Abstract: An scheme to provide local oscillator feedthrough offset cancellation to remove baseband and radio frequency coupled offsets. Two separate offset cancellation currents are injected at a driver which drives a baseband signal into a mixer to mix with a local oscillator signal. One offset cancellation current cancels a baseband local oscillator feedthrough offset, while the other offset cancellation current cancels a radio frequency local oscillator feedthrough offset.

Abstract: A transmitting apparatus, a transmitting method, a receiving apparatus, a receiving method, a transceiver, a communication apparatus and method, a recording medium, and a program in which high quality voice can be decoded. A cellular telephone outputs coded voice data and also supplies uncoded voice sample data to a switching center while a telephone call is not made. Based on voice data used for the previous calculation processing and newly input voice data, the switching center performs calculation processing for quality-improving data for improving the quality of voice to be output from a cellular telephone that receives the coded voice data. The switching center stores the optimal quality-improving data as a user information database in association with the cellular telephone. The cellular telephone decodes the coded voice data based on the optimal quality-improving data supplied from the switching center.

Abstract: A combined matching and harmonic rejection circuit with increased harmonic rejection provided by a split resonance for one or more of the capacitive or inductive elements of the circuit. At a fundamental frequency, the circuit comprises an inductive series arm with capacitive shunt arms. The capacitance of a shunt arm may be provided by two or more parallel paths, each having a capacitor and an inductor in series so that, in addition to providing the effective capacitance necessary for impedance matching at the fundamental frequency, two separate harmonics represented by the series resonances of the parallel paths are rejected. In this manner, an extra null in the circuit's stop-band may be achieved using the same number of shunt elements necessary to achieve impedance matching at the fundamental frequency.

Abstract: An indication is received to relocate leakage in a transmission signal to be transmitted. A frequency change associated with relocating the leakage in the transmission signal is obtained. The leakage in the transmission signal is relocated based at least in part on the frequency change.

Abstract: A time division duplexing (TDD) transmission/reception apparatus and method are provided. The TDD transmission/reception apparatus includes: a transmitter which generates a transmitted signal; an antenna which transmits the transmitted signal to an external device and receives a received signal from an external device; a receiver which restores source data by demodulating the received signal; and a polarized duplexer which has a first end connected to the transmitter and the receiver and a second end connected to the antenna and comprises an inclined surface, the inclined surface polarizing the transmitted signal and the received signal such that the directivity of the transmitted signal and the directivity of the received signal are perpendicular to each other.

Abstract: A system for compensating for in-phase and quadrature (I/Q) imbalances for multiple antenna systems (MAS) with multi-user (MU) transmissions (defined with the acronym MU-MAS), such as distributed-input distributed-output (DIDO) communication systems, comprising multicarrier modulation, such as orthogonal frequency division multiplexing (OFDM).

Abstract: A method and system is described wherein an information signals is gated at a frequency that is a sub-harmonic of the frequency of the desired output signal. In the modulation embodiments, the information signal is modulated as part of the up-conversion process. In a first modulation embodiment, one information signal is phase modulated onto the carrier signal as part of the up-conversion process. In a second modulation embodiment, two information signals are multiplied, and, as part of the up-conversion process, one signal is phase modulated onto the carrier and the other signal is amplitude modulated onto the carrier. In a third modulation embodiment, one information signal is phase modulated onto the “I” phase of the carrier signal as part of the up-conversion process and a second information signal is phase modulated onto the “Q” phase of the carrier as part of the up-conversion process.

Abstract: A mobile wireless communications device includes a housing and antenna supported by the housing. At least one circuit board is carried by the housing and has radio frequency (RF) circuitry operative with the antenna for receiving and transmitting RF signals through the antenna. A power amplifier is connected within a transmission line for amplifying RF signals to be transmitted over the transmission line to the antenna. An antenna switch is carried by the circuit board and connected to the antenna and RF circuitry. An RF shield surrounds the power amplifier and antenna switch isolates the power amplifier and antenna switch from the antenna and RF circuitry.

