1612 results about "Intermodulation" patented technology

A method and apparatus for use in improving the linearity characteristics of MOSFET devices using an accumulated charge sink (ACS) are disclosed. The method and apparatus are adapted to remove, reduce, or otherwise control accumulated charge in SOI MOSFETs, thereby yielding improvements in FET performance characteristics. In one exemplary embodiment, a circuit having at least one SOI MOSFET is configured to operate in an accumulated charge regime. An accumulated charge sink, operatively coupled to the body of the SOI MOSFET, eliminates, removes or otherwise controls accumulated charge when the FET is operated in the accumulated charge regime, thereby reducing the nonlinearity of the parasitic off-state source-to-drain capacitance of the SOI MOSFET. In RF switch circuits implemented with the improved SOI MOSFET devices, harmonic and intermodulation distortion is reduced by removing or otherwise controlling the accumulated charge when the SOI MOSFET operates in an accumulated charge regime.

A transmitter is provided for simultaneously transmitting a plurality of signals in a plurality of directive beams to corresponding destination stations, each destination station located in a separate fan within a service area. The transmitter includes a plurality of beamformers, each beamformer receiving one of the signals to be transmitted to an associated fan, each of the beamformers having a plurality of outputs for each different signal to be transmitted. A plurality of Butler matrices each receive one of the plurality of outputs from the plurality of beamformers for each different signal to be transmitted, each Butler matrix having a plurality of outputs in phased relationship to one another, wherein each of the signals to be transmitted is simultaneously provided across the outputs of each Butler matrix in a phased relationship. An antenna is provided with an aperture within which a two-dimensional array of antenna elements are disposed, wherein equal fractions of adjacent antenna elements are connected to the outputs of each Butler matrix, and wherein each of the plurality of signals are simultaneously transmitted by the entire two-dimensional array of antenna elements. Each of the plurality of beamformers receives steering control signals for steering the direction of each beam within its respective fan.

A transmitter channel interference mitigation processing method for cancellation of intermodulation products are described. In one embodiment, a method comprising generating continuous and real time IMP cancellation signals (ICS) in the baseband digital signal set of the transmitter based on a transmitter signal set, combining digital IMP cancellation signals with a digital baseband transmitter signal set such that the digital cancellation signals, when converted to analog signals and transmitted as part of an analog transmitter signal set, are cancelled by and so cancel the IMPs generated by the non-linear components in the analog transmitter hardware, including digitally generating the IMP cancellation signals using a process based on a power series description of a non-linear process generating the IMPs, generating 3^rd order IMP cancellation signals by digitally multiplying two or three signals of the transmitter signal set to create 3^rd order IMP cancellation signals, generating 5^th order IMP cancellation signals by digitally multiplying two or three or five signals of the transmitter signal set to create 5^th order IMP cancellation signals, generating 7^th order IMP cancellation signals by digitally multiplying two or three or five or seven signals of the transmitter signal set to create 7^th order IMP cancellation signal, generating odd order IMP cancellation signals (ICS) by digitally multiplying an odd number of digital signals and combining multiplied digital signals with the transmitter baseband digital signals, creating IMP cancellation signals in the receiver, and cancelling one or both of active and passive IMPs generated in a transmitter path that fall within a receiver passband.

One embodiment of the present invention relates to an adaptive filtering apparatus comprising first and second real valued adaptive filters, respectively configured to receive an adaptive filter input signal based upon a transmission signal in a transmission path. The first real valued adaptive filter is configured to operate a real valued adaptive filter algorithm on the input signal to estimate a first intermodulation noise component (e.g., an in-phase component) in a desired signal and to cancel the estimated noise. The second real valued adaptive filter is configured to operate a real valued adaptive filter algorithm on the input signal to estimate a second intermodulation noise component (e.g., a quadrature phase component) in the desired signal and to cancel the estimated noise. Accordingly, each filter operates a real valued adaptive algorithm to cancel a noise component, thereby removing complex cross terms between the components from the adaptive filtering process.

A predistortion circuit for a microwave amplifier and more particularly to predistortion circuit configured as a Doherty amplifier. The predistortion circuit is adapted to be coupled to a downstream Doherty amplifier to precompensate for the gain compression and phase expansion of the downstream Doherty amplifier as the input power level is increased while simultaneously reducing the intermodulation (IM) distortion. In order to provide precompensation, the precompensation circuit is operated at bias level to provide gain expansion and phase compression to cancel out the gain compression and phase expansion of the downstream Doherty amplifier to provide a higher overall linear power added efficiency (PAE).

