Abstract: A method is disclosed for performing dual mode image rejection calibration in a receiver. A first image correction factor is acquired for use in a receiver system using a first known signal associated with a first signal band during a startup mode. The first image correction factor is adjusted incrementally during a normal operation mode. A radio frequency (RF) signal associated with the first signal band is received using the first image correction factor during the normal operation mode.

Abstract: According to an aspect of the present invention, there is provided with a device control system including: an acquiring unit which acquires a BML document which can be delivered in digital broadcasting; a BML interpreting unit which interprets a description described in the BML document, for controlling an external device; and a communication unit which communicates with the external device on the basis of a result of interpretation by the BML interpreting unit.

Abstract: A center frequency of an adjustable filter is controlled to achieve a compromise between DC offset rejection and image rejection.

Abstract: There is disclosed a radio frequency (RF) demodulation circuit comprising: 1) a first RF mixer having a first input port for receiving an in-phase RF signal having a frequency of RF and a second input port for receiving an in-phase local oscillator (LO) signal having a frequency of LO, wherein LO is approximately equal to one-half of RF, and wherein the first RF mixer generates a first intermediate frequency (IF) signal having a frequency of LO; 2) a second RF mixer having a first input port for receiving an out-of-phase RF signal having a frequency of RF and a second input port for receiving an out-of-phase local oscillator (LO) signal having a frequency of LO, and wherein the second RF mixer generates a second intermediate frequency (IF) signal having a frequency of LO; and 3) a first signal combiner for combining the first and second IF signals to generate a composite IF signal, wherein the first signal combiner combines a first leakage signal from the first RF mixer and a second leakage signal from the se

Abstract: An apparatus and method for performing digital image correction in a receiver. In one embodiment, a receiver circuit may include an IQ signal source configured to provide a digital signal comprising in-phase (I) and quadrature (Q) components, such as an IQ mixer in combination with an analog to digital converter, for example. The receiver circuit may also include an image correction unit coupled to the IQ signal source and configured to combine the digital signal with a complex image correction factor. The image correction unit may be implemented using a digital signal processor under the control of associated program instructions, for example. In one specific implementation of the receiver circuit, the image correction unit may be configured to combine the digital signal with the complex image correction factor using a cross-accumulation operation.

Abstract: A disclosed method tunes a signal from a channelized spectrum having a predetermined channel spacing. A signal of interest having a predetermined maximum bandwidth is mixed with a local oscillator signal, which has a frequency that is an integer multiple of the channel spacing or one-half of a channel spacing displaced from an integer multiple of the channel spacing. The local oscillator signal is selected to frequency translate the signal of interest to within a near-baseband passband whose lower edge is spaced from DC by at least about the maximum bandwidth of the signal of interest. Problems associated with 1/f noise, DC offsets, and self-mixing products are avoided or substantially diminished. Other methods and systems are also disclosed.

Abstract: Methods and apparatus for automatic frequency control in wireless receivers configured to simultaneously receive multiple carrier signals at distinct radio frequencies are disclosed. An exemplary wireless device comprises at least first and second radio front-end circuits configured to receive first and second wireless communication signals transmitted via first and second radio-frequency carriers at distinct first and second radio frequencies, respectively, a control processor configured to designate a master carrier signal and a slave carrier signal from among the received wireless communication signals, and a frequency error estimation circuit configured to estimate a first receiver frequency error using the received master carrier signal. The control processor is further configured to calculate a second receiver frequency error from the first receiver frequency error, for use in compensating one or more receiver processes performed on the slave carrier signal.

Abstract: The invention enables a compromise between DC offset rejection and image rejection through the use of a bandpass filter having a variable center frequency.

Abstract: Certain embodiments of the invention may be found in a method and system for single sideband mixing receiver architecture for improving signal quality in an RF communication system. An embodiment of the invention may mix a first input signal with a first local oscillator signal, via a first mixer, to generate a first mixed output signal. It may also mix a second input signal with a second local oscillator signal, via a second mixer, to generate a second mixed output signal. It may then generate a single sideband signal by adding the first mixed output signal and the second mixed output signal. The removal of one of two sidebands may reduce noise at the desired signal, since the removed sideband may have been at the same frequency as the desired signal.