Abstract: Methods and apparatus are provided to enable a transceiver (200) or transmitter including a single PA line-up (210) to transmit signals having frequencies in two or more different frequency bands, and/or having two or more different modulation types, and/or having two or more different RF power levels. The single PA line-up includes at least one variable matching circuit (216) and a variable harmonic filter (240) to tune match and tune filter communication signals prior to transmission. The variable matching circuit and the variable harmonic filter each include at least one variable capacitive element (2160 and 2400) that switches ON/OFF depending on whether a low frequency signal or a high frequency signal is being transmitted. Each variable capacitive element includes separate direct current and radio frequency terminals to enable the single PA line-up to change signal modulation and/or RF power levels in addition to frequencies.

Abstract: A method and apparatus for frequency up-converting a baseband signal to radio frequency (RF) in two steps using the two quadrature components of a single local oscillator signal. In a first stage, the baseband signal is split into two parts in quadrature with each other and supplied to a quadrature mixer that mixes the one component of the baseband signal with the I component of a local oscillator signal at frequency FLO and separately mixes the other baseband component with the Q component of the same local oscillator to produce an intermediate frequency signal centered at the local oscillator frequency and comprising two components, namely, an I component and a Q component. In the second stage, the intermediate frequency signal is mixed with both components of the same local oscillator signal in a sub-harmonic mixer-to produce a radio frequency output signal having a frequency component at three times the local oscillator frequency minus the baseband frequency.

Abstract: A harmonic suppression mixer for down converting an RF signal to a complex I and Q baseband signal that uses a plurality of switching mixers each with a gain stage to produce a sinusoidal weighted sum of the mixer outputs. Odd harmonics output by each switching mixer is suppressed in the composite signal. A low skew local oscillator (LO) clock generator creates multiple LO phases and drives the mixers. The mixer can be used in low noise direct conversion RF tuners. The mixer is configurable by programming gain stage coefficient values to achieve a variable number of effective mixers used in combination. At low tuning frequencies, all available mixers are programmed with unique coefficients and driven by different LO clock phases to achieve maximum harmonic suppression. At high tuning frequencies, some mixers are paralleled and duplicate coefficients are programmed or mixers are disabled to reduce the number of effective mixers.

Abstract: An apparatus in one example comprises a differential amplifier and a differential mixer. The differential amplifier is configured to receive a multi-octave differential input signal and output an amplified multi-octave differential output signal. The differential amplifier is also configured to substantially reduce second order harmonic distortion of the amplified multi-octave differential output signal through common mode rejection. The differential mixer configured to multiply the amplified multi-octave differential output signal with a local oscillator input signal and output an up-converted sub-octave differential output signal. The multi-octave differential input signal and the up-converted sub-octave differential output signal comprise a substantially same bandwidth.

Abstract: A method and system is described wherein a signal with a lower frequency is up-converted to a higher frequency. In one embodiment, the higher frequency signal is used as a stable frequency and phase reference. In another embodiment, the invention is used as a transmitter. The up-conversion is accomplished by controlling a switch with an oscillating signal, the frequency of the oscillating signal being selected as a sub-harmonic of the desired output frequency. When the invention is being used as a frequency or phase reference, the oscillating signal is not modulated, and controls a switch that is connected to a bias signal. When the invention is being used in the frequency modulation (FM) or phase modulation (PM) implementations, the oscillating signal is modulated by an information signal before it causes the switch to gate the bias signal.

Abstract: A wireless system having high spectral purity output signals. The wireless system has a transmitter circuit for transmitting an output signal and a power amplifier for amplifying the output signal for wireless transmission via an antenna. Positioned in-line with the output signal between the transmitter circuit and the power amplifier is a harmonic trap configured for inhibiting harmonics within a predetermined frequency range generated by the power amplifier from leaking into the transmitter circuit. The harmonic trap can be implemented as a discrete device, or integrated within the transmitter circuit or integrated within the power amplifier. By inhibiting the harmonics from leaking into the transmitter circuit, degraded performance of the transmitter circuit is prevented.

Abstract: The invention relates to a method and an arrangement for reducing interference in a radio apparatus. The solution comprises a clock signal generator, an analog part and a controller arranged to measure interference arising from the harmonic frequencies of the clock signal on the given radio channel, and a controller for controlling the pulse width of the clock signal on the basis of the measurement.

