Abstract: The present invention is a controllable input impedance RF mixer, which when fed from a high impedance source, such as a current source, provides a high quality factor (Q) impedance response associated with an impedance peak. The high-Q impedance response may be used as a high-Q RF bandpass filter in a receive path upstream of down conversion, which may improve receiver selectivity and replace surface acoustic wave (SAW) or other RF filters. The present invention uses polyphase reactive circuitry, such as capacitive elements, coupled to the down conversion outputs of an RF mixer. The RF mixer mixes RF input signals with local oscillator signals to translate the impedance of the polyphase reactive circuitry into the RF input impedance of the RF mixer. The RF input impedance includes at least one impedance peak. The local oscillator signals are non-overlapping to maximize the energy transferred to the polyphase reactive circuitry.

Abstract: Systems and methods for demodulating a plurality of contiguous channels contained within a bandlimited portion of a radio-frequency (RF) input signal are provided. In an embodiment, the bandlimited portion of the RF input signal is down-converted to baseband. After down-conversion, the bandlimited portion overlaps at baseband with a mirror image of the bandlimited portion. The plurality of contiguous channels within the down-converted signal similarly overlap at baseband and subsequently occupy a bandwidth substantially equal to half that required before down-converting. Image rejection is performed in the digital domain to recover each of the plurality of overlapping channels.

Abstract: A digital direct conversion receiving apparatus, including: a phase conversion unit to down-convert a Radio Frequency (RF) signal into a plurality of sample signals, and generate a certain phase difference among the plurality of sample signals when the RF signal is down-converted; and a variable complex gain unit to remove an image component from the plurality of sample signals using the generated phase difference.

Abstract: The radio receiver includes: a mixer configured to convert a received signal to an IF signal using a local oscillation signal; an IF processing section configured to limit the band of the IF signal; a detection section configured to demodulate the band-limited IF signal; a frequency control section configured to output a frequency control signal corresponding to a desired signal; and a local oscillation section configured to generate the local oscillation signal having a frequency corresponding to the desired signal according to the frequency control signal. The frequency control section outputs as the frequency control signal to change the frequency of the local oscillation signal so that the difference from the frequency corresponding to the desired signal is not more than the frequency of the IF signal, and determines one of the set values with which the corresponding image signal strength is lowest as the frequency control signal.

Abstract: Input average levels and output average levels of digital channel filters 217 and 218 are computed in amplitude calculation circuits 101 and 102. In a gain difference calculation circuit 103, a gain difference of the input levels and the output levels is computed as a multiplier ? so that a difference between the input levels and the output levels are eliminated or adjusted to be within a certain value. The outputs of the digital channel filters 217 and 218 are multiplied by the multiplier ? in multiplier units 104 and 105. The multiplication results are outputted as corrected digital signals to a subsequent digital signal processing circuit.

Abstract: The present invention relates to a bidirectional frequency mixer, as well as a radiofrequency transceiver system including at least such a mixer. The mixer includes two ports separated in intermediate frequency FI, one for the reception, the other for the emission and a common port in frequency RF both for reception and for emission. It also includes at least fours mixing cells and three phase shifting means of signals used to remove the undesirable frequencies generated by the mixing cells. The mixer enables a rejection of the frequencies produced by a local oscillator in transmitting phase and a rejection of the image phase in receiving phase to be preformed. The invention is in particular applicable to designing microwave integrated circuits, in particular in millimetric frequency band.

Abstract: Systems and techniques relating to image cancellation in received communications signals are described. A described technique includes receiving a communications signal including a desired signal and an image signal; generating a leakage tracing signal at a frequency band of the image signal, the leakage tracing signal including a noise signal, a frequency of the leakage tracing signal being within the frequency band of the image signal; and removing the image signal from a signal that is based on the communications signal and the leakage tracing signal to resolve the desired signal, where the removing is based on an addition of the leakage tracing signal to the communications signal. Removing the image signal can include using one or more weights to control one or more filters to resolve the desired signal. The one or more weights can be determined based on the noise signal.

