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| Number | Title | Issue Date |
| 7418058 | Distortion compensating apparatus and method The present apparatus includes: distortion amount detector which detects the amount of distortion of an output signal of the amplifier; parameter holder; parameter corrector which corrects a parameter held in the parameter holder in such a manner that the distortion... | 08/26/2008 |
| 7382887 | Method and device for reducing high frequency error components of a multi-channel modulator A method and device for reducing error components of a multi-channel modulator. The method comprises the steps of inverting substantially half of the channels of a modulator, and reducing error components between said inverted channels and said non inverted channels... | 06/03/2008 |
| 7259630 | Elimination of peak clipping and improved efficiency for RF power amplifiers with a predistorter A predistorer configured for use with an RF power amplifier having an input loop configured to be coupled to the input of the RF power amplifier and peak control circuit. Such an input loop includes a look-up table containing predistortion values to be applied to an... | 08/21/2007 |
| 7251290 | Adaptive controller for linearization of transmitter A bank of complex gain elements is used to provide a step-wise approximation of an arbitrary complex-gain predistortion function for a nonlinear transmitter. The bank of gain elements is in an adaptive loop realizing adaptive control. The adaptive loop is closed bet... | 07/31/2007 |
| 7190103 | Matching circuit for megasonic transducer device A method and apparatus for matching impedance magnitude and impedance phase for an acoustic-wave transducer load and an RF power source. The acoustic-wave transducer load has a load impedance magnitude and phase. The RF power source has a source impedance magnitude ... | 03/13/2007 |
| 6952133 | Low-distortion differential circuit A differential feedback system that minimizes even order distortion of a differential circuit. The feedback system includes a feedback circuit for use with a differential circuit to reduce even-order distortion and dc offset of a difference output signal produced by... | 10/04/2005 |
| 6924711 | Multimode modulator employing a phase lock loop for wireless communications A phase-amplitude modulator for mobile communications employs a phase lock loop as an input to a nonlinear power amplifier providing phase information with amplitude information used to modulate the power amplifier output to synthesize phase-amplitude for the RF tra... | 08/02/2005 |
| 6907085 | Activation method of communications apparatus with a non-linear distortion compensation device First, a digital section constituting a linearizer is activated. Then, a feedback loop for updating a distortion compensation coefficient is opened. Then, the analog section on the antenna side is activated from an ADC, including a PA, etc., or a DAC. Then, both the... | 06/14/2005 |
| 6771708 | Nonlinear compensator A nonlinear compensator comprising a signal processing section, a distortion detecting section, and a distortion correcting section. The signal processing section detects the time difference and phase difference between two signals by calculating correlation, synchr... | 08/03/2004 |
| 6674335 | Blind linearization using cross-modulation An amplitude modulated source signal (102) is received, where this signal has a source frequency bandwidth and a source envelope. A dummy envelope is computed that would yield a constant if the dummy envelope and source envelope were to be combined. An am... | 01/06/2004 |
| 6400415 | System and method for predistorting signals to be amplified A system and method for predistorting a signal which is to be amplified by a non-linear amplifier. The system and method uses additional predistortion circuits to eliminate the predistortion caused by amplifier input circuits and amplifier output circuits... | 06/04/2002 |
| 6169463 | Quadrature modulator with set-and-forget carrier leakage compensation A quadrature modulator with set-and-forget carrier leakage compensation. The quadrature modulator comprises an in-phase and a quadrature branch. In the in-phase and quadrature branches, real-time digital signals are converted to analog signals, the analog... | 01/02/2001 |
| 5798674 | Band Limited AM modulator using linear power amplification A band limited Amplitude Shift Keyed (ASK) modulator employing linear modulation and an efficient Class C power amplifier. Band-limited operation is provided by filtering a digital baseband input signal prior to modulation. Closed loop feedback is employe... | 08/25/1998 |
| 5798854 | In-line predistorter for linearization of electronic and optical signals An electronic circuit provides a linear output from a nonlinear transmission device such as a laser. Second and higher order distortion of the nonlinear device is compensated by applying a predistorted signal equal in magnitude and opposite in sign to the... | 08/25/1998 |
| 5699383 | High-power linear amplification using periodically updated amplitude and phase correction values In a high-power transmitter, an input complex signal is multiplied in a complex multiplier by control signals. The output complex signal from the multiplier is converted to a high frequency signal and amplified by a power amplifier for transmission. The a... | 12/16/1997 |
