Abstract: Embodiments enable a multi-band transmitter with significantly reduced architecture area by allowing maximum reuse of transmitter stages across supported frequency bands and signal standards. Further, embodiments allow a monolithic transmitter implementation by providing an integration-friendly differential to single-ended conversion stage. According to embodiments, the differential to single-ended conversion stage is readily configurable according to the frequency band and signal standard of operation of the transmitter.

Abstract: The present invention is related to integrated multi-datastream transmission technology, more particularly, to integrated multi-datastream modulation technology. According to one aspect of the present invention, there is provided a modulation equipment (10), including: a symbol integration means (101), configured to combine a first bit stream with a second bit stream to form a symbol to be modulated; a symbol mapping means (102), configured to map the symbol to be modulated into a QAM modulation symbol according to a set of predetermined mapping rules; wherein, in the set of predetermined mapping rules, multiple constellations corresponding to any first bit stream are located in at least two quadrants in the constellation diagram, while multiple constellations corresponding to any second bit stream are located in at least two quadrants in the constellation diagram. The integrated transmission of a first service data and a second service data (e.g.

Abstract: A quadrature amplitude modulator is provided. An oscillator generates an in-phase carrier signal having a rectangular wave, a trapezoidal wave or a waveform similar to these, and a quadrature carrier signal, the phase of which is shifted by ¼ cycle relative to the in-phase carrier signal. A multi-level driver generates an in-phase modulated signal by amplitude modulating the in-phase carrier signal with an analog in-phase baseband signal having a discrete voltage level or current level in accordance with the in-phase baseband data. Likewise, the multi-level driver generates a quadrature modulated signal by amplitude modulating the quadrature carrier signal with an analog quadrature baseband signal having a discrete voltage level or current level in accordance with the quadrature baseband data The multi-level driver generates a modulated signal, the amplitude of which takes a discrete level, by combining the modulated signals together.

Abstract: A quadrature modulator has first to fourth transistors, a first node, a second node, and a first output node. A non-inversion in-phase analog signal, an inversion in-phase analog signal, a non-inversion quadrature analog signal, and an inversion quadrature analog signal are supplied to input electrodes of the first to fourth transistors, respectively. Control electrodes of the first to fourth transistors respond to a non-inversion in-phase RF signal, an inversion in-phase RF signal, a non-inversion quadrature RF signal, and an inversion quadrature RF signal, respectively. Output electrodes of the first and second transistors are coupled to the first node, and output electrodes of the third and fourth transistors are coupled to the second node. A first high-pass filter is coupled between the first node and the first output node, and a second high-pass filter is coupled between the second node and the first output node.

Abstract: The invention achieves carrier and clock frequency synchronization in QAD packet communications systems. The invention involves using frequency-hopping radio systems that use pseudo-noise data sequences to mark the beginning of data transmissions and carrier frequency switches. The invention involves transmitting in each of the quadrature channels at an initial carrier frequency a first signal over consecutive time intervals and after transmitting the first signal, transmitting in each of the quadrature channels at a second carrier frequency a second signal over consecutive time intervals.

Abstract: A test apparatus includes digital modulators provided in increments of multiple channels. A baseband signal generator performs retiming of data input as a modulation signal for the in-phase (quadrature) component, using a timing signal the timing of which can be adjusted, thereby generating a baseband signal. A driver generates a multi-value digital signal having a level that corresponds to the baseband signal output from the baseband signal generator. A multiplier amplitude-modulates a carrier signal with the multi-value digital signal. An adder sums the output signals of the multipliers.

Abstract: Communication systems are described that use geometrically shaped constellations that have increased capacity compared to conventional constellations operating within a similar SNR band. In several embodiments, the geometrically shaped is optimized based upon a capacity measure such as parallel decoding capacity or joint capacity. In many embodiments, a capacity optimized geometrically shaped constellation can be used to replace a conventional constellation as part of a firmware upgrade to transmitters and receivers within a communication system. In a number of embodiments, the geometrically shaped constellation is optimized for an Additive White Gaussian Noise channel or a fading channel.

