Abstract: Aspects of this disclosure relate to a tunable filter with harmonic rejection. The tunable filter includes mutually coupled inductors and a tunable capacitance circuit electrically connected to at least one of the mutually coupled inductors. The tunable capacitance circuit includes N switches configured to adjust effective capacitance of the tunable capacitance circuit to tune harmonic rejection of the tunable filter for at least 2×2N harmonics. The tunable filter can filter a radio frequency signal. Related methods, radio frequency systems, radio frequency modules, and wireless communication devices are also disclosed.

Abstract: A time-interleaved circuit includes an input buffer, a plurality of track-and-hold circuits, and a plurality of isolation inductors. The input buffer is configured to receive an input signal having an input voltage and to output an output signal having an output voltage. The track-and-hold circuits are electrically coupled in parallel with each other. Each track-and-hold circuit is electrically coupled in series with the input buffer. Each isolation inductor is electrically coupled to the output of the input buffer and at least one of the track-and-hold circuits.

Abstract: Apparatus and methods are provided for coupling RF signals. A lattice coupler design incorporating a pair of shunt inductors provides (i) a virtual ground for biasing and (ii) improved performance characteristics, in both splitter and combiner configurations. Magnetic coupling between the shunt inductors can be selected to maintain improved performance characteristics over a wide bandwidth, while retaining compactness and high efficiency. A design procedure, variations, and results are disclosed.

Abstract: Disclosed herein is a symmetric split planar transformer in the context of a DC-DC isolated converter. The symmetric split planar transformer reduces or eliminates asymmetry in the distribution of parasitic capacitance across the isolation barrier going from one end to another end of a primary coil, and as a result, undesirable electromagnetic interference (EMI) due to common mode dipole emission across the isolation barrier may be reduced. In some embodiments, the primary winding is split into at least a first coil and a second coil, each occupying a different area side-by-side on a substrate. The transformer is symmetric in the sense that a capacitive coupling of the first coil to a secondary winding is the same as a capacitive coupling of the second coil to the secondary winding, such that common mode EMI may be reduced. Each coil may include stacked spiral coil portions in multiple metal planes to increase inductive density across the isolation barrier.

Abstract: Exemplary embodiments are disclosed of signal level indicators and antenna assemblies including the same. In an exemplary embodiment, an antenna assembly includes an antenna configured to be operable for receiving signals, a signal level indicator for indicating a strength of signals received by the antenna, and an amplifier coupled for communication with the antenna, the signal level indicator, and a signal output. The amplifier is configured to be operable for amplifying signals received by the antenna.

Abstract: A time-interleaved circuit includes an input buffer, a plurality of track-and-hold circuits, and a plurality of isolation inductors. The input buffer is configured to receive an input signal having an input voltage and to output an output signal having an output voltage. The track-and-hold circuits are electrically coupled in parallel with each other. Each track-and-hold circuit is electrically coupled in series with the input buffer. Each isolation inductor is electrically coupled to the output of the input buffer and at least one of the track-and-hold circuits.

Abstract: An electronic control unit (ECU) for vehicles is described, including memory to store encrypted data and unencrypted data; a main control unit operatively connected to memory to access unencrypted data; and a hardware encryption-decryption device operatively connected to memory to access encrypted/decrypted data for decryption using a hardware algorithm and for encryption using a hardware algorithm. Data in the memory is decrypted by the hardware encryption-decryption device using the hardware algorithm and stored in memory for use by the main control unit. Data in memory is encrypted by the hardware encryption-decryption device using the hardware algorithm for storage in memory. The main control unit and the hardware encryption-decryption device are separate integrate circuits on a same substrate or SOC and are connected by a bus and can process data in parallel. An external bus can communicate encrypted information with the ECU to allow encrypt/decrypt at run time (on-the-fly) and wire-speed.

Abstract: A semiconductor device includes a filter circuit operable to pass a desired signal component of a high-frequency signal inputted and operable to attenuate a harmonic component of an integral multiple of the desired signal, wherein the filter circuit includes a first inductor and a second inductor coupled in series to a signal line transmitting the high-frequency signal, a first variable capacitor coupled between a power supply line and a node of the first inductor and the second inductor, and a second variable capacitor coupled between the signal line and the power supply line.

Abstract: A receiver includes a mixer configured to convert a radio frequency (RF) signal into a baseband, an impedance shaping unit configured to shape a magnitude of load impedance seen in an output terminal of the mixer in a frequency band of an interference signal converted into the baseband so as to reduce the magnitude of the load impedance, and a trans-impedance amplifier configured to amplify the signal converted into the baseband.

