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 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: A frequency upconverter using mixers operating on one or more signals and inverted versions thereof and a subtractor, such as a balun, for subtractively combining the mixer outputs to produce an upconverted signal.

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: A mixer arrangement includes a first mixer having at least one signal input for receiving a first signal the frequency of which is to be changed. The mixer arrangement also includes at least one frequency input for receiving an input frequency and at least one output. The first mixer is configured to mix a first signal with an input frequency to provide an output which is output by the at least one output. A second mixer has at least one frequency input for receiving an input frequency and at least one output. At least one output of the first mixer and at least one output of the second mixer are combined to cancel unwanted components from the input frequency in the outputs of the mixers.

Abstract: A signal generator for generating signals that are spaced ?/X rad apart, where X is an integer. The signal generator includes at least one delay cell with a delay that approximately corresponds to a phase shift ?/X rad for a given signal. The signal generator also includes at least one phase detection system receiving at least two signals with a phase difference of approximately ?/2 rad with respect to one another from said at least one delay cell and generating a feedback signal that is communicated to the at least one delay cell to adjust the phase relationship of the at least two signals. Such signal generators are used in radio frequency up-converters or down-converters.

Abstract: A multiple frequency RF communications receiver is disclosed which permits greater integration on standard silicon chips and consumes less power than previous receivers. A new method for selecting the various frequency bands with a high amount of isolation and low power consumption is described. Compared to previous receiver implementations, there is no loss of selectivity in the receiver.

Abstract: A Multi-Input/Multi-Output (MIMO) receiver may include a plurality of receiving antennas that receive a plurality of radio signals and an estimation section that finds channel estimation values of the plurality of radio signals. A MIMO separation section separates, using a MIMO scheme, the plurality of radio signals in accordance with the channel estimation values, and a compensation section compensates for channel variations of the plurality of radio signals. A selection section selects one of the MIMO separation section and the compensation section.

Abstract: The invention relates to a direct conversion receiver for down-converting a received multi-carrier signal comprising at least a first and a second carrier signal at image carrier frequencies to a base band resulting in that the first carrier signal includes an image signal of said second carrier signal. Further, the known direct conversion receiver comprises at least a first and a second digital down-converter unit for separating the first and the second carrier signal from the down-converted multi-carrier signal after digitization. In order to make such receivers less complex and adjust them for fast time varying szenarios it is proposed to provide an error estimating unit to said receivers for calculating a compensating coefficient representing the quota and/or the phase position of the image signal of the second carrier signal being included in the first carrier signal and to remove the undesired image signal in response to said compensating coefficient.

Abstract: The present invention provides methods and apparatuses for a polyphase filter, comprising: a first and second cascoded differential amplifiers configured to receive a first and second differential signals, the first cascoded differential amplifier having a first resistor coupled between current legs of the first cascoded differential amplifier and the second cascoded differential amplifier having a first capacitor coupled between current legs of the second cascoded differential amplifier; and a third and fourth cascoded differential amplifiers configured to receive said first and said second differential signals, the third cascoded differential amplifier having a second resistor coupled between current legs of the third cascoded differential amplifier and the fourth cascoded differential amplifier having a second capacitor coupled between current legs of the fourth cascoded differential amplifier; wherein the first and second cascoded differential amplifiers are configured to provide a first differential outp

Abstract: A low noise amplifier is provided for the receiver of a wireless communications system. The amplifier incorporates an image rejection function by incorporating a notch filter formed by an inductor and capacitor connected at a node between two active elements of the amplifier. The amplifier also incorporates a gain control function by adding a further active element connected to, on one hand, a node between the inductor and capacitor and, on the other hand, a voltage supply. A gain control signal is connected to the control input of the further active element has an input connected to a feedback lead of the receiver to provide the gain control.