Abstract: Elimination of intermodulation interference in a wireless communication system by removing a portion of the spectrum of transmitted signals. According to a received indication of an occurrence of intermodulation interference experienced by a narrowband receiver, mappings are performed between the predetermined narrowband channel frequency on which the narrowband receiver operates and the occupied channel frequencies of at least one broadband transmit signal. Narrowband candidate frequency ranges that linearly combine into frequencies that overlap the predetermined narrowband channel frequency are determined based on the mappings. The narrowband candidate frequency ranges that potentially contribute to the intermodulation interference are then selectively filtered by at least one notch filter until the intermodulation interference is substantially eliminated.

Abstract: The employment of cascading in connection with improving mixer isolation in a Gilbert mixer circuit. 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: An orthogonal mixer generates first I and Q signals by down-converting an RF signal. A complex filter has an asymmetrical frequency gain property between a positive frequency domain and a negative frequency domain, and generates second I and Q signals by suppressing image signals included in the first I and Q signals compared with desired signals. An orthogonal compensation circuit is located at a subsequent stage of the complex filter, and corrects the second I and Q signals to cancel a phase difference error and an amplitude error of the desired signals between the second I and Q signals. Further, a control circuit adjusts an element characteristic of the complex filter to cancel a phase difference error and an amplitude error of the image signals that appear in the second I and Q signals.

Abstract: A wireless communication system receiver compensates a received signal containing an IQ gain imbalance prior to performing frequency correction. The IQ gain imbalance in the signal is estimated after frequency correction, providing an IQ gain imbalance estimate for subsequent IQ gain imbalance compensation. The IQ gain imbalance estimation includes formulating a plurality of hypotheses of phase error between I and Q signal components, and taking as the actual phase error the hypothesis that yields the maximum power ratio between I and Q signal components. The maximum power ratio is differentiated with respect to the IQ imbalance estimate. The IQ gain imbalance estimate is updated as a function of its prior value(s), the maximum power ratio, and the derivative of the maximum power ratio.

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: Aspects of a method and system for simultaneous signal transmission on multiple selected frequencies may include generating from a single baseband signal, a plurality of radio frequency transmission signals each at a different radio frequency, wherein the single baseband signal comprises an in-phase signal component and/or a quadrature signal component. The single baseband signal, to generate said plurality of radio frequency transmission signals, may be modulated in a single radio frequency transmission chain, the radio frequency transmission chain comprising intermediate frequency modulation and radio frequency modulation. The plurality of radio frequency transmission signals may be a radio frequency signal and a corresponding image frequency signal, based on the intermediate frequency modulation and the radio frequency modulation.

Abstract: A signal processing arrangement (REC) comprises a filter (PPF) with variable filter elements (FE). A switching circuit (SWCT) switches a filter element (FE1) and, subsequently, another filter element (FE3) from a filter state to an adjustment state and back again to the filter state. A filter element that is in the filter state contributes to a suppression of unwanted signals. A filter element that is in the adjustment state affects a characteristic of a measurement signal (Sm). An adjustment circuit (ADCT) adjusts the filter element that is in the adjustment state so that the characteristic of the measurement signal is substantially equal to a target value (TV).

Abstract: A mixer used in a Radio Frequency (RF) receiver is provided. The mixer includes a first harmonic rejecter for rejecting a harmonic signal component from a first input signal; and a second harmonic rejecter for rejecting a harmonic signal component from a second input signal. The first harmonic rejecter and the second harmonic rejecter are connected in parallel to reject an image signal component from the first input signal and the second input signal. Thus, the RF receiver can reject the harmonic signal and the image signal without using an external element.

