348 results about "Quadrature modulator" patented technology

A novel apparatus and method for a fully digital quadrature architecture for a complex modulator. The complex modulator can substitute for existing prior art analog quadrature modulator structures and those based on a digital polar architecture (r, θ). The modulator effectively operates as a complex digital-to-analog converter where the digital inputs are given in Cartesian form, namely I and Q representing the complex number I+jQ, while the output is a modulated RF signal having a corresponding amplitude and phase shift. The phase shift being with respect to a reference phase dictated by the local oscillator, which is also input to the converter / modulator. Several embodiments are provided including modulators incorporating dual I and Q transistor arrays, a single shared I / Q transistor array, modulators with single ended and differential outputs and modulators with single and dual polarity clock and I / Q data signals.

A millimeter wave pulsed radar system includes a radar synthesizer having a voltage controlled oscillator / phase locked loop (VCO / PLL) circuit, direct digital synthesizer (DDS) circuit and quadrature modulator circuit that are operative to generate an intermediate frequency local oscillator signal (IF / LO signal). A radar transceiver is operative with the radar synthesizer for receiving the IF / LO signal. A transmitter section has a frequency multiplier that multiplies the IF / LO signal up to a millimeter wave (MMW) radar signal and a receiver section and includes a direct conversion mixer that receives a MMW radar signal and the IF / LO signal to produce I / Q baseband signals that are later digitized and processed.

The present invention is related to methods and apparatus that compensate for quadrature impairments of an analog quadrature modulator and / or demodulator over a relatively wide signal bandwidth. One embodiment pre-distorts baseband signals in a quadrature modulator compensation signal processor (QMCSP) to negate the quadrature impairment of an analog quadrature modulator and corrects a received baseband signal in a quadrature demodulator compensation signal processor (QDCSP) to cancel the quadrature impairment of an analog quadrature demodulator. The QMCSP and the QDCSP contain adaptive digital filter correction structures that pre-compensate and post-compensate, respectively, for the quadrature impairments introduced by the analog quadrature modulator and the analog quadrature demodulator over a relatively wide bandwidth. A phase shifter advantageously shifts the phase of a local oscillator signal to the analog quadrature demodulator to distinguish quadrature impairments introduced by the modulation path from quadrature impairments introduced by the demodulation path.

An apparatus includes: an affine transformer that subjects input complex IF signals I(t) and Q(t) to affine transformation according to affine transformation coefficients, and outputs compensated signals a(t) and b(t); a quadrature modulator that applies quadrature modulation on a local oscillation signal according to the compensated signals, and outputs a modulated signal (RF transmission signal); a quadrature detector that removes a carrier component from the modulated signal and outputs complex feedback signals I′ (t) and Q′ (t); and a control portion that extracts linear distortions remaining in the complex feedback signals I′ (t) and Q′ (t) as plural distortion coefficients (DC offsets of the I-phase and the Q-phase, an IQ gain ratio, and a deviation in orthogonality), and updates the current affine transformation coefficients in accordance with updating equations including the distortion coefficients to set updated affine transformation coefficients again in the affine transformation portion. It is thus possible to constantly update the distortion compensation coefficients most appropriately under operating conditions.

Modulation Demodulation (Modem) Format Selectable (MFS) and Code Selectable (CS) systems for new generations of wireless systems, including third generation “3G”, spread spectrum systems, CDMA,W-CDMA and GSM, OFDM systems having different bit rates, that is having bit rate selection or bit rate agile( BRA) operation. MFS and Code Selectable (CS) systems connected to one or more modulators, one or more transmit amplifiers and one or more antennas. The transmitted signals are received by single or multiple receivers and demodulators.Shaped Time Constrained Signal(TCS) wavelet processors and bit rate agile Long Response (LR) filters provide shaped Time Constrained Signal (TCS) waveforms / filtered signals in in-phase(I) and quadrature-phase(Q) baseband channels to one or more Quadrature Modulators(QM) connected to the baseband signal processing network. A control processor and signal selection device selects one or more of the baseband signals and provides these signals through one or more quadrature modulators(QM) having the same or different radio frequency(RF) signals for amplification by one or more amplifiers. A selection device for selecting a Linearly and / or a Non-Linearly Amplified (NLA) modulated signal is provided and the selected amplified signal is provided to one or more transmit antenna systems or to one or more transmission media.

A transmitter chain has a quadrature modulator, a variable gain amplifier, an up-converter, and a variable gain power amplifier. An overall phase of the transmitter chain is adjusted on the basis of pre-stored phase information reflecting phase changes due to simultaneous gain changes of gains of at least the variable gain amplifier and the variable gain power amplifier.