Abstract: Embodiments of apparatuses, systems and methods relating to temperature compensation of acoustic resonators in the electrical domain are disclosed. Other embodiments may be described and claimed.

Abstract: A method of providing frequency dependent signal attenuation. An RF input signal is split into a first signal portion and a second signal portion. Discrete time filtering, a negative group delay and bandstop filtering are applied to the first signal portion to provide a filtered signal portion. The second signal portion is applied to a component, and a component output signal portion is received from the component. The component output signal portion is combined with the filtered signal portion to provide an RF output signal having frequency dependent attenuation.

Abstract: To implement a filter circuit with low noise and a low cutoff frequency in a smaller area, a filter circuit has a first circuit which receives an input signal supplied to an input terminal, amplifies the signal, and outputs the amplified signal to an output terminal, a first differential amplification circuit for receiving the output signal of the first circuit through a first capacitance element, a first resistance element for forming a negative feedback path between the input and output of the first differential amplification circuit, and a second resistance element for forming a negative feedback path between the output of the first differential amplification circuit and the input of the first circuit.

Abstract: An antenna with a built-in filter for use in an electronic device includes: an antenna element; and a circuit board unit connected to the antenna element, wherein the circuit board unit includes: a filter circuit that filters input and output signals of the antenna element; and a matching circuit that performs impedance matching of the antenna element.

Abstract: A filter package for communications equipment includes two or more filters in die form, each having a different frequency response. A first switch and a second switch are operatively connected to the filters and are configured to select a desired filter for operation in a signal stage of the equipment. The filters are aligned and stacked one over the other in the form of a package having an input terminal that is tied to a common terminal of the first switch, and an output terminal tied to a common terminal of the second switch. When the input and the output terminals of the filter package are connected to corresponding terminals of an intermediate frequency (IF) stage in a communications transceiver, the package can support both narrowband and wideband waveforms defined by the Joint Tactical Radio System (JTRS).

Abstract: The present invention is a hybrid RF-digital signal processor-based filter for multiband radio architectures, systems capable of spectrum re-farming and software defined radios It performs low-loss frequency agile multiple notch filtering at RF where a large dynamic range exists at a filter input between signals in a stopband and passband It is a frequency dependent signal attenuation apparatus having two paths connected together by directional couplers The first path comprising a component such as a delay component or duplexer The second path comprising, in series, a down converter, a digital filter, an up converter, and a bandstop filter At the output of a power amplifier, the invention can be used to attenuate spurs, or noise within bands with strict emission constraints At the input of a low noise amplifier, the invention can be used to attenuate blockers and transmitter noise outside of the receiver passband.

Abstract: Techniques for a receiver includes a low noise amplifier, a Q-enhanced bandpass filter on a chip, and an analog to digital converter (ADC) at a sub-sampling speed suitable for an intermediate frequency (IF) signal. In some embodiments, a temperature compensation circuit is included. The receiver has an effective noise level less than 7 dB. In some embodiments a 1-bit ADC is used. In some of these embodiments, one or more switches in the ADC are inverted to cancel charge injection.

Abstract: An integrated circuit (IC) includes multiple circuits isolated with respect to one another. Each circuit of the multiple circuits includes an inductor pair formed in a loop pattern on a same layer as at least one other inductor pair from another circuit of the multiple circuits, such that the inductor pair surrounds and is isolated from the at least one other inductor pair.

Abstract: The present invention is a hybrid RF-digital signal processor-based filter for multiband radio architectures systems capable of spectrum re-farming and software defined radios. It performs low-loss frequency agile multiple notch filtering at RF where a large dynamic range exists at a filter input between signals in a stopband and passband. It is a frequency dependent signal attenuation apparatus having two paths connected together by directional couplers. The first path comprising a component such as a delay component or duplexer. The second path comprising a bandstop filter connected to a down converter, a digital filter, and an up converter. At the output of a power amplifier, the invention can be used to attenuate spurs, or noise within bands with strict emission constraints. At the input of a low noise amplifier, the invention can be used to attenuate blockers and transmitter noise outside of the receiver passband.