Abstract: A method of processing an in-phase signal component and a quadrature signal component of a low intermediate frequency (LIF) signal includes estimating and correcting an amplitude imbalance between a digitized in-phase signal component and a digitized quadrature signal component at a first point in time, and estimating and correcting a phase imbalance between the digitized in-phase signal component and the digitized quadrature signal component at a second point in time in response to the correcting process. The digitized in-phase signal component corresponds to the in-phase signal component at the first point in time and the digitized quadrature signal component corresponds to the quadrature signal component at the first point in time. The second point in the time is subsequent to the first point in time.

Abstract: An image frequency rejection mixer has a first differential transconductor that receives a differential mixer input signal, a second differential transconductor that receives the differential mixer input signal and cross-coupled to the first differential transconductor, a first mixing circuit that generates a first differential mixing circuit output signal by mixing a first differential information signal with a first local oscillation signal, a second mixing circuit that generates a second differential mixing circuit output signal by mixing a second differential information signal with a second local oscillation signal, with the first local oscillation signal and the second local oscillation signal being in quadrature, and an image rejection circuit that generates a differential mixer output signal from the first and second differential mixing circuit output signals.

Abstract: Embodiments of a system for calibrating the image rejection of a receiver include an image-rejection correction circuit that modifies the gain and phase of a first channel of a baseband image signal. The image-rejection correction circuit may include a summing circuit and first and second variable-gain elements. In one implementation, a filter receives a corrected first channel from the image-rejection correction circuit and an unmodified second channel of the image signal, while a controller analyzes power measured at the output of the filter, and adjusts the variable-gain elements to reduce the power of the image signal.

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: A receiver (10) for extracting a desired signal component (70) from a received signal, which received signal contains the desired signal component (70) and may contain an interfering signal component (72), wherein the receiver (10) comprises a first mixer (16) which generates an intermediate frequency signal containing a frequency-shifted version of the received signal and a frequency-shifted version of an image of the received signal, the receiver further comprising: a second mixer (26) for shifting the desired signal component (70) of the intermediate frequency signal such that it is centred on a baseband frequency, so as to generate a first composite signal containing the shifted desired signal component (70) and a shifted version of any interfering signal component (76) contained in the image of the received signal; a third mixer (30) for shifting an image of the desired signal such that it is centred on the baseband frequency, so as to generate a second composite signal containing the shifted image (74)

Abstract: A semiconductor device interconnecting unit configured to input/output a high-frequency signal having a millimeter wave band to/from a semiconductor device is provided. The semiconductor or device interconnecting unit includes a part of a band pass filter configured to pass therethrough the high-frequency signal having a millimeter wave band by using an LC resonance circuit, and a remainder of the band pass filter, wherein the part and the remainder are separated from each other. The part is provided inside the semiconductor device, and the remainder is provided outside the semiconductor device. The part and the remainder include capacitors having variable capacitors added thereto, respectively. A pass band for the high-frequency signal having a millimeter wave band is changed by changing capacitance values of the variable capacitors.

Abstract: An integrated variable voltage diode capacitor topology applied to a circuit providing a variable voltage load for controlling variable capacitance. The topology includes a first pair of anti-series varactor diodes, wherein the diode power-law exponent n for the first pair of anti-series varactor diodes in the circuit is equal or greater than 0.5, and the first pair of anti-series varactor diodes have an unequal size ratio that is set to control third-order distortion. The topology also includes a center tap between the first pair anti-series varactor diodes for application of the variable voltage load. In preferred embodiments, a second pair of anti-series varactor diodes is arranged anti-parallel to the first pair of anti-series varactor diodes so the combination of the first pair of anti-series varactor diodes and the second pair of anti-series varactor diodes control second-order distortion as well.

Abstract: According to an example embodiment, an apparatus is provided in a wireless transceiver. The apparatus may include a circuit configured to generate a first frequency signal (e.g., a VCO signal). A local oscillator (LO) generator may be provided that includes a frequency divider to divide the first frequency signal, and an image rejection mixer configured to mix the first frequency signal with an output of the frequency divider to generate an LO signal. In this manner, the LO generator may generate a desired LO signal while substantially rejecting or suppressing an unwanted sideband or image signal, according to an example embodiment.

