Abstract: A tunable voltage controlled bandpass filter for a direct conversion receiver. A phase locked loop uses the phase change imparted by the bandpass filter to local oscillator breakthrough from the mixer for a measure of frequency difference between input RF and local oscillator output. An error voltage derived from the measured phase change is applied as a tuning control to the bandpass filter. A sample and hold arrangement allows disconnection of the tuning circuit for power saving. The filter is suitable for implementation as an integral part of an ASIC receiver.

Abstract: An active mixer circuit, and an associated method, includes a feedback element which increases the linearity of the mixer circuit so that the mixer circuit is operable over a wider dynamic range than typically permitted of conventional, active mixer circuits. The mixer circuit includes a transconductance stage including a pair of transconductance transistors. Signals are applied through both of the transconductance transistors in parallel. The feedback element is coupled to an output side of a first of the transconductance transistors. And, a mixing stage is coupled to an output side of a second of the transconductance transistors.

Abstract: In one embodiment, an apparatus comprising a mixing network coupled to a summing stage is presented. The mixing network is operative to receive a signal and process the received signal along a first branch of the mixing network to produce a first mixed signal containing an image signal, and along a second branch of the mixing network to produce a second mixed signal containing the image signal and a desired signal. The summing stage, coupled to the first and second branch of the mixing network, is operative to subtract the first mixed signal from the second mixed signal to produce a downconverted signal comprising the desired signal while rejecting the image signal.

Abstract: A method and apparatus for improving the sensitivity of a radio frequency (RF) receiver at certain frequencies suffering from co-channel interference. In the preferred embodiment, when a reference frequency, FREF, generates significant harmonics for a received RF signal in a selected channel, the reference frequency is varied or offset by a small amount, &Dgr;F. The harmonics of the offset reference frequency, F′REF=FREF±&Dgr;F, are thereby shifted away from the frequency of the received RF signal, thus reducing co-channel interference. The offset amount &Dgr;F is chosen such that the same injection frequency synthesized from FREF can still be synthesized from FREF±&Dgr;F by shifting N by an integer amount, preferably to N+1 or N−1. However, the invention encompasses shifting N by other integer amounts.

Abstract: A method for reducing the level of an undesired signal, generated through a frequency converter device, by implementing a local oscillator (hereinafter "LO") leak cancellation circuit. A feedback correction loop, for a radio frequency (RF) transmitter or receiver, reduces an undesired local oscillator leak generated through a single input frequency converter device, such as a mixer, by a unique detection circuit. A unique nulling circuit is also implemented for a multiple input frequency converter device, such as a quadrature modulator.

Abstract: A radio receiver, and a method therefore, for efficiently suppressing attenuation properties of a low frequency signal, in an analog frequency modulation type radio communication system. The radio receiver includes a first down-converter for mixing a modulated, high-frequency signal received by the radio receiver and a predetermined local oscillating signal to generate an intermediate frequency signal. A modulator modulates the predetermined local oscillating signal by an aural signal transmitted from the transmitter and generates a mixing signal for down-mixing the electrical signal representative of modulated, high-frequency signal. The mixed signal is then applied to the first down-converter. A second down-converter down-converts, in frequency, the intermediate frequency signal generated from the first down-converter into a baseband signal to generate the down-converted signal.

Abstract: The invention provides a superheterodyne receiver by which undesired radiations are minimized. The superheterodyne receiver includes a voltage-controlled oscillator for forming an oscillation signal of a frequency equal to n times a carrier frequency of an object FM signal, and a frequency divider for dividing the frequency of the oscillation signal to the carrier frequency. The superheterodyne receiver further includes a pair of first mixers for frequency converting the object received signal into a pair of first intermediate-frequency signals using signals from the frequency divider as a first local oscillation signal, and a pair of second mixers for converting the first intermediate-frequency signals into a second intermediate-frequency signal with the second local oscillation signals. The superheterodyne receiver further includes a demodulator for demodulating the second intermediate-frequency signal into an original signal.

