Abstract: Provided are an image signal rejection method capable of avoiding demodulation of an image signal along with a real signal in a radio frequency (RF) signal and a low IF receiver of rejecting an image signal by using the method. The low IF receiver of rejecting an image signal includes a low noise amplifier, a quadrature I/Q mixer, a signal complex filter, and a phase and gain control block. The low noise amplifier amplifies a radio frequency (RF) signal. The quadrature I/Q mixer generates an I signal and a Q signal by down-converting the amplified RF signal into an IF signal. The phase and gain control block generates an I? signal and a Q? signal which are obtained by changing phases and amplitudes of the I signal and the Q signal by using a real signal. The signal complex filter minimizing the image signal in the IF signal and passing the real signal by performing filtering on the I? signal and the Q? signal.

Abstract: Certain aspects of a method and system for mitigating effects of pulling in multiple phase locked loops in multi-standard systems may include selecting an input frequency range of operation at a voltage controlled oscillator based on a particular wireless band of operation in a system that handles a first wireless communication protocol and a second wireless communication protocol. An image rejection mixer may be enabled to generate an output signal for the particular wireless band of operation based on mixing a plurality of received signals within a selected frequency range. An in-phase (I) component and a quadrature (Q) component of the generated output signal may be generated by utilizing a RC-CR quadrature network.

Abstract: Provided is a poly-phase filter capable of removing an image frequency of a terrestrial digital multimedia broadcasting (T-DMB) receiver in a low intermediate frequency (IF) structure applied to a mobile communication terminal and a receiver having the poly-phase filter. The poly-phase filter includes: a calibration control block for generating first and second filter characteristic control signals which determine electrical characteristics of the filter in response to a control signal including instructions for changing the characteristics of the poly-phase filter and holding the changed values; and a poly-phase filter block for performing filtering on a plurality of input signals having different phases from each other in response to the first and second filter characteristic control signals. Accordingly, the poly-phase filter has advantages of having constant electrical characteristics regardless of changes in a manufacturing process and temperature and a high-performance image rejection function.

Abstract: Provided is an orthogonality compensating device that compensates for orthogonality between a real signal and an imaginary signal of complex digital intermediate frequency signals, the orthogonality compensating device including: a first processing unit that outputs a first signal obtained by calculating one of the real signal and the imaginary signal by using a first coefficient and a second coefficient; and a coefficient specifying unit that specifies the first coefficient such that the first signal has the same amplitude as the other of the real signal and the imaginary signal, and specifies the second coefficient such that the first signal is orthogonal to the other of the real signal and the imaginary signal, by using the first signal and the other of the real signal and the imaginary signal.

Abstract: Provided is an orthogonality compensating device that compensates for orthogonality between a real signal and an imaginary signal of complex digital intermediate frequency signals, the orthogonality compensating device including: a detector that outputs a detection result indicating whether the complex digital intermediate frequency signals include an image frequency signal; a first processing unit that outputs a first signal obtained by adding a first scalar signal obtained by multiplying the imaginary signal by h1 and a second scalar signal obtained by multiplying the real signal by h2; a second processing unit that outputs a second signal obtained by multiplying the imaginary signal by h3; and a coefficient specifying unit that specifies h1 and h3 such that the first signal has the same amplitude as the second signal, specifies h2 such that the first signal is orthogonal to the second signal, and selects a sign of h2 depending on the detection result.

Abstract: A receiver (20) for use in wireless communications with plural transmitters (22) comprises transmitter selection logic (34); a signal estimator (36); and an image estimator (38). The image estimator (38) is configured to form an estimate of an image signal occurring on the second sub-carrier and attributable to a transmission of the first transmitter. The signal estimator (36) is configured, e.g., to use the estimate of the image signal and a signal received on the second sub-carrier to obtain an estimate of a portion of the signal received on the second sub-carrier which is attributable to the second transmitter. Thus, the receiver (20) is able to determine the portion of the signal received on the second sub-carrier which is attributable to the second transmitter in a way that compensates for the image signal occurring at the second sub-carrier.