Abstract: The present disclosure provides Radio Frequency (RF) drive level control systems and methods for an Electro-Optic (EO) M-ary Phase-Shift Keying (M-PSK) phase modulator. Specifically, an M-PSK drive waveform is tightly controlled for maximum symmetry in the associated constellation. In an exemplary embodiment, the present disclosure includes an M-PSK transmitter, an M-PSK electro-optic phase modulator, and phase modulation method that each control RF drive level based upon a carrier suppression ratio defined as a measure of ratio of a modulated time-averaged E-field to the magnitude of the E-field. In an exemplary embodiment, the carrier suppression ratio is measured based on a modulation depth measurement.

Abstract: Enhanced polar modulator for transmitter. Within a phase locked loop (PLL), two point modulation topology is employed in which phase information passes through a limiter (e.g., a ±90° or ±?/2), the phase information dynamic range is divided by a factor (e.g., by 2), and a maximum frequency deviation is also divided by a factor (e.g., by 2). Then, a double balanced up-converter mixer/modulator performs gain adjustment (e.g., magnitude and/or amplitude adjustment) and phase changes of 0° and +180° or 0 and +? (e.g., negative gains values may be employed). Phase adjustment in such an architecture is split and provided to both the PLL and to the mixer/modulator of such a polar modulator within a transmitter module such as may be implemented within a communication device (e.g., which may be a wireless communication device). This architecture that includes a PLL with a double balanced up-converter mixer/modulator suppresses even harmonics.

Abstract: A beamforming RF vector modulator is provided. The beamforming RF vector modulator includes a first amplification part for amplifying an input single RF signal and outputting differential RF signals of different phases; an RF signal converter for receiving the differential RF signals and outputting four signals I+, I?, Q+, and Q? of different phases, the RF signal converter comprising a polyphase filter which is virtually opened by resonance of an output terminal comprising a transmission line load; a Variable Gain Amplifier (VGA) part comprising a I VGA which varies an amplitude and a polarity of the signals I+ and I?, and a Q VGA which varies the amplitude and the polarity of the signals Q+ and Q?according to a control signal; and an RF signal synthesizer for synthesizing an output current of the I VGA and an output current of the Q VGA.

Abstract: The present application relates to a digital modulator comprising an output stage comprising a number of unit cell arrays, and a sampling stage. The present application relates also to a communication device comprising said digital modulator, a method for digitally modulating and a computer program product. More particularly, the digital modulator comprises an output stage comprising a number of unit cell arrays, wherein the output stage comprises at least one carrier frequency signal input terminal configured to receive a carrier frequency signal. The digital modulator comprises a sampling stage connectable to the output stage, wherein the sampling stage is configured to oversample at least one data input signal. The digital modulator comprises at least one sampling clock generating device configured to generate at least one sampling clock signal depending on the number of arranged unit cell arrays and the carrier frequency signal.

Abstract: Apparatus and methods for improving the spectral performance of a polar modulator are described. A composite FM signal component of a composite polar transmit signal may be processed by monitoring the FM signal to detect a transient burst component, and, responsive to detection of a transient burst, generating a spectrally friendly replacement signal component that may be combined with the FM signal to improve spectral performance of the composite signal. In addition, an associated AM component of the composite transmit signal may be filtered to further improve spectral performance.

Abstract: A distributed weighting network that employs a summing line including distributed summing blocks disposed thereon. Each summing block includes a plurality of resistors that define a resistor divider network. Each summing block includes at least three ports having an input port, an output port and at least one signal port. A signal applied to each signal port of the summing blocks is modified in amplitude by the resistor divider network and summed with the signal propagating along the summing line being input to the input port and output from the output port of each summing block to provide a combined signal. The distributed weighting network can be part of a digital-to-analog converter or a QAM modulator.