Abstract: A DBS tuner for satellite broadcasting receivers, includes an attenuating filter (trap circuitry) composed of a microstrip line having an open-ended load terminal which projects from the RF signal line or the power supply line.

Abstract: A signal processing circuit for use in a mobile radio equipment terminal including a receiver is provided with an oscillator for oscillating a clock signal serving as a reference; a harmonic-component reducing circuit for restricting a level of harmonic components of the clock signal; and a CPU core portion for effecting signal processing by using the clock signal as a reference.

Abstract: A quadrature downconversion stage in a radio frequency receiver compensates for leakage from the quadrature local oscillator to the input of the stage by deriving first and second feedback signals from the quadrature local oscillator. The first feedback signal is 180.degree. out of phase with the in-phase component of the signal supplied to the input of the stage and the second feedback signal is 180.degree. out of phase with the quadrature component of the signal supplied to the input of the stage. The invention reduces or cancels a d.c. offset that can appear at the output of the stage. Another advantage is the reduction of re-radiated signals resulting from the local oscillator leakage. The invention is particularly applicable to direct converters.

Abstract: An arrangement for reducing interference in tuned circuits in integrated circuits as a result of the reception and transmission of high frequencies. An external tuned circuit is integrated in the integrated circuit and the interference which is otherwise produced by the connecting pins is eliminated.

Abstract: Mini-microstrip and mini-coplanar transmission lines are formed on a ship substrate with two metal layers. Together with a ground plane on the underside of the substrate, the lines are connected to form a Marchand balun. Two baluns, a quarter-wave transmission line and a diode quad are combined on a chip to form an MMIC mixer, and a par of mixers are combined with 90.degree. and 180.degree. splitters to provide circuits with superior rejection of specific spurious signals as well as RF and LO leakage over.

Abstract: In an electronic apparatus including a reference oscillator and an interfering part that generates an interference signal having a spectral component within a receiver bandwidth, the reference oscillator supplying a reference oscillating signal to the interfering part from which reference oscillating signal the interference signal is derived, amplitude of the interference signal within the receiver bandwidth is reduced by angle modulating the reference oscillating signal with a sinusoidal signal to generate an angle modulated interference signal having a reduced carrier amplitude and modulation sidebands that are outside of the receiver bandwidth. The angle modulated interference signal preferably has a modulation index, .beta., that is close to a solution of the equation J.sub.0 (.beta.)=0, where J.sub.0 is a Bessel function of the first kind.

Abstract: In order to further suppress unwanted waves which may occur when the frequency (flo) of a local oscillation wave is lower than the frequency (fin) of a signal wave, the local oscillation wave is in-phase distributed between unit mixers (2a) and (2b) whereas the signal wave is opposite-phase distributed through a 180 degree distributer (4) to the unit mixers (2a) and (2b). The unit mixers (2a) and (2b) execute frequency mixing of thus distributed local oscillation wave and signal wave, and supply the result through a BRF (16a) or (16b) into a 180 degree combiner (6). The 180 degree combiner (6) effects an opposite-phase combination of outputs of the BRFs (16a) and (16b), and outputs the result.

Abstract: A homodyne radio receiving apparatus is provided for mitigating fixed or variable DC offsets produced by residual second order intermodulation terms due to unwanted signals. The homodyne radio receiving apparatus includes an antenna, an antenna by-pass filter, an RF amplifier and a quadrature downconverter. The quadrature downconverter for the complex base band is centered around a desired reception frequency so that the complex baseband signals lie around zero frequency. A supplementary total power detector is provided to measure the total received power through the antenna by-pass filter so that the unwanted terms caused by second order intermodulation are compensated. The compensation is achieved by feeding instantaneous power measurements to a signal processing unit along with the complex baseband signals. The signal processing unit then determines a complex compensation coefficient by correlating the power signal with the complex baseband signals.