Abstract: The receiver, which enables rejection of image signals with higher accuracy over wider frequency band, can be provided as a low IF receiver by inputting a calibration signal of frequency fi (1?i?N) before reception of signals and determining the frequency response fa(z) to fd(z) of a calibrating filter in a filter mismatch calibrating circuit (FIL_CAL) 195 to make zero amplitude and phase mismatches between the I component and Q component of the quadrature demodulation signal at the frequency fIFi.

Abstract: The present invention is a quadrature VLIF receiver, including calibration circuitry, and methods to closely match signal processing of an in-phase signal path and a quadrature-phase signal path to optimize VLIF image rejection. The calibration circuitry includes a variable gain variable-phase calibration signal generator, a variable gain amplifier for each signal path, phase adjustment circuitry for each signal path, and switching circuitry to support calibration steps. The calibration signal generator supplies a calibration signal at the same frequency as mixer local oscillator signals; therefore, during calibration, all signals downstream of the VLIF mixer are at DC, which simplifies calibration measurements, thereby minimizing calibration times.

Abstract: Methods and systems for a transmitter LOFT cancellation scheme that maintains IQ balance are disclosed. Aspects of one method may include providing current compensation to both differential inputs of a mixer for each of I and Q channels. An initial current compensation of X units may be provided, followed by subsequent compensation as needed. The initial compensation may be provided to each differential input of the mixers used for I and Q channels. The subsequent current compensation for the I channel may be independent of the subsequent current compensation for the Q channel. Subsequent current compensation to a first differential input for a mixer may be increased by Y units while decreasing current compensation to the second differential input of the mixer by Y units. In this manner, the DC common mode level for the mixer may remain the same at the initial DC compensation current of X units for both mixers.

Abstract: A radio frequency (RF) receiver and receiving method are provided which can remove a leakage component from a received signal by using a local signal. In the RF receiver, a noise removing unit controls a gain and a phase of a local signal LOI according to a phase THETA and a gain AMPTD detected in a MODEM, estimates a signal Vcal corresponding to a noise component introduced into a received RF signal RXIN, and removes the estimated signal Vcal from the received RF signal RXIN. In this manner, a clean RF signal RXO, which does not include a noise component, is frequency-down converted in a receiving unit.

Abstract: Systems and techniques relating to image cancellation in received communications signals are described. In one aspect, a received communications signal can include a desired signal and an image signal. A leakage tracing signal can be generated, and the image signal can be removed from the communications signal using the leakage tracing signal mixed with the communications signal. Implementations can include generating a first channel signal and a second channel signal, generating a first filter using the first channel signal and the leakage tracing signal, and generating a second filter using the second channel signal and the leakage tracing signal. Removing the image signal from the communications signal can include filtering the first channel signal using the second filter to obtain a first filtered signal, filtering the second channel signal using the first filter to obtain a second filtered signal, and subtracting the second filtered signal from the first filtered signal.

Abstract: A phase mismatch compensation system includes a first summer that has a first input that communicates with a first phase of a received signal and an output. A second summer has a first input that communicates with a second phase of the received signal and an output, wherein the second phase is offset from the first phase. A first filter selectively filters the output of the first summer. An adaptive control module determines a predicted shift between the first and second phases of the received signal based on an output of the first filter and an actual shift between the first and second phases of the received signal. A correction module communicates with an output of the adaptive control module and the first phase and second phase of the received signal. The correction module outputs a mismatch correction to second inputs of the first and second summers respectively.

Abstract: A mobile wireless communications device, system and associated method includes a housing and circuit board that includes radio frequency (RF) circuitry and processor operative with each other. The RF circuitry includes a low-IF receiver circuit that is operative for maintaining an interferer signal at a same frequency side as a wanted signal relative to a local oscillator frequency setting, creating an interferer image signal, and filtering the image signal as substantially baseband frequency.