Abstract: A radio frequency (“RF”) harmonic filter circuit as disclosed herein is fabricated using integrated passive device (“IPD”) technology. The RF harmonic filter circuit is configured to provide second, third, and fourth harmonic rejection while providing good input and output impedance matching. The RF harmonic filter circuit employs only one IPD loop inductance (preferably used for a second harmonic resonance circuit), which results in a significant die/package size reduction. The RF harmonic filter circuit also employs a combined circuit that performs input and/or output impedance matching and third harmonic rejection.

Abstract: An RFIC transmitter includes a digital transmit processing module, a digital to analog converter, a filter and gain module, an up-conversion module, a power amplifier, and a transmit signal strength module. The transmit signal strength module is coupled to generate a gain adjust signal based on a measure of transmit power of an outbound RF signal, wherein the transmit signal strength module provides the gain adjust signal to at least one of the digital transmitter processing module, the digital to analog converter, the filter and gain module, the up-conversion module, and the power amplifier.

Abstract: Mixing circuitry for quadrature processing in communication systems and related methods are disclosed. The weighted mixing circuitry allows for arbitrary dividers to be utilized in generating the mixing signals for quadrature processing and thereby provides a significant advantage over prior architectures where 90 degree offset I and Q mixing signals were needed for quadrature mixing.

Abstract: An improved directional coupler that significantly reduces the signal degradation problems associated with distortion caused by circuit elements used to measure the transmitted power. In a selected embodiment, the directional coupler of the present invention comprises a plurality of active elements, such as capacitors, that have values selected to ensure that the distortion created by circuit elements used to measure forward transmitted power. In an embodiment of the invention, capacitors have values selected to minimize in-band distortion signals at the fundamental carrier frequency of the transmitted signal and also at the second and third harmonics of the fundamental carrier frequency.

Abstract: The invention relates to a device for converting frequencies comprising a local oscillator of fixed frequency and a first mixer with two inputs and an output, a first input receiving the signal to be converted and a second input receiving the signal arising from the local oscillator. It further comprises a second mixer with two inputs and an output, a first input receiving the signal arising from the phase-shifted local oscillator and the second input receiving a dc signal whose value is dependent on the power of the residual spectral component at the output of an adder receiving as input the signals arising from the first and from the second mixer(s) and giving as output a transposed signal. The invention applies in particular in terminals operating in the Ka band.

Abstract: A device reduces the dynamic range of a signal at a first point along a signal processing direction in a transmitter of a communication system. The device includes an input to which an input signal is applied, a correction prediction device, a delay device, an addition device, and an output. The correction prediction device generates a predictive signal based on the input signal which represents the prediction of the signal at the first point, and generates a correction signal from the predictive signal. The delay device generates an input signal delayed by a delay from the input signal, the delay taking into consideration the processing time in the correction prediction device. The addition device subtracts the correction signal from the delayed input signal in order to generate a corrected signal. The output provides the corrected signal at a second point in front of the first point.

Abstract: The present invention is a method and device for reducing exposure to undesirable electromagnetic radiation. The device uses a target antenna to capture certain radiation from an active emission source, such as a cell phone when it is transmitting or a microwave oven when it is cooking. The target antenna is tuned to the frequencies of the undesirable radiation emitted from the emission source. The device converts the captured radiation into an electric current, and dissipates the collected current by spending it to operate a thermal, mechanical, or electrical device. In the preferred embodiment, the current is directed to an LED display that lights up when supplied with the current, serving a secondary purpose of showing the user that the device is working.

Abstract: A power amplifier circuit (40) that includes an error correction loop (44) having a lower IP3 error correction amplifier (54) than a main power amplifier (46) in a main signal path (48). A first attenuator (52) in the error loop (44) attenuates the RF signal, and provides more attenuation of intermodulation products in the RF signal and about the same attenuation for a main frequency of the RF signal for each dB of attenuation. The error amplifier (54) amplifies the attenuated RF signal from the first attenuator (52). A second attenuator (56) in the error loop (44) attenuates the RF signal from the error correction amplifier (54). A phase shifter (58) phase shifts the RF signal from the second attenuator (56). A coupler (50) couples the amplified RF signal and the phase shifted RF signal to cancel out intermodulation products in the amplified RF signal.