| 5481389 | Postdistortion circuit for reducing distortion in an optical communications system A postdistortion network for a receiver at a receiver location in an optical transmission system is disclosed. The receiver converts an optical signal carried over an optical transmission link to an RF signal. The postdistortion network includes an input ... | 01/02/1996 |
| 5381109 | Pulse step modulator having faulted module detection and compensation A pulse step modulator (PSM) is presented herein for use in an AM transmitter. The modulator includes a plurality of unit step modules connected together in series with each module including a DC voltage source together with an associated actuatable switc... | 01/10/1995 |
| 5339054 | Modulated signal transmission system compensated for nonlinear and linear distortion In a modulated signal transmission system operable in response to an input digital signal of a baseband to produce a modulated signal through a nonlinear amplifier, a nonlinear converter is controlled by a control signal generator to compensate for not on... | 08/16/1994 |
| 5327279 | Apparatus for linearization of optic modulators using a feed-forward predistortion circuit A feed-forward predistortion circuit to provide improved linear response in optic modulators. The circuit includes a non-linear element, an amplifier/delay means and a power combiner. The non-linear element generates a first signal sin(X), where (X) is th... | 07/05/1994 |
| 5123031 | Control voltage generator in a transmitter arrangement for digitally modulated signals A control voltage generator in a transmitter arrangement for, e.g., QAM signals comprising a class C output amplifier (AMP). The control voltage generator (CVG) comprises a memory with a look up table (ROM), whereby the I,Q-signals (I,Q) of the modulating... | 06/16/1992 |
| 5107520 | Adaptive predistortion circuit for a digital transmission system An adaptive predistortion circuit for a digital transmission system includes a predistortion circuit (521, 522, 523) for predistorting the input data before they pass through a modulator (56) and then through an amplifier ... | 04/21/1992 |
| 5105446 | Digital method of correcting non-linearity in a transmission chain, and apparatus implementing the method The invention provide a digital method of correcting non-linearity in a transmission chain, in which the effects of amplifier non-linearities are compensated by applying predistortion in baseband prior to modulation, with the signal being processed digita... | 04/14/1992 |
| 5091919 | Transmitter arrangement for digitally modulated signals A radio transmitter arrangement for e.g. QAM signals comprising a class C output transistor amplifier (AMP). The control voltage generator (CVG) comprises a memory, whereby the I,Q-signals (I,Q) of the modulating signal (DM) address the control voltage ge... | 02/25/1992 |
| 5049832 | Amplifier linearization by adaptive predistortion A method of linearizing an amplifier to produce an amplified output sample va in response to a predistorted input sample vd derived from an input modulation sample vm, such that va .perspectiveto.Kvm,... | 09/17/1991 |
| 5028890 | Voltage driven microwave amplitude modulation system A microwave amplitude modulation system maintains constant amplitude attenuation at very high modulation rates over a broad range of microwave frequencies in response to voltage driving signals derived from modulation signals. In the system, the video inp... | 07/02/1991 |
| 4745368 | Switching amplifier A digitally operating switching amplifier for direct and alternating voltage that is suitable as a modulation amplifier for radio transmitters with anode modulation. The power portion of the amplifier consists of cascade-connected, controllable, peak curr... | 05/17/1988 |
| 4644565 | Superposed quadrature modulated baseband signal processor A signal processor for providing a continuous raised cosine output signal having no jitter or intersymbol-interference and with controllable main and side lobes. An NRZ input signal is converted to a double interval raised cosine pulse signal having an am... | 02/17/1987 |
| 4554514 | Predistortion circuit with feedback A predistortion circuit for a microwave power amplifier which exhibits phase and amplitude nonlinearities and has a small signal gain equal to a. The phase distortion circuit includes a 180° coupler, a first coupler for coupling a given fraction of the i... | 11/19/1985 |
| 4485359 | Amplitude modulator having substantially zero modulation distortion An improved substantially "zero distortion" four quadrant modulator of the type including a pair of differential elements respectively coupled to the Y input port terminals of the modulator and exhibiting nonlinear amplitude transfer functions, includes t... | 11/27/1984 |
| 4346479 | Compensation for transmission element nonlinearities in a radio relay transmission system In order to compensate for nonlinearities introduced by a transmission member in a radio relay transmission system by means of a distortion converter stage, the converter stage is supplied with an intermediate frequency signal modulated with the useful si... | 08/24/1982 |