Abstract: Provided is a transmission circuit that operates highly efficiently by avoiding deterioration of the linearity of an output signal and suppressing occurrence of distortion of the output signal, when using the envelope tracking method. In this transmission circuit, offset control section (160) sets voltage that makes the corrected envelope signal level equal to or higher than the delayed envelope signal level, as offset voltage. By this means, the corrected envelope signal level becomes equal to or higher than the delayed envelope signal level, so that it is possible to prevent the power supply voltage from being lower than the optimal power supply voltage, making it possible to prevent the linearity of an output signal from deteriorating in power amplifier (130).

Abstract: The present invention relates to a polar modulation apparatus and method, in which a polar-modulated signal is generated based on separately processed phase modulation (PM) and amplitude modulation (AM) components of an input signal. An amplified polar modulated output signal is generated in accordance with the phase modulation and amplitude modulation components by using a differential power amplifier circuitry(30) and supplying an amplified phase modulation component to a differential input of the differential power amplifier circuitry(30). A bias input of the differential power amplifier circuitry(30) is controlled based on the amplitude modulation component, so as to modulate a common-mode current of the differential power amplifier circuitry(30). Thereby, a new concept of a polar modulator with static DC-DC converter and power and/or efficiency and/or linearity controlled output power amplifier can be achieved.

Abstract: A quadrature demodulation circuit includes: first to fourth mixers to receive a modulation signal; a phase shifter to supply to the first and third mixers a first local frequency signal, to supply to the second mixer a second local frequency signal having a designated phase difference relative to the first local frequency signal, and to supply to the fourth mixer a third local frequency signal that is an inverse in phase to the second local frequency signal; a first adder to add a signal output from the first mixer and a signal output from the second mixer and to output a first demodulation signal; and a second adder to add a signal output from the third mixer and a signal output from the fourth mixer and to output a second demodulation signal.

Abstract: Various embodiments relate to a transmission circuit and related method of shaping the transmission spectrum of a carrier signal. The transmission circuit may comprise a plurality of switching amplifier stages that are controlled by a modulation sequence produced by a transmission (TX) modulator. The TX modulator may receive the transmission data as a sequence of bit groups and may produce a modulation sequence including a plurality of control bits that may drive each of the switching amplifier stages. In some embodiments, one or more pulse-shaping filters may modify in-phase (I) and quadrature (Q) phase components of the transmission data. The modified components may directly shape spectral content of the output signal produced by a transmission driving circuit. Higher quantities of amplifier stages included in the transmission driving circuit may add higher granularity to the shape of the spectrum of the output signal.

Abstract: A polar modulator of the present invention includes: a first function block which generates an amplitude signal and a phase signal; a second function block which adjusts the signal delay between the amplitude signal and the phase signal; a third function block which allows the low frequency component of the amplitude signal to pass therethrough; a fourth function block which modulates the phase of the phase signal; a fifth function block which outputs a modulation voltage, based on the amplitude signal; a sixth function block which modulates the amplitude of the phase signal, based on the modulation voltage; a seventh function block which measures the temperature of at least one function block; and an eighth function block which calculates a compensation amount for the signal delay, based on the measured temperature. The second function block adjusts the signal delay, based on the compensation amount.

Abstract: A multi-phase pulse-modulated polar transmitter and a method of generating a pulse-modulated envelope signal carrying modulated RF signal. Multi-phase pulse modulation technique or similar multi-phase pulse modulation techniques are employed in conjunction with a plurality of power amplifiers to enhance the bandwidth of the transmitter and to reduce out-of-band emissions and noises while easily synchronizing the phase and envelope of the input signal.

Abstract: Provided is a modulation apparatus that outputs an output signal having a designated amplitude and a designated phase, comprising a first variable delay section that outputs a first delayed signal obtained by delaying a periodic signal by a set delay time; a second variable delay section that outputs a second delayed signal obtained by delaying the periodic signal by a set delay time; an adding section that adds together the first delayed signal and the second delayed signal, and outputs the result as the output signal; and a setting section that sets the delay times for the first variable delay section and the second variable delay section according to the designated amplitude and the designated phase.