A high-frequency transmission signal is transmitted from a transmission antenna with a predetermined transmission period, and a signal of a reflected wave reflected from a target is received by a reception antenna. A code generator generates a first code sequence and second code sequence that constitute a pair of complementary codes. A first modulator modulates the first code sequence to generate a first transmission signal. A second modulator modulates the second code sequence to generate a second transmission signal. A quadrature modulator performs quadrature modulation by using the generated first and second transmission signals. The high-frequency transmission signal is generated from a signal that is quadrature modulated, and transmitted from the transmission antenna.

An on-signal calibration system I and Q signals of a transmitter to remove distortions in the RF output signal. The transmitter generates I and Q values and converts, modulates and combines the I and Q values into the RF output signal for transmission. The calibration system includes a detector, a sampler, a selector, an imbalance estimator, and an IQ corrector. The detector senses the RF output signal and provides a detection signal indicative thereof. The sampler samples the detection signal and provides digital samples. The selector selects from among the digital samples that correspond to predetermined ranges of the I and Q values, or otherwise predetermined selection boxes at predetermined phases. The imbalance estimator determines at least one imbalance estimate based on selected digital samples. The IQ corrector corrects the I and Q values using at least one imbalance estimate.

In MIMO transmission which executes quadrature modulation of M transmission antennas and N reception antennas, a transmission signal vector will be set as a vector having the element number of 2M that comprises the in-phase components and quadrature components of M complex signals, a reception signal vector will be set as a vector having the element number of 2N that comprises the in-phase components and quadrature components of N complex signals, and a transfer matrix will be set as a real matrix comprising 2N rows and 2M columns. Then, a transfer matrix containing IQ mismatch is obtained based on a training signal, thereby executing MIMO encoding and decoding. For learning of the transfer matrix, a training signal which has two linearly-independent signal points on a constellation for each of the transmission antennas is used. With such arrangement, it is possible, in MIMO wireless data transmission, to compensate deterioration in a bit error rate that is caused by IQ mismatch in a quadrature modulator and a quadrature demodulator.

A quadrature modulator divides a part of a transmitted signal to generate a cancel signal. A signal comparator compares the amplitude and phase of the cancel signal which is generated by the quadrature modulator with those of a received signal, and outputs signals corresponding to the comparison results to the quadrature modulator. The quadrature modulator generates the cancel signal on the basis of the output signals of the signal comparator, and these components perform feedback control such that the cancel signal has the same amplitude as the leakage signal and is in phase with the leakage signal. A combiner combines the cancel signal with an antiphase cancel signal, which is made to be in opposite phase with the cancel signal outputted from the quadrature modulator, to cancel out the leakage signal.

The invention discloses a multi-channel nuclear magnetic resonance radio frequency signal transmitter which comprises a baseband signal modulation module, an orthometric up-conversion module and a radio frequency signal generation module, wherein the baseband signal modulation module comprises a field programmable gate array control module and a direct digital signal synthesizer; the orthometric up-conversion module comprises a power splitter, an orthometric modulator, a variable gain amplifier and the like; the radio frequency signal generation module supplies a local oscillation signal to the orthometric up-conversion module; and at least one baseband signal modulation module is arranged, and the orthometric up-conversion module is connected with the baseband signal modulation module and in the same number with the baseband signal modulation module. According to the multi-channel nuclear magnetic resonance radio frequency signal transmitter, the sole control and the parallel transmission of a plurality of paths of radio frequency signals are realized; all modulation functions are realized in a single-chip direct digital synthesizer (DDS), so that the integrated level of a system is improved; the radio frequency transmission of broadband can be carried out, and the full-range coverage of the signals is realized; and an orthogonal modulation system is adopted in the generation of the radio frequency signals, so that the mirror image frequency band is effectively suppressed, and the radio frequency power utilization rate is improved.

A quadrature demodulator 408′ and a quadrature modulator 908′ convert a reception intermediate frequency signal 151 into reception baseband signals 157 and 158, and also convert transmission baseband signals 657 and 658 into a transmission intermediate frequency signal 651, respectively. While local oscillation signals having frequencies suitable for the respective bands are outputted from a commonly used local oscillator 111, such a local oscillation signal obtained by shifting a phase thereof π / 2 by a phase shifter 412 is supplied to one mixer of quadrature mixers 109 and 609, and such a signal obtained by inverting, or not inverting the plurality of the local oscillation signal by an exclusive OR gate circuit 413 in response to a band switching signal 153 is supplied to the other mixer of quadrature mixers 110 and 610.

