for constant optical output power from the laser diode. Importantly, the laser diode is OFF when a “burst” is not being transmitted.

Abstract: When a high data rate optical signal travels through a fiber link, its high frequency components tend to experience higher losses due to fiber dispersion (modal and/or chromatic). The loss of high frequency components causes the optical eye to close and the sensitivity to degrade. Disclosed is an apparatus and method for an optical transmitter that relies on anti-causal pre-emphasis to counteract the effect of relaxation oscillation, and therefore brings improvements to optical eye symmetry and mask margin (MM).

Abstract: A PDL compensation technique is provided that reduces the number of and the number of types of the PDL compensators even if it is uncertain to determine which of the two polarization principal axes of an optical device has a larger loss. The PDL compensator according to the present invention is configured to, before an optical signal input from a first or a second input/output terminal enters a PDL compensation device, switch between the first polarization principal axis and the second polarization principal axis of the optical signal depending on which of the first and the second polarization principal axes has a larger loss or gain.

Abstract: An example apparatus comprises an optical transmitter which includes a first processor and at least two optical modulators. The first processor is configured to generate a first electronic representation for each of at least two optical signals for carrying payload data modulated according to a one-dimensional (1-D) modulation format, and to induce on respective ones of the first electronic representations an amount of dispersion that depends on a power-weighted accumulated dispersion (ADPW) of a transmission link through which the at least two optical signals are to be transmitted thereby generating complex-valued electronic representations of pre-dispersion-compensated optical signals. Each of the at least two optical modulators modulate a respective analog version corresponding to a respective one of the complex-valued electronic representations onto a polarization of an optical carrier.

Abstract: An apparatus and method for generating a millimeter-wave carrier signal for optical data transmission is disclosed.

Abstract: A system includes a memory hub chip including a Tomlinson-Harashima precoding (THP) equalizer portion operative to perform transmitter equalization at the memory hub chip and send data from to a memory chip.

Abstract: Distortion and aliasing reduction for digital to analog conversion. Synthesis of one or more distortion terms made based on a digital signal (e.g., one or more digital codewords) is performed in accordance with digital to analog conversion. The one or more distortion terms may correspond to aliased higher-order harmonics, distortion, nonlinearities, clipping, etc. Such distortion terms may be known a priori, such as based upon particular characteristics of a given device, operational history, etc. Alternatively, such distortion terms may be determined based upon operation of a device and/or based upon an analog signal generated from the analog to conversion process. For example, frequency selective measurements made based on an analog signal generated from the digital to analog conversion may be used for determination of and/or adaptation of the one or more distortion terms. One or more DACs may be employed within various architectures operative to perform digital to analog conversion.

Abstract: Distortion and aliasing reduction for digital to analog conversion. Synthesis of one or more distortion terms made based on a digital signal (e.g., one or more digital codewords) is performed in accordance with digital to analog conversion. The one or more distortion terms may correspond to aliased higher-order harmonics, distortion, nonlinearities, clipping, etc. Such distortion terms may be known a priori, such as based upon particular characteristics of a given device, operational history, etc. Alternatively, such distortion terms may be determined based upon operation of a device and/or based upon an analog signal generated from the analog to conversion process. For example, frequency selective measurements made based on an analog signal generated from the digital to analog conversion may be used for determination of and/or adaptation of the one or more distortion terms. One or more DACs may be employed within various architectures operative to perform digital to analog conversion.

Abstract: An apparatus comprises an optical transmitter that comprises a processor and at least one optical modulator. The processor is configured to generate electronic representations of at least two pre-dispersion-compensated phase-conjugated optical variants carrying a same modulated payload data for transmission. The at least one optical modulator is configured to modulate the electronic representations, wherein an amount of dispersion induced on the pre-dispersion-compensated phase-conjugated optical variants depends on an accumulated dispersion (AD) of a transmission link through which the pre-dispersion-compensated phase-conjugated optical variants are to be transmitted. The amount of dispersion induced on the phase-conjugated optical variants may be approximately ?AD/2, where AD is the accumulated dispersion of the transmission link.

Abstract: In a method for transmission of digital data in an optical free-space transmission system in which a binary code sequence produced from the digital data is used to transmit amplitude-modulated light waves across an optical free space between a transmitter and a receiver, according to a first aspect, the binary code sequence is produced such that a modulation frequency of the light waves determined by the binary code sequence has a value of 70 Hertz. According to a second aspect, ‘t’ light waves are modulated with the binary code sequence and binary data are transmitted in blocks during a first time period, and non-modulated light waves are emitted during second time periods, wherein the light intensities of the time periods are selected so that the quantities of light transmitted in two periods correspond to predetermined quantities of light.