Abstract: A 4-phase filter includes four filter units including resistors and capacitors which inputs input signals, and provides the input signal via a switch buffer to a secondary capacitor provided in parallel to a primary capacitance of each filter unit, thus enabling a shift of an operational frequency band according to whether or not the switch buffer is in an output-high-impedance state.

Abstract: The present disclosure relates to using windowing to reduce the bandwidth of an amplitude modulation (AM) power supply input signal (PSIS), which is fed to an AM power supply to provide envelope power to an RF power amplifier stage via an AM power supply output signal. By reducing the bandwidth, noise levels from the AM power supply may be reduced. However, although the bandwidth of the AM PSIS is reduced, the AM power supply output signal may track the AM of the RF power amplifier stage closely enough to meet linearity requirements and to provide high efficiency. The windowing may be based on dividing a stream of AM input samples into a stream of input windows, from which a stream of output windows is created to provide a stream of windowed AM input samples that are used to provide a windowed AM PSIS to the AM power supply.

Abstract: The communications terminal and acquisition method is for use with Continuous Phase Modulation (CPM) and Phase Shift Keying (PSK) modulation-type signals, each modulation-type signal having a respective preamble phasing sequence. The communications terminal may include a wireless communications device to receive a modulated signal having one of the CPM and PSK modulation types, and having a symbol rate. A controller may be included to cooperate with the wireless communications device to perform a transform process, such as a Fourier Transform (FT) process, on the received modulated signal to detect the modulation type and the symbol rate of the received modulated signal based upon the preamble phasing sequence. Carrier phase and frequency of the received modulated signal may be estimated based upon bin amplitudes. Also, symbol timing may be estimated based upon a phase difference between tones associated with the preamble phasing sequence.

Abstract: Apparatus and methods for adjustment of spectral signal characteristics in polar modulators are described. A composite signal detection circuit is configured to detect when a signal trajectory of a composite signal provided to the polar modulator passes near the origin of a complex plane associated with the composite signal, and then adjusts the composite signal to pass through the origin. A spectral adjustment circuit is described to adjust AM and FM or PM components of the composite signal to reduce the deviation of an FM component of the composite signal.

Abstract: Briefly, in accordance with one or more embodiments, in a pulse position and pulse position modulation out-phasing transmitter, the range of the phase angle, theta, may be divided into more than one range to drive a first power amplifier with a first range of theta, and to drive a second power amplifier with a second range of theta. In one or more embodiments, a main power amplifier is driven with a first phase range having a higher probability density function, and an overload power amplifier is driven with a first phase range having a lower probability density function. In one or more embodiments, a full adder may be used to combine the two phases wherein the sum signal is used to drive the main power amplifier, and the carry signal is used to drive the overload power amplifier.

Abstract: Apparatus and methods for enhancement of performance in polar modulators are described. In one implementation, an FM signal component is divided into a coarse FM signal and a residue FM signal to be applied to a VCO for generation of a modulation signal. The coarse FM signal may be proportional to a threshold value when the FM signal exceeds the threshold, while the residue FM signal may be proportional to the difference between the FM signal and coarse FM signal.

Abstract: An apparatus, method and computer program, the apparatus including: a modulator including a first input for receiving a data signal and a second input for receiving an output signal from a phase locked loop wherein the modulator is for modulating the output signal from the phase locked loop using the data signal and providing the modulated signal to an output for connection to an amplifier; and a phase shifter configured to result in a predetermined phase shift to the modulated signal.