Abstract: A technique for peak suppression, phase and amplitude equalizer of multi-carrier signals with different modulation is described. The input to the multi-carrier power amplifier is modified by a peak suppression, phase and amplitude equalizer circuit prior to being applied to the amplifier. The peak suppression is applied to a multi-carrier signal with different modulations and bandwidth. After peak suppression each individual carrier is phase and amplitude equalized to maintain the properties of the multi-carrier signal. The phase equalizer maintain the timing property of the carriers and the amplitude equalizer maintain the modulation accuracy of the individual carriers. The input to the peak-to-average reduction circuit could be a baseband, an intermediate frequency (IF) or radio frequency (RF) signal. The peak-to-average reduction is performed in digital domain.

Abstract: A tri-state chopper (TSC) circuit and method is disclosed. The tri-state chopper (TSC) circuit receives an input signal and a ternary signal and generates an output signal, wherein: the output signal tracks the input signal in both magnitude and sign when the ternary signal is in a first state; the output signal tracks the input signal in magnitude but has an opposite sign when the ternary signal is in a second state; and the output signal is set to zero when the ternary signal is in a third state.

Abstract: A polar modulator contains a phase locked loop which is designed to emit a radio-frequency signal at one frequency to one output, with the frequency being derived from the reference signal and from a phase modulation signal at a control input of the phase locked loop. The modulator additionally has a second signal input for supplying an amplitude modulation signal. The second signal input is connected to a control input of a pulse width modulator, one of whose signal inputs is coupled to the output of the phase locked loop. The pulse width modulator is designed to vary the duty ratio of a signal which is applied to the signal input, with this variation being adjustable via a regulation signal at the control input. A filter can be connected downstream from the output of the pulse width modulator and suppresses higher harmonic components in a signal which can be tapped off at the output of the pulse width modulator.

Abstract: A system or method for calibrating an RF transmitter includes inputting a test tone to the RF transmitter. LO leakage calibration is performed on an output of the RF transmitter with the test tone inputted thereto, in order to determine a minimum LO leakage. Thereafter, sideband image calibration is performed on the output of the RF transmitter with the test tone inputted thereto, in order to determine a minimum sideband image. Operational values for the RF transmitter are stored in memory based on the detected minimum LO leakage and the detected minimum sideband image, to be used during a normal operation mode of the RF transmitter.

Abstract: The participants of a friendly communication system use so-called time windows in the interference pattern for the communication and transmission among each other. These time windows are preset ahead of time in the communication system by the jamming transmitter or are created and/or adapted individually and short-term with the aid of software programs. Since only the communication-system participants can recognize and/or detect these time windows, they are the only ones that can receive and/or transmit corresponding information during these time windows. The information is compressed in the known manner, such that it can be transmitted and received completely during the brief time window provided. The information can then be decompressed and read during the time of interference in the known manner.

Abstract: Transmitting non-polluting dummy pilot signals in a wireless communication network permits estimation of the downlink propagation channels between a number of joint transmitters and a lesser number of receivers. With fewer receivers than transmitters, loop back information from the receivers is not sufficient to determine the downlink propagation channels between the transmitters and receivers. For N transmitters and M receivers, (N-M) dummy pilot symbols are transmitted to facilitate downlink channel estimation. Each dummy pilot signal is transmitted to an imagined or dummy receiver that is virtually located such that its downlink channel coefficient vector is orthogonal to those of the real receivers. Transmit pre-filtering based on estimated propagation channels is applied to the information signals for the real receivers and to the dummy pilot signals. The extent to which the dummy pilot signals interfere at each receiver is an indication of mismatch between estimated and actual propagation channels.

Abstract: A method of controlling noise in a pulse width modulation circuit includes varying a sample frequency and a range of information levels, wherein each sample within a data sample stream at the sample frequency represents a level within the range of information levels, to shift in frequency noise generated at the sample frequency during encoding of the data sample stream into pulse width modulated patterns.