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: A filter circuit includes a polyphase filter coupled to a first circuit component and a second circuit component. The first circuit component propagates four input current signals to the polyphase filter. The third and fourth input current signals are substantially one-hundred-eighty degrees out of phase with the first and second input current signals. The polyphase filter receives the input current signals and generates four output current signals that are out of phase with each other. The second circuit component generates first and second output signals using the four output current signals. The first and second output signals are ninety degrees out of phase with each other.

Abstract: A tuner is provided for selecting a channel from a broadband radio frequency input signal containing a plurality of channels, such as a terrestrial broadcast signal. The tuner has an input which supplies the broadband signal to a filter. The output of the filter is connected to a mixer of a single frequency changer, which converts the selected channel to a predetermined non-zero intermediate frequency. The filter is a tracking radio frequency filter which tracks the frequency of the selected channel so as to attenuate the image channel. A controller receives from a demodulator a signal representing reception quality, such as bit error rate, and adjusts the tracking of the filter so as to achieve acceptable reception quality, such as an adequately low bit error rate. Alignment of the filter during manufacture is not, therefore, required.

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: In a communications receiver for quadrature demodulation, a feedback technique for reducing the image response of the receiver. The communications receiver includes an I demodulator and a Q demodulator. A local oscillator (LO) signal is provided by a PLL to a quadrature LO generator that provides an LO_I signal to an I demodulator and an LO_Q signal to a Q demodulator. The LO_I and LO_Q signals are amplitude and phase-controlled versions of the LO signal. An image/signal ratio (I/S) detector detects the relative phase difference and the relative amplitude difference between the respective output terminals of the I demodulator and the Q demodulator and applies an amplitude control signal and a phase control signal to corresponding amplitude control and phase control inputs of the quadrature LO generator. The I/S detector calibrates the quadrature LO generator during the interstitial interval between the reception of data packets.

Abstract: Frequency translation, such as frequency up conversion of a video baseband or intermediate frequency to a desired frequency division broadcast channel, is provided utilizing a single sideband or image reject mixer and filtering having relaxed selectivity requirements. According to a preferred embodiment, a first single sideband mixer accepts an input signal at an intermediate frequency and up converts this signal to a high intermediate frequency. The image rejection provided by the single sideband mixer in combination with simple filtering provide sufficient signal quality to achieve desired levels of desired signal isolation, such as on the order of 40 dB. Preferably, a second single sideband mixer accepts the high intermediate frequency signal and down converts this signal to a desired transmission or broadcast frequency.

Abstract: A method and apparatus for enhancing signal quality within a wireless receiver are disclosed. An image of a desired signal is down-converted to a baseband signal by a digital down converter. The energy of the baseband signal is subsequently determined. If the energy of the baseband signal is equal to or greater than a predetermined threshold, then the IF is swapped for any incoming signals. If the energy of the baseband signal is less than the predetermined threshold, then the IF is maintained for any incoming signals.

Abstract: An apparatus and method for deriving a digital image correction factor in a receiver. In one embodiment, a receiver circuit may include an error detection circuit configured to receive a digital signal comprising in-phase (I) and quadrature (Q) components and to detect an error in a complex image correction factor, and an error correction circuit coupled to the error detection circuit and configured to modify the complex image correction factor dependent upon the detected error. In one specific implementation of the receiver circuit, the error detection circuit and the error correction circuit may be coupled in a feedback loop, where the error detection circuit may be configured to iteratively detect the error in the complex image correction factor, and where the error correction circuit may be configured to iteratively correct the error.

Abstract: There is disclosed a receiver which solves such a problem as to strictly realize channel selection filter characteristics in extracting a narrow band signal from a broad band signal by digital signal processing in a conventional direct conversion circuit and which improves an image rejection ratio and which can reduce a load of hardware or processing to realize a channel selection filter for extracting the narrow band signal. In a digital signal processing section, one set or a plurality of sets of an image rejection section, a frequency conversion section, and a rate conversion section are continuously connected. A narrow band signal of a desired wave is extracted from a broad band signal whose sampling frequency is lowered, and an offset provided at a local oscillator at the time of quadrature detection is removed in the receiver.