Abstract: A method and apparatus for trimming of a local oscillation within a radio frequency integrated circuit (RFIC) includes processing that begins when an RFIC receives a radio frequency (RF) signal having a known frequency. The processing then continues when the RFIC mixes the RF signal with a receiver local oscillation to produce a low intermediate frequency (IF) signal, which may have a carrier frequency of zero (i.e., a baseband signal) or up to a few mega Hertz). The processing then continues when the RFIC demodulates the low IF signal to produce demodulated data. The processing then continues as the RFIC determines a DC offset from the demodulated data, where the DC offset is reflective of the difference between the known frequency and the frequency of the receiver local oscillation. The processing then continues as the RFIC adjusts the receiver local oscillation to reduce the DC offset when the DC offset compares unfavorably with an allowable offset threshold.

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: Fast image rejection. Dual down conversion processing of a received signal by performing both low side injection and high side injection thereby generating a first down converted signal and a second down converted signal. Analysis of one or both of the first and second down converted signals, including the signal and image components thereof, is performed to determine which of the first down converted signal and the second down converted signal is appropriate to be selected for subsequent baseband processing. For example, if a signal strength of an image within the first down converted signal is less than a signal strength of a signal component within the first down converted signal, then the first down converted signal is most likely the appropriate signal to undergo baseband processing. Alternatively, if the converse is true, then the second down converted signal may be the appropriate signal to undergo baseband processing.

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 method in which one of a high-side mix mode and a low-side mix mode is selected in response to an interference characteristic of a desired channel of a radio frequency (RF) input signal is disclosed. In the high-side mix mode, a direct digital frequency synthesizer (130) is initialized to output a digital local oscillator signal at a first frequency suitable for performing a high-side mix of the desired channel to an intermediate frequency (IF). In the low-side mix mode, the direct digital frequency synthesizer (130) is initialized to output the digital local oscillator signal at a second frequency suitable for performing a low-side mix of the desired channel to said IF. The RF input signal is mixed with the digital local oscillator signal to provide an IF output signal at the IF.

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: A reception device includes a number of reception paths and a decoder. The reception paths are sequenced and each reception path includes a calculation module embodied to deliver a combined confidence index and a combined data stream, from the confidence index and the equalized data stream for the current path, as well as, for the subsequent reception paths after the first path, from the combined confidence index and the combined data stream, for the preceding path. The decoder is embodied to only process the combined confidence index and the combined data stream, provided by the calculation module in the last path.

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 communications receiver architecture characterized by a relatively low intermediate frequency (IF) and a polyphase filter. The receiver includes an input amplifier coupled to a carrier signal. Respective I and Q demodulators are coupled to the output of the input amplifier. A quadrature local oscillator (LO) generator provides respective LO_I and LO_Q inputs to the I demodulator and LO_Q inputs to the I demodulator and to the Q demodulator. The quadrature LO generator is driven by a phase-locked LO, and the LO frequency is such that an IF of, in one embodiment, approximately 1 MHz results. The I demodulator and Q demodulator outputs are applied through respective AID converters to a polyphase filter. The polyphase filter outputs are then processed by a digital I/Q demodulator.

Abstract: A device 20 includes a receiver 21 for receiving and processing signals at least in a first frequency band and an antenna 216 which is connected to the receiver 21. In order to improve the performance of such a receiver, the device 20 in addition includes a tuning component 217 for shifting a frequency response of the antenna 216 from the first frequency band to a second frequency band. Further, the device 20 includes a controlling portion 221 causing the tuning component 217 to shift the frequency response of the antenna 216 from the first frequency band to the second frequency band, in case a wideband noise is expected in the first frequency band. A corresponding method is shown as well.