Abstract: Included are a first modulator, a second modulator, a first optical amplifier that amplifies an output of the first modulator at an amplification factor based on a first bias signal, a second optical amplifier that amplifies an output of the second modulator at an amplification factor based on a second bias signal, an optical phase adjuster that phase-rotates an output of the second optical amplifier, an optical multiplexer that multiplexes an output of the first optical amplifier with an output of the optical phase adjuster, and a second bias corrector that generates a first pulse signal and a second pulse signal, which are complementary to each other, and obtains a first bias value and a second bias value based on a change of strength of an output signal of the optical multiplexer. The first and second pulse signals are superimposed on the first and second bias signals, respectively.

Abstract: A method for limiting peak-to-average power of a signal transmitted from a power amplifier. The method comprises: applying a pulse-shape filter to a first signal, thereby generating a second signal being a filtered version of the first signal; and outputting the second signal for transmission from a power amplifier. The method further comprises: applying each of a plurality of predictor filters to a respective instance of the first signal, each predictor filter approximating the application of the pulse-shape filter to the first signal based on a different respective set of filter coefficients, and each thereby generating a respective third signal. The method also further comprises determining an indicator of amplitude of each of the third signals, selecting the indicator corresponding to the largest of those amplitudes, generating a modifier based on the selected indicator, and using the modifier to limit the first signal prior to applying the pulse-shape filter.

Abstract: An LD-Driver with a back termination circuit is disclosed. The back termination circuit of the invention provides a transistor as an active device, a current source to provide a bias current to the transistor, and a resistor as a passive element that couples the transmission lines carrying a differential signal thereon. Because the transistor shows a differential resistance of several tens of ohms by providing only a few milli-amperes, the output impedance of the LD-Driver may be substantially matched with the characteristic impedance of the transmission line with lesser additional power consumption.

Abstract: To reduce emission of an unintentional electromagnetic wave even if a frequency of a clock signal being output is high, a printed circuit board (10) includes: a substrate (101); signal output circuits (102 and 103) formed on the substrate (101), for outputting a clock signal; power supply wirings (109 and 110) for connecting the signal output circuits (102 and 103) and a power source; and trap filters (107 and 108) provided to the power supply wirings (109 and 110), for attenuating a frequency component corresponding to a frequency of the clock signal.

Abstract: A method of processing data is provided that includes receiving a plurality of binary electronic signals and generating an optical signal by a number of lasers that is equal to or greater than the number of binary electronic signals. The optical signal is generated at one of a plurality of intensity levels, and each intensity level represents a particular combination of bit values for the plurality of binary electronic signals. The optical signal is converted into an electronic signal having the plurality of intensity levels. An apparatus for processing data is provided that includes a plurality of lasers configured to emit light at a plurality of frequencies, and a plurality of modulators configured to receive a plurality of binary electronic signals and to modulate the light emitted by the lasers. An apparatus for transmitting data is provided that includes a photo receiver and an electronic signal generator.

Abstract: An improved precompensation circuit includes a greatly improved differentiator in the dispersion precompensation path, a preprocessor in the dispersion precompensation path for reducing f2?f1 type Composite Second Order (CSO) distortion, and a broadband phase shifter for compensating undesired vector interaction between the laser predistortion and dispersion compensation.

Abstract: A method for multiscale sampling for wide dynamic range electro-optic receivers is presented. The method comprises obtaining a signal, reproducing the signal into first and second signals, scaling one signal with respect to the other, modulating both signals with the same modulation function, and utilizing the resulting vector response function to invert the response of the link over a greater dynamic range than would otherwise be possible with a single instance of the modulated signal. The sealed modulation response may be obtained by splitting the signal into two polarizations and utilizing a modulator having different response for the two polarizations, or by utilizing two modulators.

Abstract: Fiber optic transmission technologies that allow DPSK or even higher order PSK to be performed at 20 gigabits per second per channel or even higher bit rates in a WDM (e.g., DWDM) wavelength multiplexed channeling environment. The technology employs pre-compensation of chromatic error dispersion such for each of most, if not all, channels have a portion of minimum absolute accumulated dispersion that occurs somewhere within the length (perhaps at the mid-point) of the optical channel. Post-compensation is then employed at the receiver to reduce or even potentially eliminate the chromatic dispersion. The technology allows for reduced bit error rates at high bit rates over even very long haul (e.g., trans-oceanic submarine or long terrestrial) optical fiber links, and for all channels.

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 envelope detector for finding the envelope 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 envelope 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 envelope voltage of the RF signal that are output to the quadrature modulator.