Abstract: A method for tuning a digital compensation filter within a transmitter includes: obtaining at least one loop gain calibration result by performing loop gain calibration based upon signals of at least a portion of the transmitter, and obtaining at least one resistance-capacitance (RC) detection result by performing RC detection on the portion of the transmitter without individually measuring resistance values of resistors therein and capacitance values of capacitors therein, wherein the RC detection result corresponds to a detected value representing a product of a resistance value and a capacitance value, and the digital compensation filter includes a gain compensation module and an RC compensation module; and tuning the digital compensation filter by respectively inputting the loop gain calibration result and the RC detection result into the gain compensation module and the RC compensation module. An associated digital compensation filter and an associated calibration circuit are also provided.

Abstract: A modulation apparatus comprising a first modulating section that outputs a first modulated signal having a fixed amplitude and a set phase; a second modulating section that outputs a second modulated signal having the fixed amplitude and a set phase; an adding section that outputs the output signal as the sum of the first and second modulated signals; a calculating section that calculates two phases to be set respectively in the first and second modulating sections, based on designated amplitude and phase; an allocating section that allocates, for the first and second modulated signals, the two phases calculated by the calculating section such that the first and second modulated signals are each connected more smoothly; and a setting section that sets the phase allocated for the first modulated signal in the first modulating section and sets the phase allocated for the second modulated signal in the second modulating section.

Abstract: A quadrature out-phasing system comprising: a first baseband signal modifier (6) arranged to receive a first baseband signal component (2) and output a first constant envelope RF carrier (12) and a second constant envelope RF carrier (14); and a second baseband signal modifier (8) arranged to receive a second baseband signal component (4) and output a third constant envelope RF carrier (16) and a fourth constant envelope RF carrier (18). The system may further comprise: a first signal combiner (500) arranged to combine the first constant envelope RF carrier (12) and the second constant envelope RF carrier (14), and arranged to output a first RF PWM signal (94); and a second signal combiner (502) arranged to combine the third constant envelope RF carrier (16) and the fourth constant envelope RF carrier (18), and arranged to output a second RF PWM signal (96).

Abstract: The method and system are disclosed for automatic feedback control of integrated optical quadrature modulator for generation of optical quaternary phase-shift-keyed signal in coherent optical communications. The method comprises the steps of detecting at least a part of an output optical signal from the QPSK modulator, extracting of a particular portion of the output signal in frequency domain, and processing the signal in frequency domain to optimize the transmission of an optical link. The system and method of optical communications in fiber or free space are disclosed that implement the quadrature data modulator with automatic feedback control.

Abstract: Various apparatuses and methods for offsetting the phase and/or frequency of a clock signal are disclosed herein. For example, some embodiments provide an apparatus for generating a clock signal, including a quadrature delay circuit connected to an input clock signal. The quadrature delay circuit outputs components of the input clock signal with different phase shifts. A first amplitude modulator is connected to the first output of the quadrature delay circuit, and a second amplitude modulator is connected to the second output of the quadrature delay circuit. A summer combines the output of the first and second amplitude modulators.

Abstract: An apparatus for phase modulation includes a delay locked loop configured to generate from a reference signal a plurality of phase shifted signals, each of the phase shifted signals being locked to the reference signal and having a different phase shift from the other phase shifted signals with respect to the reference signal, and a multiplexer configured to select one of the phase shifted signals.

Abstract: A circuit for providing AM/PM modulation is described. The circuit provides two drive signals which are later combined in a constructive/destructive fashion. The circuit provides AM modulation with a drive signal having a consistent power level modulated to have varying pulse widths in order to provide variable power within each cycle.

Abstract: A two-point phase modulator and a method of calibrating conversion gain of the same are provided. The two-point phase modulator locks an output frequency signal by charging and pumping charge in a phase-locked loop (PLL) circuit at the beginning of operation, opens a loop of the PLL circuit for a period of time, and applies a step signal, thus calibrating conversion gain of a modulation signal that controls the output frequency signal. Thus, the conversion gain may be accurately calibrated by the calibration operation at one time.