Abstract: In a homodyne receiver for the reception of a carrier frequency signal with time-variant carrier frequency, an auxiliary signal is modulated onto the local oscillator signal selected corresponding to the current carrier frequency. A better separation of the local oscillator signals is thereby achieved by a band-pass filtering after the conversion of the carrier frequency signal into the base band. Compared to a homodyne receiver with time-variant carrier frequency but without auxiliary modulation, the RF switch for the selection of the local oscillator signal corresponding to the current carrier frequency can be realized simple and more economical. This advantage of the homodyne receiver is of particular economic significance for employment in mass-produced articles, such as in mobile and wireless communication systems.

Abstract: There is provided a tuner capable of improving reliability thereof with reduced power consumption and reduced heat generation. In the tuner, one wideband amplifier circuit including one transistor constitutes a buffer amplifier. The wideband amplifier circuit is coupled with a first local oscillator circuit in a DC coupling style. With the above-mentioned arrangement, the buffer amplifier is allowed to have a simplified circuit construction and reduce noises. Since the amplifier circuit and the local oscillator circuit are coupled with each other in a DC coupling style, reduced power consumption can be achieved.

Abstract: A multiple conversion receiver system capable of avoiding receiver spurs by combined switching of multiple local oscillator frequencies, including combinations of high-side and low-side injection and IF shifting.

Abstract: A dielectric resonator image reject mixer and method comprises an amplifier for amplifying a receive frequency (RF) signal and outputting a first combined signal comprising a RF signal, a RF noise signal, and an image noise signal. A dielectric resonator image rejector is coupled to the amplifier. The dielectric resonator image rejector receives the first combined signal but outputs only a second combined signal comprising the RF signal and the RF noise signal to a mixer coupled to the dielectric resonator image rejector. The image noise signal is rejected by either reflection or resonant transmission to a resistor-terminated microstrip line. A mixer mixes the combined RF signal and the RF noise signal from the dielectric resonator image rejector with a local oscillation frequency signal, producing an intermediate frequency output signal.

Abstract: A semiconductor device including a plurality of interconnected functional blocks of integrated circuits, which include at least an amplifier block, the blocks operating at high and ultrahigh frequencies and having different frequencies with each block comprising at least a DC distribution line. Each block is polarized by the DC voltage of its distribution line and the blocks also include power-matched circuits operating in the ultrahigh frequency range. All of the high frequency and ultrahigh frequency functional blocks are integrated on one and the same substrate for realising the DC supply of all functional blocks at one and the same DC voltage value by one and the same DC voltage distribution line which is common to all the blocks. This is achieved, at least in part by the provision of frequency stabilization circuits for each individual functional amplifier block and also for the common DC distribution line, as well as autopolarization circuits for polarizing each block from the single DC voltage.

Abstract: A feed network parallel superconductive tunnel junction circuit that acts as a doubly balanced mixer and can be utilized as a millimeter wave satellite communications link. A quadrature-fed mixer circuit relies on a network of 90 degree couplers to feed signal and local oscillator power to four identical SIS detectors where SIS is a superconductor-insulator-superconductor layer construction. Power applied to either port is split equally to each detector, and the relative phase relationship of the signal and the LO is preserved. By selecting the appropriate polarity of the dc junction bias, the detected IF output of the SIS detectors adds coherently.

Abstract: A radio (100), powered by a battery (170), can be used in remote meter reading applications. In order to conserve battery power, the radio (100) is capable of determining that a signal is an image signal rather than a signal on the desired frequency. This is accomplished by attempting to receive a signal utilizing different local oscillator signals (high side injection and low side injection). If a signal is present, as indicated by the received signal strength with both local oscillator signals, then the radio (100) will attempt to decode data. The radio (100) does not attempt to decode data when the signal is determined to be a spurious signal. The radio (100) can then be operated in a reduced power consumption mode. This results in battery savings for radios operating in the presence of an image frequency signal.