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 radio frequency (RF) demodulation circuit comprising a harmonic rejection mixing stage capable of receiving and mixing an incoming radio frequency (RF) signal having a frequency RF and a reference local oscillator (LO) signal having a frequency LO and generating an output signal in which out-of-band harmonic signals are suppressed. The harmonic rejection mixing stage comprises 1) a multiphase local oscillator (LO) generator for receiving the reference LO signal and generating M phase-shifted local oscillator signals having frequencies LO and 2) M mixers, each of the M mixers receiving the incoming radio frequency signal and one of the M phase-shifted local oscillator signals. Each of the M mixers generates a subcomponent signal. The subcomponent signals are then scaled and combined to produce the output signal.

Abstract: A reception frequency band is selected at 11.7 GHz–12.2 GHz, the local oscillating frequencies of local oscillators are determined at 10.75 GHz and 13.85 GHz, respectively, and each intermediate frequency band is selected at 950 MHz–1450 MHz and 1650 MHz–2150 MHz, respectively, so that the harmonic component of the frequency difference between local oscillation signals output from each local oscillator is not present in the frequency band of each intermediate frequency signal output from each mixer and in the reception band of polarization signals applied to input terminals.

Abstract: A multiband receiver and associated method are provided for simultaneous reception of a number of RF signals with partially different carrier frequencies. An RF/IF converter is provided with a number of local oscillators corresponding to a number of RF signals in order to produce L0 in phase components corresponding to the carrier frequencies and quadrature components; in addition to an in-phase mixer and a quadrature mixer for mixing the respective L0 in-phase and quadrature components with the RF signals in order to produce intermediate frequency signals with IF in-phse components and IF quadrature components. A complex fiber carries out complex filtering on the basis of the intermediate frequency signals in order to suppress reflected intermediate frequency signals.

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 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: An exemplary embodiment of the present invention described and shown in the specification and drawings is a transceiver with a receiver, a transmitter, a local oscillator (LO) generator, a controller, and a self-testing unit. All of these components can be packaged for integration into a single IC including components such as filters and inductors. The controller for adaptive programming and calibration of the receiver, transmitter and LO generator. The self-testing unit generates is used to determine the gain, frequency characteristics, selectivity, noise floor, and distortion behavior of the receiver, transmitter and LO generator. It is emphasized that this abstract is provided to comply with the rules requiring an abstract which will allow a searcher or other reader to quickly ascertain the subject matter of the technical disclosure. It is submitted with the understanding that it will not be used to interpret or limit the scope or the meaning of the claims.

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: The invention provides a harmonic direct conversion mixer having a multiplier circuit comprising first and second mixers and a generator for generating two first and two second control signals for controlling the first and second mixers. The control signals are balanced signals and are provided in four phases shifted by ?/2 in phase. The frequency of the control signals is different from the frequency of the mixer input signal.

Abstract: A mixer circuit can suppress image interfering signals and interfering signals related to higher harmonic component of an oscillator. Using the mixer circuit, it is possible to provide a high-frequency signal receiver which maintains good signal receiving condition. This mixer circuit comprises a plurality of mixers, oscillators, a plurality of oscillator phase shifters which serve to phase-shift the output of the oscillators and supply the output to the mixers, and a plurality of intermediate frequency phase shifters which serve to phase-shift the output of the mixers. The high-frequency signal receiver comprises at least a pre-filter and the mixer circuit.

Abstract: A single conversion tuner is provided for receiving digital terrestrial broadcast signals. The tuner comprises a single frequency changer comprising a mixer and local oscillator controlled by a PLL synthesiser. A non-alignable variable low pass filter is provided between the tuner input and the mixer, which is of the image reject type. The bandwidth of the filter is varied so as to track the local oscillator frequency to provide sufficient attenuation of the image channel without requiring any alignment during manufacture.

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: A receiver for rejecting an image signal is provided that does not require a phase-shifter and that requires less mixers than prior receivers. Thus, the phase imbalances and gain mismatches imparted by phase shifters are avoided, and harmonics due to non-liner effects in the mixers are reduced.