Abstract: RF phase distortion circuits and methods for controllably phase distorting an RF signal based on amplitude of the RF signal. An MOS device is provided having a body of a first conductivity type and at least one region of a second conductivity type in the body, with a conductive layer over at least part of the body and the region of the second conductivity type and insulated therefrom. The MOS device may be coupled into a phase distortion circuit individually or in back-to-back pairs and biased to invert the body under the conductive layer for small signal amplitudes and not for large signal amplitudes, or to not invert the body under the conductive layer for small signal amplitudes and to invert the body under the conductive layer for large signal amplitudes. Various embodiments are disclosed.

Abstract: A method and a device for compensating a data-dependency of a power measurement caused by linear modulation is described. The method comprises performing a first measurement (160) of a transmitted output power and performing a second measurement (160) of a reflected power, wherein the second measurement is performed time multiplexed from said first measurement. The method further comprises calculating (171) a first average power based on data transmitted during the first measurement, calculating a second average power based on data transmitted during the second measurement, and compensating (171) at least one of the first measurement and second measurement based on a difference between the first average power and the second average power.

Abstract: The first, second, and third pairs of DC voltages which set a modulated signal to a predetermined reference level while the levels of I and Q signals supplied to a quadrature modulator are set at “0” are sequentially obtained. On the basis of the first, second, and third pairs of DC voltages, at least three measurement points based on a combination of pairs of DC voltages which set the level of the modulated signal to the predetermined reference level are decided. The coordinates of the center of a virtual circle having the three measurement points positioned on its circumference are automatically calculated by a geometric analytical computation. Adjustment voltages to be added to the I and Q signals so as to cancel out a carrier leak contained in the modulated signal are obtained from the coordinates of the center.

Abstract: A method and apparatus for noise cancellation in communications systems. The method is applicable in situations where an interfering signal or noise must be cancelled within a specified bandwidth. A sample of the interfering signal is used to synthesize a cancellation signal which is of equal amplitude but opposite phase to the original interference signal. Introduction of the cancellation signal into the interference signal path results in substantially complete suppression of the interference signal through vector subtraction of the superposed signal fields. Adaptive cancellation is also provided in that the frequency and bandwidth of the cancellation signal can be controlled. The adaptive nature of the cancellation loop also tracks out imbalances between the interference and cancellation signals caused by temperature variation and component tolerances. The adaptive nature of the cancellation system also allows the system to lock onto and track an interfering signal.

Abstract: A method and system is described wherein a signal with a lower frequency is up-converted to a higher frequency. In one embodiment, the higher frequency signal is used as a stable frequency and phase reference. In another embodiment, the invention is used as a transmitter. The up-conversion is accomplished by controlling a switch with an oscillating signal, the frequency of the oscillating signal being selected as a sub-harmonic of the desired output frequency. When the invention is being used as a frequency or phase reference, the oscillating signal is not modulated, and controls a switch that is connected to a bias signal. When the invention is being used in the frequency modulation (FM) or phase modulation (PM) implementations, the oscillating signal is modulated by an information signal before it causes the switch to gate the bias signal.

Abstract: A predistortion linearizer has signal dividing circuit dividing an input signal into two signals; signal adjusting circuit using one of the divided signals to execute predetermined adjustment and outputting a signal based on the adjustment; distortion signal generating circuit generating a distortion signal using the signal output from the signal adjusting circuit; signal synthesizing circuit synthesizing the other of the divided signals with the generated distortion signal; and signal amplifying circuit amplifying the synthesized signal and outputting an output signal, and wherein the signal adjusting circuit executes the predetermined adjustment such that there is a predetermined relationship between the level of a difference between the signal amplitudes of predetermined frequency components contained in a distortion signal and the level of a difference between the signal amplitudes of the predetermined frequency components contained in a distortion signal.

Abstract: A transceiver has frequency generating means for generating a first signal at a first frequency. The frequency generating means has first tank means for resonating at the first frequency. The transceiver further has frequency multiplication means for multiplying the first signal by an integral multiple of a fundamental frequency of the first signal. The frequency multiplication means has second tank means for resonating at a harmonic frequency of the fundamental frequency, the harmonic frequency being determined by the integral multiple. The frequency multiplication means has output means for outputting a second signal at the harmonic frequency. The first tank means is highly frequency selective around the first frequency, and the second tank means is highly frequency selective around the harmonic frequency. The transceiver has tuning means for simultaneously tuning the first and second tank means, and has up/down-conversion means for up/down-converting the second signal.