Abstract: In a tuner unit including an antenna input filter section, a UHF section, a VHF section, and a PLL section which are electromagnetically separated by walls, an inductor for a VHF local oscillator is disposed adjacent to the UHF section, and is electromagnetically separated by a subdivision wall from the UHF section and the VHF section.

Abstract: A first PLL 15 circuit connected to a first local oscillator 4 and a second PLL circuit 18 connected to a second local oscillator 10 are disposed in a same casing 20, and it is therefore not necessary to issue the output signal of the second local oscillator 10 or the divided output signal of the first local oscillator 4 outside of the casing 20, so that generation of undesired harmonic interference due to adverse effects of distribution thereof may be eliminated, thereby obtaining a favorable reception state.

Abstract: A mixer is provided having a mixing element, an input signal port for incoming signals at a frequency f.sub.IN, a local oscillator signal port for signals from a local oscillator having a fundamental frequency f.sub.LO, and an output port from which the resultant frequency may be taken. Means are provided to impose a DC component of bias voltage across the mixing element at one of three levels. The mixer is such that it has a pair of conduction threshold voltages which are substantially symmetrical above and below zero volts, beyond which the mixing element will be conductive at least when a signal from the local oscillator is imposed on it. The signal from the local oscillator has substantially sinusoidal voltage waveform, with a peak-to-peak voltage which is greater than the voltage difference between the pair of conduction threshold voltages.

Abstract: Technique for reducing local oscillator leakage in integrated frequency conversion circuits is disclosed, which provides coupling an external portion of a resonator circuit to the integrated frequency conversion circuit. The coupling is accomplished without using any of the DC power or ground pins of the conversion circuit. A frequency conversion circuit based on this technique includes resonator, oscillator, and mixer circuits. Part of the oscillator and mixer circuit is encapsulated in a package, whereas at least a portion of the resonator circuit is located outside the package. The outside portion of the resonator circuit connects to at least two external resonator pins of the package such that, during the operating of the conversion circuit, the net current entering the package via said external resonator pins is approximately zero.

Abstract: A system for tracking and correcting drift and dispersion of carrier frequencies in a transmitted signal which includes one or more carrier frequencies and a pilot frequency. The system includes one or more carrier tuners, each for receiving the transmitted signal and for deriving from the received signal and IF carrier signal representing a respective carrier frequency, a mixer for mixing the IF carrier signal and a local oscillator signal to produce a resultant IF information signal, and a demodulator for demodulating the resultant IF information signal to recover the transmitted information.

Abstract: The disclosure relates to the changing of frequencies. The mixing of a signal at a frequency Fe and of the signal of a local oscillator gives a resultant signal that comprises a first component at the useful frequency, a second component at the frequency of the oscillator and a third component which is an image of the first component with respect to the second one. A filtering highly attenuates the third component. A servo-control makes a part of the signal from the oscillator undergo variations in amplitude and phase before adding it to the resultant signal to be filtered; the variations are made so as to obtain a minimum energy from the second component before filtering. Application to the changing of frequencies with suppression of the component at the frequency of the local oscillator.

Abstract: A direct conversion receiver for providing a direct conversion of a radio frequency signal having a carrier frequency comprises a local oscillator for substantially equal frequency to the carrier, and a semiconductor integrated circuit mounting mixers and amplifiers for amplifying inputs to the mixer. The amplifiers amplify the local oscillation signals and/or radio frequency signal inputted from the outside of the semiconductor integrated circuit and supply the amplified signals to the mixers. The mixers mix these inputted signals and output the mixed signals to the outside of the semiconductor integrated circuit. By thus forming the receiver, radiation of the local oscillation signals to outside of the receiver and leakage inside thereof can be suppressed.

Abstract: A microwave mixer is formed of three orthogonally oriented waveguides, each having a rectangular cross-section defined by a pair of opposed broad walls and a pair of opposed sidewalls wherein the ratio of cross-sectional dimensions typically is 2 :1. The mixer includes an input coupling probe, a mixing region, and an output filter disposed serially along a first of the waveguides. A second of the waveguides applies a reference LO signal via the probe to the mixing region, the mixing region including at least one diode with two diodes being employed in the preferred embodiment of the invention. A section of dielectric board serves to support the diodes of the mixing region, components of the filter, and the probe in the first waveguide.