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: A mixer circuit with image frequency rejection comprising a quadrature phase divider (30, 30?) presenting an input connected to the input (Fi) of the mixer circuit and two outputs respectively delivering two signals in phase quadrature which are applied respectively to two simple mixers (31, 32; 31?, 32?), said mixer circuit comprising a quadrature phase and frequency divider (33, 33?) having a frequency division ratio and presenting two inputs respectively connected to the respective outputs of the two simple mixers (31, 32; 31?, 32?) and a first output delivering a first output signal (Fo) of the mixer circuit, which signal is applied to the inputs of the two simple mixers.

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: Disclosed is a method and apparatus of transmit diversity that is backward compatible and does not significantly degrade performance in additive white guassan noise (AWGN) conditions using a transmission architecture that incorporates a form of phase sweep transmit diversity (PSTD) referred to herein as biased PSTD. Biased PSTD involves transmitting a signal and a frequency swept version of the same signal over diversity antennas at different power levels. By transmitting the two signals at different power levels, the depths of nulls normally seen in AWGN conditions when PSTD is utilized is reduced and performance degradation in AWGN conditions is mitigated.

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 a 3 dB image noise degradation.

Abstract: An image rejection mixer of reduced power dissipation includes a signal distributor supplied with local signals having a phase difference to distribute the local signals, a first and a second signal mixer for mixing the distributed local signals and RF signals having a phase difference and outputting respective IF current signals, a phase shifter for shifting in phase the respective mixed IF current signals so as to provide them with a relative phase difference of 90 degrees, and a signal adder for adding the respective phase shifted intermediate frequency current signals. The shifter shifts the phases of the respective IF current signals outputted from the first and the second signal mixers.

Abstract: A filter circuit includes a polyphase filter coupled to a first circuit component and a second circuit component. The first circuit component propagates four input current signals to the polyphase filter. The third and fourth input current signals are substantially one-hundred-eighty degrees out of phase with the first and second input current signals. The polyphase filter receives the input current signals and generates four output current signals that are out of phase with each other. The second circuit component generates first and second output signals using the four output current signals. The first and second output signals are ninety degrees out of phase with each other.

Abstract: An image suppression filter circuit comprises a first phase shifter outputting a first output signal and a second output signal substantially orthogonal thereto, a second phase shifter outputting a third output signal and a fourth output signal orthogonal to the third output signal, a first subtracter subtracting the fourth output signal from the first output signal, a first adder adding the second and third output signals, a third phase shifter outputting a fifth output signal and a sixth output signal orthogonal to the fifth output signal, a fourth phase shifter outputting a seventh output signal and an eighth output signal orthogonal thereto, a second subtracter subtracting the eighth output signal from the fifth output signal, and a second adder adding the sixth and the seventh output signals.

Abstract: An image rejection mixer includes an input terminal for receiving an input radio frequency (RF) signal, a mode selector coupled to the input terminal generating an output signal for either high side mixing or low side mixing, a first mixer coupled to receive the input RF signal and a signal from a local oscillator providing a signal having a local oscillator frequency, a phase converter coupled to convert the phase of the signal from the local oscillator, a second mixer coupled to receive the output signal from the mode selector and the phase-converted local oscillator signal, and a tunable polyphase filter coupled to receive output signals from the first mixer and the second mixer, the tunable polyphase filter providing an output signal having a variable intermediate frequency. In one embodiment, the variable intermediate frequency the tunable polyphase filter is implemented as a switchable intermediate frequency.

Abstract: A ring oscillator produces an in-phase and quadrature phase radio frequency signal. A first mixer mixes the in-phase signal with a received signal. A second mixer mixes the quadrature phase signal with the received signal. A combiner, operatively coupled to the first and second mixers, produces an image cancelled signal.