Abstract: A system and method are provided for compensating for an I/Q mismatch of either a direct conversion transmitter or a direct conversion receiver based on known short training symbols of a Short Training Sequence (STS) of packets transmitted according to the IEEE 802.11a or 802.11g standard. To compensate for an I/Q mismatch of a direct conversion transmitter, a packet including the STS is transmitted. Due to the I/Q mismatch of the direct conversion transmitter, the transmitter distorts the packet to provide a distorted packet including a distorted STS. Based on one or more short training symbols of the distorted STS and a known ideal short training symbol, a distortion matrix is determined. Subsequent packets transmitted by the direct conversion transmitter are pre-distorted based on the distortion matrix. Compensation of the I/Q mismatch of a direct conversion receiver may be performed in a similar fashion.

Abstract: A level comparator supplied with oscillation signal of local oscillator for comparing the signal level of oscillation signal with a certain predetermined threshold value, and a driving section interposed between the output of level comparator and a control section are provided. When the level comparator recognized that the signal level exceeded the threshold value, it puts the driving section into operation for bringing the control section into action.

Abstract: An apparatus for frequency direct conversion reception in a mobile communication terminal and method thereof are disclosed, by which a DC offset can be removed.

Abstract: The employment of cascoding in connection with improving mixer isolation in a Gilbert mixer circuit is provided. In this vein, there is broadly contemplated herein, inter alia, the provision of a mixer suitable for use in a direct-conversion radio receiver operating in the 57-64 GHz industrial, scientific, and medical (ISM) band. Such a receiver may be integrated along with a transmitter entirely on a silicon integrated circuit and can be used to receive and transmit data signals in such applications as wireless personal-area networks (WPANs). Numerous other applications, of course, are available for a mixer with improved LO-to-RF isolation, particularly at millimeter-wave frequencies where high LO-to-RF isolation is difficult to achieve.

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: A digital communication circuit can be implemented can be implemented in a CMOS, or other IC structure. The digital circuit can utilize negative frequency removers or image frequency removers in the digital domain. The circuit can include mixers, switches, a complex filter, a low noise amplifier and summers. The image frequency can be removed digitally.

Abstract: A test signal generation circuit includes a tuning circuit, a local oscillation circuit for forming orthogonal local oscillation signals, first mixer circuits for frequency-converting the reception signal into IF signals by the local oscillation signals, IF-filters for extracting the IF signals from outputs of the first mixer circuits, phase shift circuits for shifting phases of the IF signals extracted by the IF-filters, a first calculation circuit for outputting an IF signal through addition/subtraction of outputs of the phase shift circuits, a forming circuit for forming orthogonal alternate current signals having a frequency equal to a frequency of the IF signals, second mixer circuits for receiving the orthogonal alternate current signals and the local oscillation signals, and a second calculation circuit for outputting a signal through addition/subtraction of outputs of the second mixer circuits, wherein an output of the second calculation circuit is supplied to the tuning circuit as a test signal.

Abstract: A multi-mode, multi-band mobile station for use in wireless networks operating under different air interface standards. The present invention, the mobile station comprises a plurality of low-noise amplifiers. Each of the plurality of low-noise amplifiers is optimized for use in a selected frequency band. The mobile station also comprises a near-zero intermediate frequency (NZIF) broadband image rejection mixer for receiving an amplified RF signal from a selected one of the plurality of low-noise amplifiers and down-converting the amplified RF signal to produce a first analog intermediate frequency (IF) signal.

Abstract: A mixer is disclosed having an output stage with an amplifier or gain device configured in a feedback loop to maintain a virtual ground at the input to the gain device. The gain device provides significant dynamic range, gain, and the appropriate impedance matching to insure a low noise output signal of a desired magnitude. Use of an amplifying output stage removes the dependence between mixer gain and mixer configuration, such as mixer bias resistor value, while concurrently overcome undesirable flicker noise that results from use of active devices in the mixer bias structure. A stable virtual ground at the mixer output and gain device input provides linearity over frequency. The gain device may comprises an operational amplifier or trans-resistance/trans-conductance device.

Abstract: A high-frequency receiver and a portable device using the same receiver are proposed for reducing power consumption. Image interference determiner (44) determines whether or not image interference exists at the present position in a desirable channel to be received, which channel is obtained by a receiving section (39) or a GPS receiver (43). Power supply control circuit (47) switches mixer (49) from an image rejection mixer to a double balance mixer when determiner (44) determines no image interference involves. This mechanism allows mixer (49) to work as the double balance mixer circuit during the reception of channels free from image interference, so that a mixer consuming less power is achievable. When mixer (49) works as the image rejection mixer circuit, image interference can be reduced.