Abstract: Various embodiments are disclosed relating to Q-enhancement cells. According to an example embodiment, a circuit may include an inductor with a quality factor (Q), and a Q-enhancement cell coupled to the inductor. The Q-enhancement cell may include a current source having a variable bias current slope. Stability may, for example, be improved by providing a variable or programmable bias current slope for the Q-enhancement cell. In another example embodiment, a Q-enhancement cell may be used to compensate for Q degradation due to one or more switched capacitors in a circuit. The switched capacitors may be used, for example, for channel or frequency selection for the circuit. In another example embodiment, a Q-enhancement cell may be used to compensate for Q degradation caused by a transmission line.

Abstract: A system and method are provided for calibrating Amplitude Modulation to Phase Modulation (AM/PM) pre-distortion in a transmitter operating according to a polar modulation scheme. In general, phase modulation is disabled during transmission of an actual polar modulation signal. As a result, the transmitter provides a radio frequency (RF) output signal having an amplitude modulation component and ideally a constant phase. However, the AM/PM distortion of the transmitter creates a phase modulation component in the RF output signal. The phase component of the RF output signal, which is the AM/PM distortion of the transmitter, is measured by test equipment. The AM/PM pre-distortion applied by the transmitter is then calibrated based on the measured AM/PM distortion such that the AM/PM distortion of the transmitter is substantially reduced.

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 passive implementation of an image reject mixer (IRM), capable of operating at very high frequency, is operative according to the disclosed method. The IRM comprises a quad MOS multiplier and a lumped-element hybrid, resulting in a passive IRM. Operative at a radio frequency (RF) of tens of GHz with an intermediate frequency (IF) of several GHz. The RF+ and RF? signals are provided to two quad MOS multipliers. A local oscillator signal (LO) is used to provide LO+ and LO? signals to one of the multipliers and by providing the LO to a phase shifter, generated are a ninety degree shifted LO+ and LO? signals provided to the other multiplier. Providing the hybrids with the outputs of both multipliers and selecting an appropriate IF signal from each of the hybrids ensures the proper operation of the passive IRM.

Abstract: According to one embodiment, a method for updating filter values of an image canceller is provided. The method may include determining a channel-to-image (C/I) ratio between a channel signal and an image signal at the canceller input and generating a gain control value based at least in part on the C/I ratio. Then correlations between the channel signal and the image signal at the canceller's input and output can be generated, along with a gear control value based at least in part on a ratio between the correlations. In turn, one or more filters of the canceller can be updated using the control values.

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: A magneto-electric-induction conversion system of a wireless input device includes an emitter and a receiver. A plurality of serially-connected resonant circuits, arranged side by side, makes resonance, so transmission energy is enhanced. An electromagnetic wave is transmitted via an inductive antenna, then received and converted by predetermined parallel-connected resonant circuits into an available power source, so that the energy is effectively delivered.

Abstract: In a double-tuning circuit including a primary tuning circuit having a first inductor and a first variable capacitive element connected in parallel and a secondary tuning circuit having a second inductor and a second variable capacitive element connected in parallel, a fixed part of a copper-foil pattern is connected to a connection point at which the double-tuning circuit is connected to an input terminal of a frequency mixing circuit, and a tip part of the copper-foil pattern extends to near the first inductor, whereby a trap circuit for attenuating an image frequency component is formed. A pattern is formed between a ground-side terminal of the first inductor and the ground, and a capacitor is connected between a connection point at which the first inductor is connected to one terminal of the pattern and a ground-side terminal of the second variable capacitive element.