Abstract: An apparatus and method therefor substantially reducing the interference of a harmonic frequency component (301) of a clock signal with a filtered received signal (302), comprises a frequency spreading signal generator (127) and a signal modulator (125). The frequency spreading signal generator (127) produces a frequency spreading signal (130). The signal modulator (125) modulates the clock signal, produced by a clock signal generator (129), with the frequency spreading signal (130) to produce a modulated clock signal (131) including a modulated harmonic frequency component (303). The power level of a modulated harmonic frequency component (303), corresponding to the harmonic frequency component interfering with the filtered signal (202-204), is spread over a frequency bandwidth (f.sub.6 -f.sub.7) greater than the predetermined frequency bandwidth (f.sub.4 -f.sub.5) causing the power level of the modulated harmonic frequency component (303) within the predetermined frequency bandwidth (f.sub.4 -f.sub.

Abstract: An electronic apparatus includes at least a receiver having a synthesizer section for selecting a receiving frequency and providing an information signal corresponding to the selected receiving frequency, a microcomputer operating on a clock signal for controlling the synthesizer section, and a circuit responsive to the information signal for shifting the clock frequency when the selected receiving frequency is a frequency disturbed by a higher harmonic of the clock frequency, thereby to avoid disturbance of reception of the broadcast signal without requiring undue reduction of the clock frequency.

Abstract: A receiver apparatus having a mixer circuit, an oscillator circuit and a tuner circuit is provided with a trap circuit, interposed between the tuner circuit and the mixer circuit, for removing disturbing mutual modulation waves generated by receiving two or more RF signals. Further, the mixer circuit employs a double balanced mixer structure to offset two or more disturbing mutual modulation waves.

Abstract: An FM intermediate-frequency circuit into which there is integrated at least a limiter-amplifier (1A) and a phase-locked loop which contains a VCO (4). The limiter-amplifier also includes a level detector. The dynamic range of the level detector is expanded without having to use excessive limiter-amplifier amplification, which would cause oscillation problems, by placing in parallel with the limiter-amplifier (1A) at least a second limiter-amplifier (1B), in connection with which there is also a level detector. The level of the input signal of the second limiter-amplifier (1B) is dropped as compared with that of the first limiter-amplifier (1A) by means of a dividing circuit (R1, R2). The signals (1A, 1B) obtained from the level detectors are combined to form one level detection signal (ITOT). If the signals are in the form of current, the combining can be carried out directly by summing the signals.

Abstract: A system for suppressing spurious product signals and radiation resulting from the leakage of local oscillator signal energy in superheterodyne radio receivers. The system includes a 0.degree. signal splitter, a 180.degree. signal splitter, a pair of mixers and a 180.degree. signal combiner. The splitters split the communications input signal and local oscillator signal into signal components which are mixed together in the mixers to form intermediate frequency components which are combined in the combiner.

Abstract: Phase noise and drift in a broadcast communication system caused by imperfections in transmitter and receiver local oscillators used for up and down conversion of a frequency or phase modulated information signal is eliminated from a downconverted component that is provided for demodulation by adding a pilot frequency component to the modulated signal for mixing by the local oscillator in the transmitter and by frequency locking the local oscillator in the receiver, so that a signal at a frequency equal to the sum of the intermediate frequency and the pilot frequency provided by a phase-locked loop that tracks the pilot frequency component of the downconverted signal is maintained at a desired value. The downconverted signal is mixed with the sum signal provided by the phase-locked loop to provide a component for demodulation at the difference between the pilot frequency and the modulation frequency that is free from the phase noise and drift caused by the local oscillators.