Abstract: A fully-integrated tuner for performing signal channel selection and image rejection in an analog cable television system is provided. Various embodiments disclose a tuner including an analog RF section to process an analog RF input signal and generate complex low intermediate frequency digital signals, and a signal processing section configured to reduce image and signal leakage in the complex low intermediate frequency signals. The signal processing section selects a signal channel of the complex low intermediate frequency signals and suppresses channel components adjacent to the signal channel. In one embodiment, the signal processing section includes a complex digital signal channel select filter to select the signal channel and suppress the adjacent channel components. In other embodiments, the complex digital signal channel select filter selects the signal channel, shapes the selected signal channel to generate a shaped signal channel, and equalizes a group delay of the shaped signal channel.

Abstract: Methods and apparatus to integrate image rejection into quadrature mixers are disclosed. A disclosed image-rejection quadrature mixer comprises a quadrature mixer, and a cross-coupled differential pair of transistors to provide a complex filter response, wherein the mixer and the transistors are integrated on a common silicon substrate.

Abstract: A multi-band receiver for use with satellite ranging systems is provided. The receiver has a simplified architecture in which input signals of various frequencies are multiplexed together to form a single composite analog signal. In accordance with one embodiment of the invention, this composite signal only requires a single RF circuit for down conversion to an intermediate frequency. The composite, downconverted signal is sampled, and the digitized samples are demultiplexed to form digital counterparts of the original signals from each frequency band. An embodiment for use with elements of a phased array antenna is also provided.

Abstract: A receiver (200) includes a transconductance mixer (310), a polyphase filter (320), and a transimpedance amplifier (330). The transconductance mixer (310) mixes a radio frequency (RF) voltage signal into a current signal having a plurality of phases using a local oscillator signal. The polyphase filter (320) filters the current signal to provide a filtered current signal. The transimpedance amplifier (330) converts the filtered current signal into an output voltage signal.

Abstract: Disclosed is a heterodyne receiver for low noise and image frequency repression, comprising: a low noise amplifier for receiving an input signal from an antenna and amplifying the signal while reducing a noise figure of the input signal; and a frequency converter for receiving both the input signal outputted from the low noise amplifier and a local oscillation signal, filtering the signals to repress gain of the input signal at an image frequency band and increase gain of the input signal at a signal frequency band, and converting the frequency of the signals to the intermediate frequency band.

Abstract: Analog-valued floating-gate transistors are used as trimmable circuit components for modifying and/or controlling the gain, phase, offset, frequency response, current consumption, and/or transfer function of signal pathways in parallel and/or serial processing circuits in radio frequency, analog, or mixed-signal integrated circuits.

Abstract: A signal input into an input terminal 1 is input into mixers 2, 4, and down-converted with local signals having a phase difference of 90 degrees, respectively, whereby an I-signal and a Q-signal are obtained. An output signal from the mixer 4 is delayed 90 degrees in phase by a phase shifter 6. An adder 7 outputs a sum signal of the I-signal and the Q-signal, and a subtracter 8 outputs a subtracted signal between the I-signal and the Q-signal. The sum signal and the subtracted signal are input into band pass filters 9, 10, in which signals in undesired frequency band are cut, then converted into digital signals by AD converters 11, 12 and input into a signal processor 13. In the signal processor 13, a correlation signal of the sum signal and the subtracted signal is formed, and an image signal included in the sum signal is removed using the correlation signal and the subtracted signal.

Abstract: An image rejection mixer includes a first mixer, a second mixer, a first output adjust circuit, and a second output adjust circuit. The first mixer is coupled to receive an input RF signal and a local oscillator signal and includes a first mixer stage and a first output load stage. The second mixer is coupled to receive the input RF signal and a phase-converted local oscillator signal and includes a second mixer stage and a second output load stage. The first output adjust circuit is coupled to the first output load stage for modifying the signal waveform of a first output signal of the first mixer. The second output adjust circuit is coupled to the second output load stage for modifying the signal waveform of a second output signal of the second mixer. In this manner, the near-perfect image rejection result in the final IF signal can be obtained.