Abstract: An RF receiver image rejection scheme. The RF is received and mixed in two quadrature channels allowing separation of the undesired image portion within the RF signal from the desired portion. The two channels can be summed to allow the image portions to cancel out and form a signal which is predominantly based on the desired portion. Another sum of the two channels can also be made to provide a signal which is primarily based on the image portion. Since there are some components of the image portion even in the compensated desired signal, that signal indicative of the image portion is used to compensate for that undesired portion.

Abstract: A spectrum analyzer is provided with frequency-scalable circuit architectures that extend the bandwidth of the spectrum analyzer using an array of couplers. The array of couplers is distributed along the RF signal path at one end, and interfaced to one or more frequency-translation devices such as mixers or samplers at the other. In a first architecture, a single mixer is employed with an LO signal applied to one input and coupler outputs providing RF signals to another input, with switching controlled to select one coupler's RF output to provide to the mixer. In a second architecture, a separate mixer is used, one for each coupler RF signal, with switches selecting one of the mixer IF outputs to select a desired output frequency. Both the first and second embodiments eliminate switching and its associated loss and frequency limitations from the main RF signal path to enable wideband high-dynamic-range spectrum analysis.

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 mixer produces an improved output signal during frequency translation of an input signal using a local oscillator (LO) signal. The mixer includes five component mixers connected in parallel. Each component mixer uses a phase-shifted version of the LO signal for frequency translation to produce a component output signal from the input signal. The component output signals are scaled according to corresponding gain factors and combined to form the output signal. When the mixer is used in a receiver, the phases of the component LO signals and the gain factors are configured to substantially cancel overlapping baseband versions of component input signals located at the third, fifth, seventh and ninth harmonics of the LO frequency. When used in a transmitter, the same phase and gain factor configurations substantially cancel third, fifth, seventh and ninth harmonics within the output 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 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 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 single conversion tuner suitable for receiving RF signals having different requirements as to selectivity, linearity and image rejection is presented. Tuners of this kind are particularly useful for digital terrestrial as well as cable reception, where different modulation schemes require very high image rejection ratios on one hand and high linearity or pass band flatness on the other hand. The inventive tuner features a double-tuned tuneable filter in combination with an image reject mixer. The double-tuned filter provides excellent pass band flatness, while the image reject mixer provides a high intrinsic image rejection. The image rejection ratio of the combination of image reject mixer and tuneable filter is very high and fulfils the requirements of commonly used modulation schemes such as 8VSB, while the pass band flatness is compliant with the requirements for modulation schemes such as QAM.

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: Methods and apparatuses for minimizing co-channel interference in communications systems are disclosed. A method in accordance with the present invention comprises scrambling a first frame using a first scrambling code, attaching a first header to the first frame to create the first signal, scrambling a second frame using a second scrambling code, attaching a second header to the second frame to create the second signal, and transmitting the first signal and the second signal over different channels of the communication system.

Abstract: The present invention relates to a detector device and, more particularly, to a detector device comprising a self-diagnosis means for monitoring the correct performance or otherwise of the device. During testing, the device, which normally operates using the Doppler shift principle, is arranged to influence the phase and/or amplitude of the received signal in response to an applied test signal. The received signal may be a Doppler shifted version of a transmitted signal. Combining the phase and/or amplitude shifted version of the received signal and the signal from the local oscillator produces an IF signal that is indicative of the phase and/or amplitude shift. If the device is operating correctly, that signal should have a predetermined range of characteristics. If the self-diagnosis means determines that the produced signal falls outside of the predetermined range of characteristics, an alarm is raised to alert, for example, maintenance personnel to the problem.

Abstract: An apparatus for generating an in-phase/quadrature-phase (I/Q) signal in a wireless transceiver is disclosed, including a local oscillator for generating an oscillation signal, and first and second mixers for mixing an oscillation signal with a transmission/reception signal to convert the transmission/reception signal into a baseband or high-frequency signal. The apparatus includes a phase locked circuit for controlling the local oscillator, and a polyphase filter installed between the local oscillator and the mixers, for separating the oscillation signal from the local oscillator into an I signal and a Q signal depending on a control signal from the phase locked circuit, and outputting the separated I and Q signals to the first and second mixers, respectively.