Abstract: Local oscillator feedthrough in a superheterodyne receiver is eliminated by a servo loop-controlled compensation circuit that dynamically tracks the feedthrough signal and adjusts both the phase and amplitude of a compensating signal as needed to maintain the level of the feedthrough signal below a threshold value.

Abstract: A broad-band mixing circuit comprises a transmission line transformer connected between a port adapted to receive a radio frequency signal and a double balanced mixing section, the transformer serving to convert an unbalanced radio frequency signal into a balanced signal, a transmission line transformer connected between a local oscillation signal port and the mixing section, the transformer serving to convert an unbalanced local oscillation signal into a balanced signal, and a transmission line transformer connected between the mixing section and an intermediate frequency signal port, the transformer serving to convert the balanced signal from the mixing section into an unbalanced signal. The noise figure is improved by connecting an electrolytic capacitor in parallel with the balanced output end or the input end of the transmission line transformer for the local oscillation signal.

Abstract: A method and apparatus is disclosed for automatic elimination of frequency instabilities in a receiver frequency converter. Such instabilities result from temperature variations and mechanical vibrations of the local oscillator of a first stage converter. A marker signal is introduced into the first stage down converter mixer and is subjected to the same variations in frequency conversion as is the received signal from an antenna. Intermediate down converted received signals and an intermediate down converted marker signal are received by a second stage converter where such signals are applied to a mixer, the output of which is free of frequency variations introduced by the local oscillator of the first stage converter.

Abstract: A frequency converter for a transmitter of a microwave radio communications system comprises an image reject mixer for mixing an IF signal with an LO or carrier frequency signal to produce an RF signal, and a nulling circuit for providing d.c. offsets to the image reject mixer to reduce carrier leak to the RF signal. The nulling circuit includes a source of phase quadrature chopper signals which are cross modulated with the LO signal to produce a modulated signal, and a single-ended mixer for mixing the modulated signal with part of the RF signal. The output of the single-ended mixer is low pass filtered and the resulting filtered signal is cross demodulated with the chopper signals to produce phase quadrature correction signals, which are integrated to produce the d.c. offsets for the image reject mixer. The arrangement avoids the need for, and expense of, a subsequent carrier frequency filter.

Abstract: An image suppression harmonic frequency converter capable of operating in any microwave range is described. Frequency conversion is obtained by making use of a local frequency which is half that of a conventional converter. In particular, the radiofrequency reception signal is converted into an intermediate frequency signal with suppression of the converted image band. Similarly, the intermediate frequency signal to be transmitted is converted into a single side band radiofrequency transmission signal. The converter comprises two harmonic mixers, a first inquadrature radiofrequency hybrid coupler, a second in-quadrature intermediate frequency hybrid coupler, two appropriate duplexer filters, two low-pass filters, two matching circuits, and two decoupling circuits.

Abstract: Method and apparatus are disclosed for canceling local oscillator feed thru in an IF transmission circuit. The apparatus includes first and second mixers for receiving LO and IF signals. The mixers are operable to upconvert the IF signal while passing an attenuated and phase shifted portion of the LO signal. Bias regulation circuitry is provided for regulating the attenuation and phase shift of the LO signal portion passed by at least one of the mixers such that the LO signal portions are combinable to cancel each other. A coupler circuit is provided for combining the mixer outputs such that the LO signal portions are substantially canceled and an upconverted IF signal remains. The bias regulation circuitry may be self-correcting to optimize cancellation of the LO signal portions.

Abstract: A broad-band mixing circuit comprises a transmission line transformer connected between a port adapted to receive a radio frequency signal and a double balanced mixing section, the transformer serving to convert an unbalanced radio frequency signal into a balanced signal, a transmission line transformer connected between a local oscillation signal port and the mixing section, the transformer serving to convert an unbalanced local oscillation signal into a balanced signal, and a transmission line transformer connected between the mixing section and an intermediate frequency signal port, the transformer serving to convert the balanced signal from the mixing section into an unblaanced signal. The noise figure is improved by connecting an electrolytic capacitor in parallel with the balanced output end or the input end of the transmission line transformer for the local oscillation signal.