Abstract: A transmitter includes a first amplifier to amplify an in-phase oscillator signal to produce an in-phase mixing signal and a second amplifier to amplify a quadrature-phase oscillator signal to produce a quadrature-phase mixing signal. A first mixer mixes the in-phase mixing signal with a first information signal to produce a first output signal. A second mixer mixes the quadrature-phase mixing signal with a second information signal to produce a second output signal. The first output signal and an inverted second output signal are summed to produce a transmitter output signal that includes an image signal caused by a phase imbalance between the in-phase and quadrature-phase mixing signals. An image monitor monitors the image signal and reduces or eliminates the phase imbalance by independently adjusting a phase of the in-phase mixing signal and/or a phase of the quadrature-phase mixing signal. Consequently, a power of the image signal is reduced or eliminated.

Abstract: Adjacent channel interference (ACI) suppression is achieved by selectively applying one or more pre-calculated fixed filters only when necessary, thereby preserving the sensitivity of the receiver. An energy detector accurately detects adjacent channel interference in the frequency band of the desired signal so that the likelihood of a false detection of ACI is very low. If the energy detector detects adjacent channel interference is present in the band of the desired signal, then the received signal is selected to be filtered by the pre-calculated filter, e.g., a low pass filter. Otherwise, the pre-calculated filter is bypassed. In either case, additional ACI suppression processing may be employed.

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: An integrated receiver with channel selection and image rejection substantially implemented on a single CMOS integrated circuit is described. A receiver front end provides programmable attenuation and a programmable 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: A circuit and method for image frequency rejection is provided that includes an analog dual-quadrature mixer device whose signal inputs for an in-phase-signal and a quadrature-phase signal are connected to an input circuit in the signal path and whose oscillator inputs for an in-phase oscillator signal and a quadrature-phase oscillator signal are connected to a local oscillator device, having an analog adder-amplifier device, which has a number of transistor pairs, in which in each case both transistors of each transistor pair are connected to the same load resistor for the addition of the signals applied at the control inputs of both transistors, and in which the control inputs of both transistors are connected downstream of the outputs of analog dual-quadrature mixer device, and having a multistage analog polyphase filter whose inputs are connected to outputs of the adder-amplifier device.

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: 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: A receiver (1300) includes a mixing digital-to-analog converter (DAC) (1306), a direct digital frequency synthesizer (DDFS) (132A) and an interface (134D). The mixing DAC (1306) includes a radio frequency (RF) transconductance section (1308) and a switching section (1310). The RE transconductance section (1308) includes an input for receiving an RF signal and an output for providing an RE current signal. The switching section (1310) is coupled to the RF transconductance section (1308) and includes inputs for receiving bits associated with a digital local oscillator (LO) signal and an output that is configured to provide an analog output signal. The DDFS (132A) includes outputs configured to provide the bits associated with the digital LO signal to the inputs of the switching section (1310). The interface (134D) is coupled to the DDFS (132A) and is configured to align the bits provided by the DDFS (132A) with a first clock signal.

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: A FM-AM demodulator includes a FM signal amplifier, a local oscillator, an image oscillator, a first selector, a first orthogonal mixer, an AM signal amplifier, a first frequency divider, a second frequency divider, a second selector, a second orthogonal mixer, a third selector, a first filter, a first amplifier, a fourth selector, a second filter, a second amplifier, a first gain controller, an I/Q compensation unit, an IF oscillator, a third orthogonal mixer, an adder, a channel filter configured to extract a signal with a predetermined frequency band output from the adder, a third amplifier, a second gain controller, a demodulator, and an I/Q compensation controller configured to generate an I/Q compensation signal to use for adjusting phase and gain of the I signal used in an I/Q compensation unit by detecting amplitude of the output signal from the demodulator, and output the generated signal to the I/Q compensation unit.

Abstract: An adaptive wireless receiver and method thereof is disclosed in the present invention. The receiver includes an antenna, a bandpass filter, a front-end unit and a demodulator. Elements inside the front-end unit can be reused when the receiver operates in a zero intermediate frequency (ZIF) mode and in a low intermediate frequency (LIF) mode. The front-end unit includes a first and second down-conversion mixer, an analog filter, a first and second analog-to-digital converter (ADC), and a digital filter.