Abstract: A receiver portion includes a bandpass filter (e.g. SAW filter) that performs channel selection from an input signal having a plurality of channels, and an image cancellation circuit that is in parallel with the bandpass filter. The bandpass filter performs channel selection to select a desired channel that falls in a passband of the bandpass filter. Since the passband is typically a few channels wide, the image channel falls outside the passband and is attenuated by the stopband attenuation of the bandpass filter. The image cancellation circuit includes an attenuator and a phase shifter. The attenuator is configured to have the same attenuation as the stopband attenuation of the bandpass filter at the image channel frequency, and phase shifter is configured to provide a phase shift of approximately 180 degrees. Therefore, the image cancellation circuit has an output that is equal in amplitude, but opposite in phase, to that of the bandpass filter at the image channel frequency.

Abstract: A grounded-emitter circuit is composed of a transistor, a first impedance circuit, and a second impedance circuit. The transistor is an NPN transistor, and the base of the transistor is an input terminal of the grounded-emitter circuit. The emitter of the transistor is grounded to GND via the second impedance circuit. The collector of the transistor is connected to a reference voltage source via the first impedance circuit, and is an output terminal of the grounded-emitter circuit. Further, the second impedance circuit is composed of a parallel resonance circuit consisting of an inductor and a capacitor. With this, it is possible to provide a grounded-emitter circuit capable of being built in an IC, and capable of removing an image frequency signal in a simple circuit configuration.

Abstract: In one aspect this invention provides a radio frequency receiver for coupling to an antenna. The receiver includes a downconversion mixer, an amplifier having an input coupled to the antenna and an output coupled to a first input of the mixer for providing a received frequency signal to the mixer and a voltage controlled oscillator having an output coupled to a second input of the mixer for providing a mixing frequency signal to the mixer. In the preferred embodiments the components of the amplifier and the voltage controlled oscillator are arranged to exhibit a substantially identical resonant circuit topology and are implemented in the same integrated circuit. In the preferred embodiments the amplifier and the voltage controlled oscillator each include calibration circuitry coupled to a calibration signal for compensating for integrated circuit component value variations, and where a calibration signal used for the voltage controlled oscillator is used as well for the amplifier.

Abstract: Disclosed are systems and methods which utilize an image reject mixer in an out-of-band mixer application such as in a forward data channel frequency converter. For example, according to a preferred embodiment, an image reject mixer is utilized to provide a relatively high degree of image rejection with respect to an out-of-band signal, thereby relaxing the requirement for filtering in the signal path leading to the mixer circuitry. Preferred embodiments of the invention are substantially or fully implemented utilizing integrated circuit technology.

Abstract: An RF communications circuit having a reduced LO feed through image reject mixer is disclosed. The image reject mixer includes a quadrature phase transconductance stage coupled to a quadrature phase mixer of a quadrature phase mixer module and an in-phase mixer of an in-phase mixer module. The image reject mixer further includes an in-phase transconductance stage coupled to an in-phase mixer of the quadrature phase mixer module and a quadrature phase mixer of the in-phase mixer module. The output of the quadrature phase mixer and in-phase mixer of the quadrature phase mixer module are cross-coupled to form a quadrature phase local oscillator (LO) output and wherein the output of the quadrature phase mixer and in-phase mixer of the in-phase mixer module are cross-coupled to form an in-phase local oscillator (LO) output.

Abstract: A tuner circuit includes a band selection filter coupled to receive an input RF signal and provide a band selected output signal where the band selection filter includes a bank of band pass filters. Each band pass filter includes an inductor and a variable capacitor forming an LC resonator where the inductor is an integrated planar spiral inductor. The tuner circuit further includes a frequency conversion circuit coupled to receive an input signal corresponding to the band selected output signal and provide a frequency converted output signal having a predetermined frequency. The integrated planar spiral inductor can be formed using a single metal spiral or multiple metal spirals. In a multi-spiral structure, a first metal spiral having an inward spiral pattern and a second metal spiral having an outward spiral pattern to form an inductor with large inductance, low series resistance and high Q values, even at low frequency.