Abstract: A heterodyne stage of a receiver which includes a conventional mixer circuit and local oscillator circuit further includes a differential amplifier circuit which measures the amplitude of the injection signal generated by the local oscillator circuit and controls it precisely to a desired reference level by adjusting the current bias supply to the local oscillator circuit within a banded range to ensure start-up of the local oscillator upon energization and to protect against loss of injection signal under all operating conditions. The differential amplifier circuit provides for a precise amplitude reference setting and sufficient closed-loop gain for controlling the amplitude of the injection signal with a minimum of error between the measured and reference values.

Abstract: A simplified carrier phase control apparatus used in a modem for demodulating a quadrature amplitude modulated data signal, to correct phase jitters of a carrier signal due to a 50 Hz or a 60 Hz frequency of the commercial power supply, and its harmonic wave frequency components. The carrier phase control apparatus has a predictive filter for predicting a carrier phase jitter, the predictive filter composed of band-pass filters with center frequencies of 50 Hz and 60 Hz, and a circuit where the output signals of the band-pass filters are multiplied by the coefficients and added linearly.

Abstract: The tuner section of a communications receiver 10 includes a gallium arsenide voltage controlled oscillator 48 for upconverting the received signal in mixer 18. Phase noise and post tuning drift associated with oscillator 48 is impressed onto the signal supplied by a second oscillator network 46. Thus, the outputs of mixers 18 and 78 both contain noise and post tuning drift associated with the gallium arsenide oscillator 48. Mixer 28 is used to substract the noise and drift component on line 30 from that on line 32 to thereby provide an output 14 which is substantially free of the noise and drift associated with the efficient, but noisy gallium arsenide VCO 48.

Abstract: The operating frequency of a radio transceiver and at least one further variable operating parameter of the radio transceiver are controlled in accordance with pre-stored information. Transmit operating radio frequency information is stored in a memory together with associated optimum modulation deviation level information (e.g., so as to maintain a predetermined modulation level at each operating frequency). Receive operating radio frequency information is similarly stored in the memory along with information indicating whether microprocessor clock oscillator frequency is to be shifted (e.g., so as to avoid spurious interfering harmonics emanating from the clock). When operating in the transmit mode, pre-stored modulation gain level information associated with the selected transmit frequency controls the gain of the modulator circuits to compensate for expected changes in modulator circuit gain with change in transmit radio frequency.

Abstract: A paging receiver and a method for minimizing spurious interference signals in the radio frequency (RF) stages and the intermediate frequency (IF) stages. The paging receiver includes a receiving means, a timing means, a voltage converting means, and a decoding means. A frequency for the timing signals generated by the timing means is selected to minimize spurious signal response. The timing signals are simultaneously applied to the decoding means and the voltage converting means. The frequency of the timing signal can be varied to minimize spurious signal response. The decoding means is notified of the timing signal frequency to effect the detecting and decoding of received coded information in real time.

Abstract: A frequency dividing arrangement 5 comprises a frequency divider 6 coupled to an active filler 7 which is operative to suppress output radiation from the frequency dividing arrangement. The arrangement 5 may be incorporated into a frequency synthesis loop 4 of a television tuner circuit in order to reduce interference between the loop 4 and a down conversion stage of the tuner circuit.

Abstract: A tuner circuit for converting the frequency of an input signal with a local oscillator to a predetermined channel frequency. The tuner circuit includes an attenuation circuit responsive to the input signal for controlling the attenuated level of the input signal for reducing cross modulation and intermodulation distortions of the circuit, and for reducing distortion from the interference of the local oscillation, an amplifier circuit coupled to the attenuation circuit for amplifying the attenuated input signal, and a frequency conversion circuit coupled to the amplifier circuit for converting the frequency of the amplified input signal to a corresponding predetermined channel frequency.