A system and method for compensating for the time delay between the in-phase I and the quadrature Q paths of a digitally modulated transmitter incorporating an analog quadrature modulator is disclosed. The time delay between the in-phase I and the quadrature Q paths is computed and used to calibrate a set of interpolation filters in the forward path that compensate for this delay, reducing the frequency dependent degradation in performance of the analog quadrature modulator. The disclosed system and method provides improved compensation of gain, phase and DC offsets in the analog quadrature modulator over a broader bandwidth. Fractional delay interpolation filters may be used to estimate the delay between the in-phase and quadrature paths. This eliminates the need for a factory calibration procedure, speeding up manufacture and reducing costs.

Systems and methods are described for a sideband suppression technique for quadrature modulation using magnitude measurements. Gain imbalance, phase imbalance, or both gain and phase imbalance are corrected in a quadrature modulator. Predetermined voltage levels are applied to one or both of the quadrature modulator input channels and resultant output magnitudes are measured. Then, a gain correction factor, a phase correction factor or both gain and a phase correction factors are determined as a function of the measured output magnitudes. Gain imbalance, phase imbalance or both gain and imbalance are then corrected using the gain and phase correction factors.

Quadrature modulation systems, circuits and methods are provided to support various modulation modes including ASK (amplitude shift key), FSK (frequency shift key) and PSK (phase shift key) modulation at high data rates (e.g., gigabit data rates). For example, a modulation circuit includes a mixer circuit including an integrated sign modulation control circuit and a plurality of mixer ports. The mixer ports include a first input port, a second input port, an output port and a sign modulation control port. The modulation circuit generates a modulated signal by operation of the mixer circuit multiplying a modulating signal applied to the first input port with a carrier signal applied to the second input port to generate a mixed signal output from the output port, and by operation of the integrated sign modulation control circuit controlling polarity switching of a signal at one of the mixer ports in response to a sign modulation control signal input to the sign modulation control port. The sign modulation control signal can be a digital data signal having binary data encoded into the modulated signal.

A transmission circuit includes a baseband circuit, spreading section, multiplier, digital modulator, quadrature modulator, and antenna. The baseband circuit generates and outputs at least one transmission data constituted by first and second channel data. The spreading section spreads the transmission data with a spreading code that differs for each transmission channel. The multiplier respectively weights the amplitudes of the first and second channel data by using a combination of two gain factors determined by a transmission data rate. The digital modulator digitally modulates the first and second channel data whose amplitudes are weighted by the multiplier. The quadrature modulator quadrature-modulates the digitally modulated first and second channel data and outputs the data as a transmission signal. The antenna emits the transmission signal output from the quadrature modulator as a radio wave. The multiplier weights the amplitudes of the first and second channel data by using gain factors that keep power of the transmission signal output from the quadrature modulator constant regardless of the transmission data rate without changing the ratio of a combination of gain factors determined by the transmission data rate.

A transceiver includes a transmitter, a receiver, and an electrical feedback line. The transmitter has a quadrature-modulator and is configurable to compensate inphase / quadrature phase imbalances produced by hardware of the transmitter. The quadrature-modulator is configured to quadrature-modulate a carrier wave. The receiver has a quadrature-demodulator and is configurable to compensate for inphase / quadrature phase imbalances produced by hardware in the receiver. The quadrature-demodulator is configured to demodulate a quadrature-demodulated carrier. The electrical feedback line connects an output of the transmitter to an input of the receiver.

A method and apparatus for direct-conversion transmission generates a first frequency signal that is non-harmonically related to a transmit frequency signal, divides the first frequency signal to obtain a mixing frequency signal, divides the first frequency signal to obtain an intermediate frequency reference signal, generates the transmit frequency signal by using the mixing frequency signal to downconvert the transmit frequency signal into an intermediate frequency feedback signal, and phase-locks the intermediate frequency feedback signal to the intermediate frequency reference signal. The transmit frequency signal may be phase modulated, and may serve as an input to a saturated-mode power amplifier that can be configured for corresponding amplitude modulation. Alternatively, the un-modulated transmit frequency signal serves as the carrier signal input to a quadrature modulator, which imparts I / Q modulations to it, thereby producing a modulated carrier signal for input to a linear power amplifier.

A phase signal is modulated in quadrature modulation by a quadrature modulator, and the frequency of this modulated phase signal is converted into carrier frequency by a frequency converter. An amplitude signal extracted from the modulating signal is delayed by a delay circuit, and an output gain signal designating the output average power gain is supplied to the output signal of the delay circuit. Synchronization of this frequency modulated phase signal and the amplitude signal delayed and added to the output gain signal allows to obtain an RF signal with little out of band undesired component even if the modulating signal contains amplitude variation. Therefore, the RF signal with little out of band undesired component is output even if the modulating signal contains amplitude variation.