Abstract: An algorithm for correcting the output of an analog I/Q demodulator without the need for calibration or storing state information. The output of the analog I/Q demodulator is digitized, and the discrete-time samples are divided into segments. A digital frequency transform (e.g., a Discrete Fourier Transform) is computed for each segment. The effects of the non-ideal I/Q demodulator are removed by identifying a set of image frequency candidates for each digital frequency transform, and for each image frequency candidate, estimating a set of demodulator imbalance parameters to characterize the demodulator imbalance at that frequency and correcting the digital frequency transform at the image frequency candidate using the imbalance parameters in order to minimize the effects of the imbalance. Each digital frequency transform is corrected independently and consequently no persistent state information needs to be saved between transforms.

Abstract: A matching unit includes a switching means for switching an inductance of a first inductor. This switching means sets an inductance such that a first inductor shows an inductance property to both of the VHF low-band and high-band, and shows a capacitance property to the UHF band. This structure allows the matching unit to achieve the matching for both the VHF low-band and high-band by just switching the two circuits of the VHF low-band and high-band, also allows the matching unit to show a capacitance property to the UHF band. Thus the loss produced in transmitting signals can be reduced, and the circuit can be simplified. As a result, the matching unit can be downsized, and the cost can be reduced.

Abstract: An image-rejecting antenna apparatus includes an antenna unit for receiving or transmitting a wireless signal and an image-reject unit for removing an image component signal having a predetermined frequency from among signals received from the antenna unit. In an image-rejecting antenna apparatus that receives a predetermined signal and provides a processed signal to a RF circuit unit for performing a predetermined function may also include an impedance matching unit for matching an impedance of the antenna unit with an impedance of the RF circuit unit and for providing the signal from which the image component signal has been removed to the RF circuit unit. A noise component of an image frequency that is transmitted to a subsequent circuit can be minimized or removed by including an image-reject unit when designing an antenna and a matching circuit, thereby improving the image-rejecting capabilities of an entire receiver.

Abstract: An image rejection quadratic filter is tunable to filter image frequencies over a wide band. In one embodiment, the image rejection filter includes in-phase and quadrature phase mixers. The image rejection has a fractional transfer function. The image rejection filter has two sub-circuits, wherein the first sub-circuit produces the imaginary component of the transfer function, and the second sub-circuit produces the real component of the transfer function. The first sub-circuit receives the Q signal, and the second sub-circuit receives the I signal. In one embodiment, to create the fractional transfer function, a multi-feedback looped integrator is used.

Abstract: A mixer for a radio transceiver includes a commutating mixer switch having a first differential input port coupled to a DC offset cancellation path. The first differential input port of the mixer switch includes a first terminal coupled to a first end of a first resistor and a second terminal coupled to a first end of a second resistor. Second ends of the first and second resistors are configured to receive a differential input signal. The DC offset cancellation path may provide a resistively coupled DC calibration signal for reducing the magnitude of DC offsets that may be present at the input of the mixer switch. The concept can be used for either image or non-image reject mixers.

Abstract: An image rejection mixer (IRM) for rejecting signals having image frequency and, more particularly, a mixer for rejecting signals of image frequency by using mismatch compensation is provided. The image rejection mixer comprises: first and second mixers; first and second converting means, each of which transforms each output of the first and second mixers to digital signal; third and fourth mixers, each of which mixes output of the first converting means with each of second local oscillation in-phase signal and quadrature-phase signal, respectively; fifth and sixth mixers, each of which mixes output of the second converting means with each of second local oscillation in-phase signal and quadrature-phase signal, respectively; means for subtracting; means for adding; and means for compensating gain-mismatch between the first and second mixers.