Abstract: A redundancy system for a co-channel telecommunication system and related methods. Implementations of the redundancy system may include at least a first modulator and a second modulator having a symbol mapper coupled to a parallel bit signal. The symbol mapper may be configured to route each of a plurality of parallel bits received through the parallel bit signal to a plurality of significant bit signals. In a first implementation, a plurality of significant bit signal multiplexers may be used to switch the plurality of parallel bit signals to allow the first and second modulators to operate in either a redundant or operating mode. In a second implementation, a premapped symbol (PMSI) encoder and a PMSI decoder may be used to transmit the plurality of significant bit signals across an interface bus as a real dual-data rate (DDR) signal and an imaginary DDR signal.

Abstract: Provided is a modulation device including a signal selection circuit selecting two carrier signals from a plurality of carrier signals having the same frequency and the same phase difference according to a defined control signal and outputting the selected carrier signals, and a phase interpolator adjusting the phase in smaller units than the phase difference between the plurality of carrier signals according to the control signal and modulating the frequency or the phase of the carrier signal into a baseband signal based on the carrier signals selected by the signal selection circuit to generate a carrier wave signal.

Abstract: Provided is a digital modulator, including a carrier wave output section that outputs a carrier wave, a variable delay section that delays the carrier wave, and a delay amount setting section that sets a delay amount by which the variable delay section delays the carrier wave based on transmission data being transmitted by the carrier wave. The variable delay section may include a multi-stage delay buffer circuit in which delay buffers that delay an input signal by a unit shift amount are connected in a cascade connection, the multi-stage delay buffer circuit may receive the carrier wave at a first-stage delay buffer as input, and the delay amount setting section may include a multiplexer that selects either an output from the carrier wave output section or an output from each stage of the multi-stage delay buffer circuit.

Abstract: A multi-phase ultra-wideband signal generator uses differential pulse oscillators. The multi-phase ultra-wideband signal generator using differential pulse oscillators includes N pulse oscillators for generating pulse signals based on a supply of power, and further comprises N inverting amplification units for outputting inverted amplified signals of output signals of the N pulse oscillators when a number of pulse oscillators is at least two, wherein, when the number of pulse oscillators is an even or odd number, the pulse oscillators are arrayed such that they have a connection form in which output terminals OUT(+) and OUT(?) of a relevant pulse oscillator are connected to output terminals OUT(+) and OUT(?) of a next pulse oscillator through a relevant inverting amplification unit, and the connection form is consecutively applied to the pulse oscillators.

Abstract: The present disclosure relates to I/Q modulation circuits, devices, and methods.

Abstract: In one embodiment, a switch provides output to a digital radio frequency (RF) modulator having a filtered input stage. The switch is configured to selectively provide a zero power data signal to the RF modulator based on a transient event control signal received at the switch.

Abstract: A circuit includes a phase shifter configured to selectively shift a phase of a baseband phase signal in accordance with a zero crossing signal to output a selectively phase-shifted signal, a phase modulator configured to provide a phase modulated carrier signal in accordance with the selectively phase-shifted signal, and an inverter configured to selectively invert the phase modulated carrier signal in accordance with the zero crossing signal.

Abstract: A bi-phase modulator including a driver and a mixer. The driver includes a prescaler having an input for receiving a signal and an output for outputting a baseband signal. The mixer includes a mixer having an input coupled to the output of the prescaler for receiving the baseband signal output by the prescaler. The baseband signal output by the prescaler drives the mixer so as to output a modulated waveform from an output of the mixer.

Abstract: A distortion compensating circuit is provided in which, in the polar modulation system, while suppressing increase of compensation data and increase of the circuit scale, a modulated signal can be correctly expressed, or low-distortion characteristics of a power amplifier can be realized. Based on a steady characteristic compensating circuit 11 which stores an output signal amplitude and output phase characteristics with respect to a control voltage in a steady state, amplitude adjustment is executed on amplitude information r11(t) on which amplitude correction is performed, by a first amplitude information adjusting portion 13, whereby the output-response characteristics of an output signal amplitude of an amplifier with respect to a change of the control voltage can be improved.