Abstract: A tuner uses a bank of tracking filters to preselect a channel to be received. Each tracking filter covers a range of frequencies. The tracking filters are tunable in frequency using switched capacitors and are tunable in gain by using switched resistors. The switched resistors can be controlled by an automatic gain control circuit that monitors the selected signal and adjust the tracking filter gain to achieve a desired signal level. A switch directs the received signal or signal from a test tone generator into the tracking filters. The test tone, generated by a frequency agile circuit, can be used to calibrate the filters, both in frequency and gain.

Abstract: There is provided with a filter circuit, including: an input terminal configured to input signals; a band stop filter configured to have a center frequency of input signals from the input terminal in a stop band and configured to reflect signals in the stop band that is included in the input signals and pass signals outside the stop band; a band pass filter configured to have a pass band including the stop band, and configured to pass signals in the pass band out of the signals having passed through the band stop filter; a synthesis circuit configured to synthesize the signals reflected on the band stop filter and the signals having passed through the band pass filter to obtain synthesis signals; and an output terminal configured to output the synthesis signals.

Abstract: A radio frequency (RF) phase shifter having an RC-CR circuit that includes a first capacitor having a first capacitor node and a second capacitor node and a first resistor coupled between the first capacitor node and a ground. The RC-CR circuit also includes a second resistor having a first resistor node and a second resistor node and a second capacitor coupled between the first resistor node and the ground. The RF phase shifter generates arbitrary phase shift by using a scheme of adding two perpendicular vectors with variable gains (or amplitudes).

Abstract: In a SAW-less receiver involving a passive mixer, novel degenerative impedance elements having substantial impedances are disposed in incoming signal paths between the differential signal output leads of a low-noise amplifier (LNA) and the differential signal input leads of the passive mixer. The passive mixer outputs signals to a transimpedance amplifier and baseband filter (TIA). Providing the novel degenerative impedance elements decreases noise in the overall receiver as output from the TIA, with only minimal degradation of other receiver performance characteristics. In some examples, the passive mixer receives local oscillator signals having duty cycles of substantially less than fifty percent. In some examples, the degenerative impedance elements can have one of several impedances.

Abstract: A multi-band low noise amplifier (LNA) includes multiple low noise amplifying circuits configured to selectively operate in corresponding frequency bands. The low noise amplifying circuits include corresponding amplifying units and degenerating units. The degenerating units include first inductors, which are arranged in loop patterns isolated from each other on a same layer, such that one first inductor surrounds at least one other first inductor. A current flows through a selected first inductor included in a selected low noise amplifying circuit of the low noise amplifying circuits.

Abstract: A circuit package providing voltage isolation includes at least one output and first circuitry located in a substrate of the circuit package for performing an operation. A transformer located in the metal layers of the circuit package provides voltage isolation between the first circuitry and the at least one output.

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

Abstract: A system and method integrates signal filters in a multiband transceiver. A preferred embodiment comprises an amplifier with a first tunable capacitor coupled to a signal input and a tunable filter. The tunable filter comprises an input stage with a first pair of inductors arranged in a dipole configuration and a second tunable capacitor coupled in parallel to the first pair of inductors and an output stage inductively coupled to the input stage, the output stage includes a second pair of inductors also arranged in a dipole configuration and a third tunable capacitor coupled in parallel to the second pair of inductors. The inductors are realized using bond wire or any other high Q material. The first tunable capacitor, the second tunable capacitor, and the third tunable capacitor can be tuned using a master-slave tuning configuration to adjust the operating frequency of the amplifier and the tunable filter to enable frequency band compatibility with multiple communications protocols.

Abstract: An active step attenuator can attenuate the RF signal from a cable modem or other RF source. The active step attenuator converts the RF energy into a DC control signal that controls the attenuation applied to the RF signal. The voltage of the control signal is proportional to the RF energy, so that the active step attenuator attenuates a stronger RF signal more than a weaker RF signal. The active step attenuator may be in the form of a diplex circuit, one branch of which passes signals in one frequency band without attenuation and the other branch of which actively attenuates signals in another frequency band.

Abstract: A receiver for receiving a radio frequency signal includes an attenuator for attenuating a disturbance signal such as an image signal which causes disturbance to a received frequency of the radio frequency signal, on the basis of set information of the received frequency. The attenuator includes a trap circuit for producing a resonance frequency in accordance with the set information. The trap circuit is connected on a supply line for the radio frequency signal and suppresses the disturbance signal by the resonance frequency.