A power amplifier system and method for locating carrier frequencies across a frequency band, identifying the modulation format of each carrier, and locating and suppressing undesired intermodulation distortion (IMD) products generated by the power amplifier. The system includes an amplifier for amplifying RF carrier signals in a main signal path, a variable phase shifter and variable attenuator on a feed forward path, and a tunable receiver that digitizes a portion of the frequency band to baseband. The tunable receiver includes a tunable voltage controlled oscillator which provides an oscillating frequency to a mixer and is phase-locked to a highly stable reference oscillator. The mixer downconverts a desired RF based on the oscillating frequency to IF. A filter passes only a selected portion of the IF signals, and the filter has a passband sufficient to discern both narrowband and wideband carriers and their associated IMD products. Based on the locations of the carrier frequencies, a processing unit determines the IMD locations of the carrier frequencies, determines the IMD locations, and adjusts the variable phase shifter and variable attenuator on the feed forward path until the IMD products in the main signal path are suppressed below a desired threshold.

In phased array antennas, multiple signals that perform different functions, such as radar, electronic warfare (EW) and telecommunications, can each be simultaneously transmitted only through a different sub-aperture of the array. For maximum power and efficiency, the power amplifiers operate on one signal at a time. This patent provides the technique of forming a common waveform from multiple signals for transmission through a common aperture. To practically implement this technique in wideband operations, processes performing the required waveform-shaping and amplitude-to-phase-modulation are devised that can transmit the high-power diverse waveforms without serious intermodulations and spectral distortion through every element of the array.

A method and apparatus for use in improving linearity sensitivity of MOSFET devices having an accumulated charge sink (ACS) are disclosed. The method and apparatus are adapted to address degradation in second- and third-order intermodulation harmonic distortion at a desired range of operating voltage in devices employing an accumulated charge sink.

A transceiver (10) includes an RF transmitter (12) and an RF receiver (14) coupled together through a duplexer (30) or non-filtering multiport device (30′). Either device may leak significant portions (56, 58) of the transmit signal (20) into the receive signal (44), and may significantly distort the transmit signal (20). Distortion is compensated in the transmitter (12) through the use of a linear predistorter (68) that is adjusted in response to an RF feedback signal obtained from the antenna-side of the device. Transmit signal leakage is compensated in the receiver (14) by producing an RF cancellation signal (106) that, when combined with the receive signal (44) at RF at least partially cancels the transmit signal portions (56, 58) leaked into the receive signal (44). Residual leakage signal and intermodulation products thereof may be cancelled digitally.

A method is proposed that is used for terrestrial transmission of at least one digital signal, in particular a digital radio and/or TV broadcasting signal. In this method, the at least one digital signal, reduced in its data quantity by coding, is modulated, preferably by the OFDM method, and converted into the frequency position of at least one channel, adjacent to at least one occupied or unoccupied channel (30, 32) for transmitting an analog TV broadcasting signal, and is broadcast in this frequency position. The dynamic scope and the amplitude of the spectrum (41) of the at least one digital signal must undershoot a respectively predetermined value that is markedly less than the dynamic scope or amplitude of the video carrier of the spectrum (35, 36) of the analog TV broadcasting signal, so that there will be only slight intermodulation and cross modulation with other digital signals or with analog signals of other channels. The spectrum (41) of the at least one digital signal is transmitted, separated from at least one adjacent channel (30, 31) by a protective frequency margin (45). When a plurality of digital signals are transmitted in the at least one channel (31), the frequency ranges of at least two digital signals are transmitted, separated from one another by a protective frequency margin (50).

The present invention relates to a device for the location of passive intermodulation faults in a coaxial cable network. The test apparatus (100) according to one embodiment of the present invention utilises a pair of high-power, frequency-synthesised, unmodulated RF carriers v₁(t) (101) and v₂(t) (102) are generated inside the HPA module of the apparatus. The power and frequency of v₁(t) (101) and v₂(t) (102) can be independently set to a range of values, v₁(t), v₂(t) are combined inside the instrument and then applied to the input of the device under test (DUT). The PIM signals (107,108,109) generated in the DUT are combined to produce the primary PIM signal v_IM(t) (103). The apparatus also includes two receivers (110,111,112,113,114,115) for the detection of v_IM(t) 103 and v_REF(t) (104). These signals are downconverted to 455 kHz. The two 455 kHz waveforms are digitised with a dual- channel A/D converter (116,117) and the amplitude ratio and phase offset between the digitised waveforms are calculated and stored.