Abstract: A combined SAIC receiver and a multiple-antenna, receive diversity receiver are employed to reduce interference in a wireless system. The real and imaginary parts of the de-rotated signal for each receive path associated with an antenna are separately filtered and a combined output signal of all receive paths is generated. The weighting coefficients are adjusted based on an error signal produced by comparing the combined output signal with a reference signal. The weighting coefficients are initially set based on an MMSE/LS type of signal processing criteria, where the reference signal is the Training Sequence Code (TSC). Subsequent adjustment/tracking can be accomplished by using known tracking algorithms, e.g. LMS or RLS, or the coefficients can be re-computed using MMSE/LS processing. The reference signal for tracking may be a combination of the TSC and estimated data symbols provided by an equalizer.

Abstract: According to one embodiment of the invention, a system for controlling carrier leakage in a communications device is provided. The system includes a first mixer unit operable to receive a first signal, to convert the first signal into a second signal having a higher frequency than the first signal, and to transmit the second signal. The system also includes a second mixer unit. The second mixer unit is operable to receive the second signal, to convert the second signal into an in-phase signal and a quadrature signal each having lower frequency than the second signal, and to transmit the in-phase signal and the quadrature signal. The system also includes a processor coupled to the first mixer and the second mixer.

Abstract: An integrated receiver with channel selection and image rejection substantially implemented on a single CMOS integrated circuit is described. A receiver front end provides programable attenuation and a programable gain low noise amplifier. Frequency conversion circuitry advantageously uses LC filters integrated onto the substrate in conjunction with image reject mixers to provide sufficient image frequency rejection. Filter tuning and inductor Q compensation over temperature are performed on chip. The filters utilize multi track spiral inductors. The filters are tuned using local oscillators to tune a substitute filter, and frequency scaling during filter component values to those of the filter being tuned. In conjunction with filtering, frequency planning provides additional image rejection. The advantageous choice of local oscillator signal generation methods on chip is by PLL out of band local oscillation and by direct synthesis for in band local oscillator.

Abstract: An integrated semiconductor image-rejection mixer having high linearity and high gain. In addition to the components of a classic image-rejection architecture, the present mixer has a high-frequency current-diverting stage that permits the operation of the output stage with high conversion gain and sufficient headroom for good linearity, even in cases where the supply voltage is relatively low (such as 3 V). The conversion gain of the mixer and its image-rejection performance can be changed by changing the load resistances and the elements of the output polyphase network, with minor effects on linearity and no change in power consumption or DC levels. The power consumption of the image-rejection mixer is low because no additional DC current is required for buffers or amplifier stages.

Abstract: Methods and apparatuses for minimizing co-channel interference in communications systems are disclosed. A method in accordance with the present invention comprises shifting a characteristic of the first signal with respect to a like characteristic of the second signal to mitigate co-channel interference, and transmitting the first signal and the second signal over different channels of the communication system.

Abstract: A receiver (100) includes a mixing digital-to-analog converter (DAC) (120), a direct digital frequency synthesizer (DDFS) (116), and a clock circuit (114). The mixing DAC (120) includes a radio frequency (RF) transconductance section (124) and a switching section. The RF transconductance section (124) includes an input configured to receive an RF signal. The switching section (128) is coupled to the RF transconductance section (124) and includes inputs configured to receive bits associated with a digital local oscillator (LO) signal. The DDFS (116) includes outputs configured to provide the bits associated with the digital LO signal to the inputs of the switching section (128) and a first clock input configured to receive a first clock signal that sets a sample rate for the digital LO signal. The clock circuit (114) is configured to provide the first clock signal to the first clock input of the DDFS (116).

Abstract: The invention provides a system and method for tuning broadband signals by using post mixer I/Q equalization. An Image Rejection Mixer (IRM) is used for mixing Radio Frequency (RF) signals and rejecting image signals from the desired RF signals. The IRM includes an I/Q mixer and a filter. The I and Q paths resulting from the mixing operation in the I/Q mixer are equalized in amplitude and phase by an I/Q equalizer. Thereafter, the image signals are rejected from the desired RF signals using the filter.