Abstract: A system handles both reception signals collected via an antenna and transmission signals generated by a communication station for transmission via the antenna. The system includes a cryostat, a receive path carrying the reception signals and disposed in the cryostat, and a transmit path carrying the transmission signals. The receive path and the transmit path are coupled between the system and the antenna and between the system and the communication station. Accordingly, the receive path is duplexed with the transmit path such that the front-end system has a first single input/output connection for coupling the front-end system to the antenna and a second single input/output connection for coupling the front-end system to the communication station.

Abstract: An improved method of predistorting a transmit signal is disclosed whereby the distortions occurring in all nonlinear subassemblies are compensated for using a particularly suited feedback signal. Also disclosed are a transmitter, a transmitting station, and a communications system using the method. The transmit signal, before being converted to the desired radio frequency, is digitally predistorted at baseband by digital signal processing means which are controlled by the feedback signal. This signal is generated by a detector measuring the spectral power of the transmit signal at the desired radio frequency both within a first frequency range, which lies within the transmission spectrum, and within a second frequency range, which lies outside the transmission spectrum. The digital predistortion disclosed is flexibly parameterized and is adapted by the feedback control to the current behavior of the transmitter subassemblies.

Abstract: A transmission circuit includes first and second amplifiers, a bandpass filter, a phase adjuster, and a signal combiner. The first and second amplifiers independently amplify input signals in different transmission frequency bands. The first amplifier in the ON state produces an unnecessary radiant wave in a frequency band substantially coinciding with the transmission frequency band of the second amplifier in the OFF state. The bandpass filter extracts a component in the same frequency band as that of an unnecessary radiant wave leaking out from the second amplifier during operation of the first amplifier. A phase adjuster adjusts the phase of an output signal from the bandpass filter such that the phase of the output signal from the bandpass filter becomes opposite to that of an unnecessary radiant wave in an output signal from the first amplifier. The signal combiner combines an output signal from the phase adjuster with the output signal from the first amplifier.

Abstract: A direct conversion transceiver capable of reducing a DC offset, using a multi-chip module is provided. In the transceiver, a mixer and an element constituting a local oscillator are positioned above a shielding ground surface, and an interconnection connecting the mixer and the element constituting the local oscillator are positioned below the shielding ground surface. The transceiver is formed as a multi-chip module and thus its size is not bigger than a one-chip direct conversion receiver and advantageous in that its size and manufacturing costs are less than a general direct conversion receiver that additionally includes a DC offset cancellation circuit or an off-chip type oscillator for reducing a DC offset.

Abstract: A solution for transmitting a plurality of carriers in a wireless system, such as GSM, TDMA, and WCDMA includes dividing a base-band digital input signal into two paths. In a reference path, an RF up-converter acts as a reference source for an analog FF error canceling loop having an RF bandwidth much wider than the required output (multiple carrier) bandwidth. The analog FF error loop also has an error-signal bandwidth that is wider than the error-signal bandwidth available from current ADC- and DAC-techniques. The other path feeds the base-band digital signal through another RF up-converter to an MPA in a FF MCPA and uses a digital predistortion technique to reduce distortion in the MPA, thereby easing the suppression demands on the analog FF error canceling loop in the MCPA. The difference (error) signal between the desired signal from the reference path and the actual MPA output signal is processed in an analog RF FF loop for canceling unwanted signals at the MCPA output.

Abstract: The present invention relates to a linearisation method and signal processing device for reducing intermodulation distortions by extracting harmonic components generated from first and second carrier signals with different carrier frequencies, which are input into two first non-linear stages (11, 12). The harmonic components may be generated by the two first non-linear stages (11, 12) or by two additional harmonic generating elements (NE1, NE2). The extracted harmonic components are phase and/or amplitude adjusted and mixed with harmonic components generated in a second non-linear stage (4) to thereby reduce harmonic components so as to achieve a linear output waveform. Thus, an intermodulation distortion suppression can be achieved over the entire operating bandwidth, wherein no phase coherency of the two carrier signals is required.