Abstract: Disclosed are methods, systems, and a device that includes an output for providing at least a first signal at a first frequency and a distinct second signal at a distinct second frequency, a first signal channel connected between a first waveguide port and the output, the first waveguide port providing a harmonic of the first signal, and, a distinct second signal channel connected between a second waveguide port and the output, the second waveguide port providing a harmonic of the second signal, where the first signal channel includes a notch filter centered substantially at the distinct second frequency, and the second signal channel includes a notch filter centered substantially at the first frequency.

Abstract: Tunable upconversion mixers that have a controllable passband response and provide substantial image rejection, making costly post-mixing filtering at least optional, if not unnecessary for many applications. A single mixer is able to support several frequency bands (and/or be accurately tuned within one frequency band) by means of varying the capacitance in a tunable load circuit for the mixer circuit. The tunable mixer comprises a mixer circuit having inputs for receiving a signal to be upconverted and an oscillator signal to be mixed with the signal to be upconverted. The mixer generates a mixer output signal at a desired sideband frequency and an image signal at an image frequency.

Abstract: A novel RF to IF converter operates in two modes allowing both wide bandwidth signals and narrow bandwidth signals to be processed using the same wide bandwidth bandpass filter as well as a dual-mode image-reject mixer. As a mobile receiver, both wide bandwidth WCDMA or IMT-2000 signals and narrow bandwidth GSM signals pass through the same wide bandwidth channel select filter. In the GSM mode, signals lying to one side of the frequency range of the narrow GSM signal are attenuated by the wide bandwidth channel select filter. Then signals lying to the other side of the GSM signal are attenuated by an image-reject mixer. The image-reject mixer also downconverts the GSM signal. In the WCDMA or IMT-2000 mode, the wide bandwidth channel select filter attenuates signals outside of the WCDMA or IMT-2000 channel bandwidth, and the image-reject mixer downconverts the wide bandwidth signal without rejecting signals.

Abstract: The invention relates to an anti-demodulator circuit which is fundamentally built up in the same way as a demodulator circuit but, instead of a bandpass filter as generally used in a demodulator, comprises a notch filter which receives an input signal comprising a useful signal and an interference signal, and generates a filtered signal. The notch filter has a center frequency which approximately corresponds to the frequency of the input signal so as to suppress at least a part of the useful signal. The anti-demodulator circuit further comprises a mixer circuit which receives the filtered signal and a phase-shifted input signal and supplies a demodulated output signal which substantially corresponds to the interference signal.

Abstract: A phase interpolation receiver for receiving angle modulated radio frequency signals. The receiver comprises mixers for down-converting the received angle modulated signal to lower frequency signals, limiters, interpolation filters, and a demodulator. The mixers down-convert the received RF signal to a low IF intermediate frequency signal. The low IF intermediate frequency signal is limited. After further down-conversion to zero IF, using quadrature mixers, the limited signal is phase interpolated. The intermediate frequency is chosen such that the limited signal comprises an unwanted signal at twice the intermediate frequency that acts as a noise spreading signal for spectrally spreading of quantization noise generated by the limiters, and the cut-off frequency of the interpolation filters is chosen such that the unwanted signal and the spread quantization noise are suppressed.

Abstract: Described herein is a method and apparatus for transmission that provides the performance of space time spreading (STS) or orthogonal transmit diversity (OTD) and the backwards compatibility of phase sweep transmit diversity (PSTD) without degrading performance of either STS or PSTD using a symmetric sweep PSTD transmission architecture. In one embodiment, a pair of signals s1 and s2 are split into signals s1(a) and s1(b) and signals s2(a) and s2(b), respectively. Signal s1 comprises a first STS/OTD signal belonging to an STS/OTD pair, and signal s2 comprises a second STS/OTD signal belonging to the STS/OTD pair. Signals s1(b) and s2(b) are phase swept using a pair of phase sweep frequency signals that would cancel out any self induced interference. For example, the pair of phase sweep frequency signals utilize a same phase sweep frequency with one of the phase sweep frequency signals rotating in the opposite direction plus an offset of ? relative to the other phase sweep frequency signal.