In a jitter generator (phase modulator), worsening of phase noise is restrained and phase modulation accuracy is improved, and the phase modulation accuracy is improved by preventing a change in the detection sensitivity of the phase detector, if any, from affecting a change in the phase modulation index. Also, phase modulation is made possible without lowering the phase modulation accuracy even when an input phase signal increases. In a jitter generator using a PLL circuit, a quadrature modulator to which a modulation signal from a phase signal generator is provided is inserted to an input stage of a phase detector that constitutes the PLL circuit. In addition to this, an overflow detector that detects an overflow on an upper limit side or lower limit side of an analog / digital converter, a control unit that outputs a value for an effective region of the analog / digital converter on the basis of an output of the overflow detector, a digital / analog converter that coverts an output of the control unit to an analog signal, and an adder that adds an output of the digital / analog converter to the modulation signal, are provided.

The invention discloses an amplifier digital pre-distortion device based on a dynamic fuzzy neural network. The amplifier digital pre-distortion device comprises a digital pre-distortion device, a digital analog converter, a broadband quadrature modulator, a power amplifier, an attenuation coupler, a broadband quadrature demodulator, an analog digital converter and a pre-distortion device training module. Dynamic fuzzy neural network pre-distortion processing is conducted on an inputted digital baseband signal through the digital pre-distortion device, coupling, quadrature demodulation and analog digital conversion are conducted on an analog baseband signal outputted by the power amplifier through the attenuation coupler, the broadband quadrature demodulator, the analog digital converter respectively, and then an outputted digital baseband signal is generated. The inputted digital baseband signal and the outputted digital baseband signal are synchronously inputted into the pre-distortion device training module, and the pre-distortion device training module obtains a dynamic fuzzy neural network module parameter after carrying out parameter training through an online self-organized learning algorithm and sends the dynamic fuzzy neural network module parameter to the digital pre-distortion device. The invention further provides an amplifier digital pre-distortion method. By means of the amplifier digital pre-distortion device and method, the advantages of a fuzzy system and the advantages of a neural network are combined, dynamic adjustment can be achieved according to the complexity of a non-linear system, implementation is easy, and the non-linear characteristic and the memory effect of the power amplifier can be well compensated for.

By a simple computation, orthogonal errors from an orthogonal modulator and an orthogonal demodulator are separately corrected. Based on the amplitude of a demodulated signal, an orthogonal-error detection unit (320) detects orthogonal errors from an orthogonal modulation unit (140) and an orthogonal demodulation unit (230). Specifically, according to the distribution of transmission signal points on an I-Q plane, demultiplexers (321 and 322) in an orthogonal-error detection unit (320) separate a demodulated signal into a signal on the I-axis and a signal on the Q-axis. Zero-crossing detection units (325 and 326) detect the amplitudes of the separated signals at the intersection of the I- and Q-axes. The orthogonal-error detection unit (320) detects the orthogonal errors based on results from comparing the amplitudes at said intersection. A gain control unit (330) controls settings for a transmission orthogonal-error correction unit (120) and reception orthogonal-error correction unit (250) according to the detected orthogonal errors.

A negative feedback amplifier has input portions for receiving input signals, adder circuits, a quadrature modulator for performing a quadrature modulation on outputs of the adder circuits, a first signal level variable control circuit for adjusting a level of an output signal from the quadrature modulator, an amplifier circuit for amplifying an output of the first signal level variable control circuit, a feedback circuit for negative feedbacking an output of the negative feedback circuit to the adder circuit, and a second control circuit for controlling an adjusting amount in the first signal level variable control circuit based on the output signal levels of the adder circuits so that the output signal levels of the adder circuits becomes predetermined values. The feedback circuit includes a first control circuit for controlling a signal level of the feedback circuit so that the output signal level of the amplifier circuit becomes a predetermined value.

Provided is a measuring apparatus which measures a quadrature modulator, including a supplying section supplying the quadrature modulator with a reference I signal having a predetermined frequency and a reference Q signal whose phase is shifted by 90 degrees from the reference I signal, an extracting section extracting, from a modulation signal output from the quadrature modulator by applying quadrature modulation to the reference IQ signals, a main signal component as the reference IQ signals modulated, and an image signal component occurring at a position symmetric to the modulated reference IQ signals with respect to the carrier signal, and a measurement value calculating section calculating at least one of a carrier phase error and amplitude error which occur between I signal and Q signal sides of the quadrature modulator, and a skew between IQ signals of the quadrature modulator, based on the main signal component and image signal component.

A transmitting circuit apparatus has a first digital modulator and a second digital modulator for modulating an I signal and a Q signal which are multi-valued digital baseband modulation signals, into a digital I signal and a digital Q signal, respectively, having the number of bits smaller than that of the baseband modulation signals; and a quadrature modulator for outputting a signal synthesized from the signals generated by modulating (two) carrier waves each having a phase perpendicular to each other by using the modulated I and Q signals, respectively.