A linearizer reduces nonlinear intermodulation distortion in radio frequency and microwave systems by first directly generating in-phase and quadrature nonlinear intermodulation products of the system input. Controllable amounts of each phase are then added back into the system such that the vector sum of nonlinear intermodulation products at the output is reduced or eliminated by destructive interference, while the fundamentals are substantially unaffected. The quadrature distorted signals are generated with two lightly-biased and thus overdriven differential pairs having gain-determining degeneration impedances that are in quadrature with each other. The amount of each quadrature phase summed to the output is controlled with electronically tunable four-quadrant variable attenuators. The quadrature phasing enables rapidly convergent tuning to minimize distortion using conventional scalar spectral analysis. The advantages of a linearizer using rectangular vector coordinate system are significant.

Multi-mode-multi-band direct conversion receiver with complex I and Q channel interference mitigation processing for cancellation of intermodulation products are described. In one embodiment, a method comprising over sampling of the entire receiver passband to acquire the IMP source signals that can generate IMPs within the SOI, using these signals to generate a coherent complex I-Q channel estimates of the interference and (after phase and amplitude adjustment) using these estimates to cancel the SOI inband IMPs in the I and Q channels independently and simultaneously in near real time, generating estimates of 2^nd and 3^rd order IMP products, adjusting the phase and amplitude of the estimates and using the estimates to cancel the SOI inband IMPs on the I ad Q channels independently and simultaneously in real time or very near real time, sampling of the transmitter feed thru signal and blocking signals and computing the cross modulation products estimate and adjusting the phase and amplitude and using the estimate to cancel the SOI inband cross modulation products energy in real time or near real time in the I and Q channels of the receiver, using the cross modulation cancellation to cancel of the effects of the on chip transmitter feed thru to support building a single transceiver chip with full duplex operation with cancellation being done independently and simultaneously on the I and Q channels of the receiver, and creation of an estimate of the DC offset in the receiver and adjusting the amplitude of the DC offset in a near real time closed loop fashion to cancel the DC offset in the I and Q channels independently and simultaneously and adjusting the rate of update to match system parameters.

A system that incorporates aspects of the subject disclosure may perform operations including, for example, receiving, via an antenna, a signal generated by a communication device, detecting passive intermodulation interference in the signal, the interference generated by one or more transmitters unassociated with the communication device, and the interference determined from signal characteristics associated with a signaling protocol used by the one or more transmitters. Other embodiments are disclosed.

A soft-solid ear piece is formed to fit the typical human ear canal and will self form to fill the ear cavity by having an internal structure, endoskeleton, or bladder to expand to precisely fit the ear piece securely and comfortably in the ear canal. This self forming ear piece will enable ready-ware and custom molded hearing aids, hearing protectors, audio ear pieces, cell phone ear pieces and assistive listening devices to fit comfortably, securely, and free of acoustic feedback in the external ear canal. It creates an acoustic seal to optimally reduce peripheral leakage and intermodulation distortion delivering excellent acoustic performance while keeping environmental sounds blocked out.

A system that incorporates aspects of the subject disclosure may perform operations including, for example, receiving, via an antenna, a signal generated by a communication device, detecting passive intermodulation interference in the signal, the interference generated by one or more transmitters unassociated with the communication device, and the interference determined from signal characteristics associated with a signaling protocol used by the one or more transmitters. Other embodiments are disclosed.

A radio frequency (RF) switch using a field effect transistor has 2^nd order intermodulation distortion improved through use of a feed forward capacitor electrically connected between the gate and a voltage coupler connected between the source and drain of the FET. With a control voltage provided at the gate through a gate feed resistor for operation of the FET, the feed forward capacitor feeds an RF voltage from the drain terminal and the source terminal to the gate terminal through the gate feed resistor.

A dual-frequency coaxial earphone has a shared magnet, which is interposed between a top board of a outer yoke and an outer disk of a inner yoke, wherein the outer yoke and the inner yoke each has a different polarity. A low-frequency voice coil of a low-frequency speaker part extends axially into and between an annular wall of the outer yoke and the outer disk of the inner yoke. An inner sleeve of the inner yoke extends into a first central opening of the outer yoke. Therefore, a high frequency of the high-frequency speaker part can pass through the inner sleeve so as to energize a central diaphragm of the low-frequency speaker part and to form a same phase as, and to output frequency synchronously with, the low-frequency speaker part. As such, the problem of intermodulation of distortion for the high and low acoustic frequencies can be solved, and that dimension of the earphone can be minimized.