Abstract: A communication system for determining a target calibration parameter for calibrating impairments in a transmission signal is disclosed. The communication system includes a carrier signal generator, a transmitting module, a testing signal generator, a power detection unit, and a calibration apparatus. The testing signal generator generates a first testing signal to the first transmitting path of the transmitting module or a second testing signal to the second transmitting path of the transmitting module according to a single tone signal having a specific frequency or according to combinations of a DC value and the single tone signal. The power detection unit detects power of components associated with the specific frequency in the transmission signal to generate a power indicating signal. The calibration apparatus applies a first candidate calibration parameter to reference a first power indicating signal corresponding to the first candidate calibration parameter to determine the target calibration parameter.

Abstract: In a system and method for simultaneously receiving or switching between dual frequency carrier signals in a GPS receiver, the GPS receiver is adapted to utilize different harmonics of a sub-harmonic frequency generator, which may include a lower frequency voltage controlled oscillator (VCO) to detect the L1 and L2 GPS carriers. A sub-harmonic mixer may be used to simultaneously down convert the L1 and L2 signals to a lower intermediate frequency (IF). A second mixer may be an image reject (IR) mixer used to separate the downconverted L1 and L2 signals. This mixer may be configured to simultaneously monitor the L1 and L2 signals, or to switch between the L1 and L2 signals. High frequency switching is not required of the radio frequency (RF) input or local oscillator signals, and simultaneous L1 and L2 reception is enabled without and 3 dB image noise degradation.

Abstract: In one embodiment, a receiver includes parallel paths for signal channel processing and image channel processing. The paths may include a mixer to receive an intermediate frequency (IF) signal and to downconvert the IF signal to a channel baseband signal, a filter to generate a filtered channel value, a combiner to combine the channel baseband signal with a filtered channel value from the other path to obtain a channel path output, in addition to one or more controllers to generate a step control signal and update a weighting of the filters based at least in part on the step control signal.

Abstract: Systems and methods for interference cancellation in which a first signal having a first frequency may be cancelled with a second frequency having a second and different (e.g., lower) frequency by employing sampling to cancel the first signal with the separate signal at the sample instances.

Abstract: A method for mitigating interference from a switched-mode power supply begins by comparing a channel of interest of a plurality of channels with a switching rate of a switch-mode power supply. The method continues when the channel of interest compares unfavorably to the switching rate by adjusting the switching rate of the switch-mode power supply until the channel of interest compares favorably to the switching rate.

Abstract: A direct conversion tuner down-converts television signals, cable signals, or other signals directly from an RF frequency to an IF frequency and/or baseband, without an intermediate up-conversion step for image rejection. The direct conversion tuner includes a pre-select filter, an amplifier, an image reject mixer, and a poly-phase filter. The pre-select filter, amplifier, and the image reject mixer can be calibrated to provide sufficient image rejection to meet the NTSC requirements for TV signals. The entire direct conversion tuner can be fabricated on a single semiconductor substrate without requiring any off-chip components. The tuner configuration described herein is not limited to processing TV signals, and can be utilized to down-convert other RF signals to an IF frequency or baseband.

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: In a receiving apparatus comprising a quadrature mixer (5) for mixing a radio-frequency signal with a local oscillator signal to in-phase (I) and quadrature (Q) signal components at an intermediate frequency, a polyphase filter (9) for band pass filtering the IQ signal components, and an analog-to-digital converter (13) for converting the IQ signal components into digital form, and in which receiving apparatus adjacent channel interference may occur due to IQ signal component mismatching in the quadrature mixer (5), there is provided an adjacent channel rejection device connected between the quadrature mixer (5) and the polyphase filter (9). The device comprises an analog compensation circuit (33a; 33b; 33a-b) for compensating for the IQ signal component mismatching.