Abstract: A differential positive coefficient weighted quadrature modulator is actuated responsive to quadrature clock signals and positive digital modulation signals input to the modulator. The modulator includes an I-channel positive coefficient weighted modulator (PCWM) and a Q-channel PCWM. The I-channel PCWM has differential output nodes configured to output a differential I-channel signal responsive to the state of first and second positive digital modulation signals and first and second complimentary quadrature clock signals input to the I-channel PCWM. The Q-channel PCWM has differential output nodes configured to output a differential Q-channel signal responsive to the state of third and fourth positive digital modulation signals and third and fourth complimentary quadrature clock signals input to the Q-channel PCWM.

Abstract: There is provided a modulation circuit including a sampling unit that over-samples an input digital signal based on a multiplying clock signal, and outputs a first over-sampling signal, a first frequency conversion unit that outputs a first high-frequency signal based on the first over-sampling signal and a reference signal, a first filter unit that outputs a second high-frequency signal based on a second over-sampling signal obtained by delaying the first over-sampling signal by one clock and the reference signal, a second filter unit that outputs a third high-frequency signal based on a third over-sampling signal obtained by delaying the second over-sampling signal by one clock and the reference signal, and an adder unit that adds the first high-frequency signal, the second high-frequency signal, and the third high-frequency signal, and outputs an output signal.

Abstract: The present invention relates in general to transferring the envelope information of a polar modulated signal to a varying pulsewidth signal, while the phase modulation is direct transferred to the phase modulation of this PWM signal. Accordingly, the resultant signal is a PWM-PPM-signal. Such a signal can efficiently amplified by use of switching amplifying stages. By the present invention four pre-distorted baseband signals are applied basically to 4 linear RF mixers and a two adders, which are, the only needed external RF building blocks to build the modulator according to the invention. That is, the basic idea of the invention resides in the way of modulation of the four baseband signals and the way of combining of the RF modulated signals.

Abstract: A quadrature modulator and a method of calibrating same by applying a first test tone signal to an in-phase modulation branch input of the modulator and a ninety degree phase-shifted version of the first test tone signal to a quadrature modulation branch input of the modulator. The carrier leakage level in an output signal of the modulator is measured and in response base band dc offset voltages are adjusted to minimize the carrier leakage. A second test tone signal is applied to the in-phase modulation branch input and a ninety degree phase-shifted version of the second test tone signal to the quadrature modulation branch input. The level of an undesired upper sideband frequency component in the output signal is measured and in response base band gains the in-phase and quadrature modulation branches and a local oscillator phase error are adjusted to minimize the undesired side band.

Abstract: A DC offset cancellation circuit used for compensating a carrier leak at an output signal of a modulator has a sign extraction unit for extracting sign of an information signal which is applied to the modulator, an envelope detecting unit for performing envelope detection on the output signal of the modulator to output the resulting envelope, a slope detecting unit for performing polarity detection on the slope of the envelope; and a signal processing unit for generating a DC offset cancellation signal for compensating the carrier leak based on the result of the sign extraction and the result of the polarity detection. The signal processing unit preferably calculates the DC offset cancellation signal by multiplying the sign of the information signal by the polarity of the slope of the envelope and accumulating the result of multiplication.

Abstract: A quadrature modulator (QM) may be calibrated by determining total equivalent offsets in the I- and Q-channels, a total equivalent gain imbalance between the I- and Q-channels, and a total equivalent phase skew between the I- and Q-channels. These values may be obtained by taking various scalar measurements of the image to signal ratio (ISR) and carrier to signal ratio (CSR) of the QM, while alternatively altering the system gain imbalance, system phase skew, I-channel offset and Q-channel offset using a respective gain parameter, phase parameter, I-channel offset parameter, and Q-channel parameter. The gain and phase parameters may be defined in terms of the ISR, and the channel offset parameters may be defined in terms of the CSR. The system gain imbalance, system phase skew, and total offset in the channels may then be calculated based on the various ISR and CSR measurements.