Abstract: Systems for suppressing image noise are provided. In this regard, one embodiment includes a system for suppressing image noise comprising a low noise amplifier (LNA) configured to amplify a received RF signal, an RF variable gain attenuator with an image rejection filter with programmable bandwidth configured to suppress image noise and image interference, and an RF mixer configured to perform frequency translation.

Abstract: Image rejection calibration includes initializing the calibration mode by applying to quadrature mixers, in place of the wanted RF input, an RF source in the frequency range of the wanted RF input, sensing the power output from the poly-phase filter, developing gain adjust and phase adjust correction values in response to the power output and adjusting in accordance with the correction values the gain of the quadrature signals from the quadrature mixers to the poly-phase filter and the phase of local oscillator quadrature signals from the local oscillator to the quadrature mixers to reduce the power output.

Abstract: A Radio Frequency (RF) receiver includes a low noise amplifier (LNA) and a mixer coupled to the output of the LNA. The gain of the LNA is adjusted to maximize signal-to-noise ratio of the mixer and to force the mixer to operate well within its linear region when an intermodulation interference component is present. The RF receiver includes a first received signal strength indicator (RSSI_A) coupled to the output of the mixer that measures the strength of the wideband signal at that point. A second received signal strength indicator (RSSI_B) couples after the BPF and measures the strength of the narrowband signal. The LNA gain is set based upon these signal strengths. By altering the gain of the LNA by one step and measuring the difference between a prior RSSI_B reading and a subsequent RSSI_B? reading will indicate whether intermodulation interference is present.

Abstract: A mixer mixes respective signals of L1, L2C, and L5-E5a with a local oscillation signal where the frequency of the L1 signal has an image relationship with the frequencies of the L2C and L5-E5a signals to conduct frequency conversion. An image removal mixer mixes the respective position signals of 1stIF with a local oscillation signal where the frequency of the L1 signal of the 1stIF has an image relationship with the frequencies of the L2C signal and the L5-E5a signal of 1stIF to conduct frequency conversion. The image removal mixer then outputs the L1 signal of 2ndIF and the L2C and L5-E5a signals of 2ndIF, independently. A branching filter separates the L2C and L5-E5a signals of 2ndIF from each other, and outputs the separated signals.

Abstract: A receiver includes a tuning circuit for picking up a reception signal having a desired frequency, a local oscillator for forming an oscillation signal, a first mixer for frequency-converting the reception signal into an IF signal by using the oscillation signal, an IF filter for deriving the IF signal from an output signal of the first mixer, a signal forming circuit for forming an AC signal having a frequency equal to a frequency of the IF signal, a second mixer to be supplied with the AC signal and the oscillation signal, a deriving circuit for deriving a signal having a desired frequency or an image frequency from an output of the second mixer, and a detector for detecting a level of the IF signal, wherein a self test is performed by supplying the signal derived from the deriving circuit to the tuning circuit and checking a detection output level of the detector.

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: An impedance-matched IQ network includes a phase shift circuit and a back termination. The phase shift circuit includes an in-phase mixer port for receiving the in-phase signal, a quadrature-phase mixer port for receiving the quadrature phase signal, a termination port, and an output port. The back termination is coupled to the termination port of the phase shift circuit, the back termination having an impedance value substantially equal to the characteristic impedance of the phase shift circuit at the termination port.

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: A receiver circuit includes an oscillator circuit configured to generate a calibration tone and a phase locked loop (PLL) reference signal. An output frequency of the VCO may be divided by respective amounts to derive a desired calibration tone frequency and a desired PLL reference signal frequency. In addition to the oscillator circuit, the receiver circuit may further include a phase locked circuit configured to generate a PLL output signal that is phase locked in relation to the PLL reference signal. During a calibration mode, a quadrature generator may be used to generate quadrature mixer local oscillator signals dependent upon the PLL output signal, and an in-phase/quadrature mixer may be used to mix the calibration tone with the quadrature mixer LO signals.