Abstract: A sinusoidal RF carrier is modulated for the transmission of digital binary data streams through the amplitude suppression of carrier wavelets. These wavelets are defined between zero crossover positions representing zero energy locations. This modulation is accomplished when the carrier is slightly amplitude modulated with a modulation signal that is equal in frequency to the carrier itself and the modulation always begins or ends upon the exact zero voltage crossing point of the RF cycle phase. The modulation is applied as a slight shift of the amplitude of any single cycle, each cycle representing a single bit of data. A single cycle of RF will either represent a “1” or “0” depending upon the amplitude of the cycle, relative to other adjacent cycles in the same carrier.

Abstract: A transmission power control apparatus for outputting a transmission data to be filtered by a band-limiting filter (9), includes: a branching unit (81) for branching transmission data before being entered into the band-limiting filter (9); a peak detecting filter (84) having the same structure as that of the band-limiting filter (9), for entering thereinto one of the transmission data branched by this branching unit (81); units (85 to 89) for calculating a correction value capable of suppressing a power peak of the transmission data by being filtered by this peak detecting filter (84); a delaying unit for delaying the other data of the branched transmission data by time required to calculate the correction value; and a correcting unit (83) for correcting the transmission data delayed by this delaying unit (82) based upon the correction value, and thereafter, for entering the corrected transmission data into the band-limiting filter (9).

Abstract: An RF transmission circuit, complex digital synthesizer and MRI apparatus are intended to enhance the stability of signal quantity and reduce the cost, wherein a complex digital synthesizer generates reference carrier frequency signal data directly in the digital domain, RF envelope mixers combine the resulting data and RF envelope signal data in the digital domain, and a digital frequency up-converter up-converts the resulting signal data in the digital domain and converts into an analog RF pulse signal.

Abstract: An apparatus and method for adaptively producing transmitted signals and processing received signals in a communication system which includes smart antenna array of antenna elements. When processing received signals, the invention modifies an existing processing scheme by incorporating information about a second set of signals for which training or other characteristic information such as a reference is unknown to information about a first set of signals for which characteristic information such as a reference is known, prior to executing the processing scheme. This approach can be used to modify the receive weights which determine the relative weight assigned to the signals received from each of a plurality of antenna elements to take into account the presence of a changing interference environment.

Abstract: An apparatus and method for canceling pilot signals from neighbor base stations is disclosed. The present invention cancels unnecessary pilot signals transmitted from the neighbor base stations by detecting, analyzing a PN signal in a pilot signal of each base station, generating estimated interference signal according to analyzed information from the detected PN signal and subtracting estimated interference signal from the received signal. Therefore, the present invention increases a bandwidth of downlink transmission channel and improves the demodulator to be operatable in low signal-to-noise ratio (Eb/No).

Abstract: The invention relates to a transmitter and a method of generating a transmission signal. A first modulation device 12 generates an uncompensated transmission signal Y(t) by modulating at least one baseband signal I, Q with a respective oscillation signal LOQ, LOI. The invention improves a transmitter with such a modulation device so as to reduce the expenditure for the filtering at a later stage that is necessary to attenuate undesirable components in the uncompensated transmission signal Y(t). This is achieved in that a compensation signal C(t) is formed on the output of a second modulation device (14), the compensation signal representing essentially the components to be compensated in the uncompensated transmission signal Y(t).

Abstract: The present invention relates to a harmonic circuit for improving linearity, the harmonic circuit according to the present invention comprises a first terminal connected to a collector of a NPN transistor and a second terminal connected to an emitter of the NPN transistor, and removes inter-modulation noise from the signal appeared at the collector of the NPN transistor. The harmonic circuit includes a PNP transistor, a first resistor, and a second resistor. The PNP transistor generates harmonic components without affecting the main signal, and the harmonic components that are generated by the PNP transistor compensate the harmonic components that are generated by the NPN transistor by having load of different sign from the load of the harmonic components that are generated by the NPN transistor.