Abstract: Methods and apparatus for implementing image rejection in radio receivers or transmitters includes a Weaver image reject mixer modified so that only one local oscillator is used for the highest mixing frequency, and subsequent lower frequency mixing signals fed to the mixers are derived from digital frequency divider networks which produce both in-phase and quadrature versions of their pre-determined output frequencies. By using frequency dividers to generate these subsequent lower frequency signals, the intermediate frequencies walk; and when these frequency dividers are set to divide by multiples of two, generating quadrature signals becomes straightforward.

Abstract: Methods and apparatus, in accordance with the present invention, use at least two phase-locked loop based frequency synthesizers to provide a synthesized frequency output having a step size of X, where X is less than the step size of any of the at least two phase-locked loop based oscillators. By combining a first signal having a first frequency, with the output of a first frequency synthesizer having a first frequency step size, NX, to produce an intermediate signal which is in turn combined with the output a second frequency synthesizer having a second frequency step size, MX, an output signal is produced. M and N are related such that i times M=N±1, and i, M and N are integers. By varying the output frequency of the first and second frequency synthesizers, the frequency of the output signal is changed by steps of X, where X is less than the step size of either the first or second frequency synthesizers.

Abstract: A wireless receiver including a receive chain, a synchronization processor, a memory, a combiner and a soft decision processor. The synchronization processor determines a frequency response of the wireless channel using synchronization data transmitted in the wireless channel. The memory stores a compensation vector indicative of a frequency response of receive chain filtering. The combiner combines the compensation vector with the wireless channel frequency response to provide a compensated frequency response. The soft decision processor uses the compensated frequency response to evaluate data decisions. The compensation vector is based on measurement or estimation of the frequency response of the receive chain. The combiner may be based on multiplication or addition. The wireless receiver may include an FEQ. The synchronization processor generates FEQ coefficients for programming the FEQ taps.

Abstract: The present invention discloses an architecture for a concurrent dual-band high-frequency receiver. The invention combines a concurrent dual-band front-end subsystem having a dual-band antenna, dual-band pre-amplifier filter and concurrent dual-band LNA with a novel image rejection downconverter to provide the functions of a typical receiver, including reception, amplification and downconversion of a signal in two discrete desired frequency bands simultaneously.

Abstract: A superhet receiver in which an input signal is frequency down-converted in a first mixer (14) to produce a first IF signal comprising a wanted channel signal and an image channel signal. The first IF signal, without image rejection filtering, is frequency down-converted in a second mixer (24) to produce a second, lower IF signal comprising at least the wanted channel signal having a bandwidth corresponding to a predetermined passband of a channel filter (32) coupled to the output of the second mixer. The local oscillator signals used in the first and second frequency down conversion processes are varied in order to produce successively different image channel signals in the first IF signal and to maintain the wanted channel signal in the second IF signal within the passband of the channel filter (32).

Abstract: An RF communications circuit having a reduced LO feed through image reject mixer is disclosed. The image reject mixer includes a quadrature phase transconductance stage coupled to a quadrature phase mixer of a quadrature phase mixer module and an in-phase mixer of an in-phase mixer module. The image reject mixer further includes an in-phase transconductance stage coupled to an in-phase mixer of the quadrature phase mixer module and a quadrature phase mixer of the in-phase mixer module. The output of the quadrature phase mixer and in-phase mixer of the quadrature phase mixer module are cross-coupled to form a quadrature phase local oscillator (LO) output and wherein the output of the quadrature phase mixer and in-phase mixer of the in-phase mixer module are cross-coupled to form an in-phase local oscillator (LO) output.

Abstract: The invention relates to a frequency converter designed for supplying an output signal having a radio frequency FR equal to the difference between the frequency FLO of a signal OS originating from an oscillator VCO and the frequency FI of an input signal IS. The frequency converter has two quadratic modules QM1 and QM2 for separating the signal originating from the-oscillator OS and the input signal IS into two components (LO1, LO2) and (FI1, FI2) in phase quadrature, two mixers MX1, and MX2 for multiplying the components thus obtained two-by-two, and combination means COMB for recombining the output signals RS1 and RS2 of the mixers MX1 and MX2. The frequency converter operates internally a good rejection of the image frequency while providing a good performance as regards noise and gain and an improved linearity as compared with known converters. Thus, frequency shifting before transmission in a wireless telephone may be accomplished.