Abstract: A surface acoustic wave filter element has a piezoelectric substrate; and a plurality of inter-digital transducer (IDT) electrodes formed on the piezoelectric substrate, wherein at least one of the plurality of IDT electrodes is connected to a balanced type terminal and other IDT electrodes are connected to balanced type terminals or unbalanced type terminals, and first wiring electrode means which is connected or to be connected to the at least one IDT electrode and second wiring electrode means which is connected or to be connected to the other IDT electrodes are disposed on planes different from each other.

Abstract: An RF receiver (12) includes a channel estimator (52). The channel estimator (52) includes a channel estimation filter (82), error signal generator (84), and normalized Least-Mean-Square (NLMS) filter-definition generator 86. The filter (82), error generator (84) and NLMS filter-definition generator (86) function together as an adaptive estimator. An error signal (90) is formed with a received signal (48). The filter (82) filters an estimated transmit signal (74) constructed from lower confidence decision data (66) and higher confidence known preamble data (30?). An adaptive filter definition (94) is formed in a feedback, loop which minimizes correlation between the estimated transmit signal (74) and the error signal (90). A convergence signal (122) is modulated in synchronism with the changes between lower and higher confidence data in the estimated transmit signal (74).

Abstract: The present invention comprises systems and methods for cellular, PCS, GPS and/or Bluetooth mobile communication (e.g., a mobile telephone). The systems and methods employ a fully integrated dual band IFA/loop CDMA antenna for cellular and PCS communication. Fully integrating the CDMA antenna within a PWB provides for mitigation of lumped elements to establish dual banding, and can provide for reduced antenna size, device size, cost and interference form a user's hand. The IFA antenna is configured to transmit and receive within the cellular frequency band via a capacitive tap, and the loop antenna is configured to transmit and receive within the PCS frequency band via an impedance matching stub and ground location. The system and methods further employ a firewall to mitigate antenna coupling, and a metal reflector to reduce the electromagnetic reflection, and improve antenna gain and efficiency.

Abstract: An arrangement for dividing the output signal of the antenna filter of a radio receiver to two different paths, such as two parallel low-noise amplifier branches of a base station. The divider circuit is physically integrated into a resonator-type antenna filter (RXF). This takes place by placing some conductors (332, 333) of the divider inside some conductive part of the filter structure or the resonator cavity and by using the coupling conductor (331) of the output resonator as part of the input line of the divider at the same time. As the divider is used a Wilkinson divider. Due to the arrangement, a transmission line between the antenna filter and the divider becomes unnecessary, and the dielectric losses of the divider are reduced as compared to the prior art, in which case correspondingly inferior noise qualities can be allowed for low-noise amplifiers.

Abstract: A comb-line wireless filter (5) includes an input end (505a), an output end (505b), a first transmission line (501b), a second and third transmission line (501a, 501c) each having a curved shape, and a first, second, and third capacitor (503b, 503a, 503c). The first transmission line has a first transmission line part and a second transmission line part. The second transmission line and the third transmission line are separately on the two sides of the first transmission line part of the first transmission line. The input end and the output end are separately connected to first ends of the second transmission line and the third transmission line. The capacitors are separately connected to first ends of the transmission lines. According to the curved shape of the second transmission line and the third transmission line, the size of the comb-line wireless filter is significantly reduced.

Abstract: A radio frequency management device includes a microprocessor, output devices connected in parallel to the microprocessor, reading units respectively connected to the output devices, each reading unit comprising an antenna coil, a blocking coil, a radio frequency driver module for driving the antenna coil, and a blocking driver module for driving said blocking coil to shield the antenna coil from the radio frequency driver module, and a reading and writing device connected to the microprocessor. The microprocessor controls the output devices in such a manner that only one radio frequency driver module is activated to drive the associated antenna coil at any time while the other antenna coils of the other reading units are shielded from the associated radio frequency driver modules by the associated blocking coils; the reading units are processed one after another in a proper order.

Abstract: A method for processing an image using a bilateral filter. The bilateral filter is reformulated at each pixel location in the image into a sum of the original signal value of a central pixel at said pixel location and a bilateral correction term which is a function of local signal differences between the central pixel and its neighbors. The bilateral correction term is calculated using a computationally efficient approximation.

Abstract: A radio frequency (RF) tuner includes a programmable tracking filter bank receiving an RF input and outputting a filtered RF signal. A mixer stage receives the filtered RF signal and outputs a first quadrature component of the filtered RF signal and a second quadrature component of the filtered RF signal. Two variable gain amplifiers receive the first and second quadrature components and output amplitude-controlled I and Q components of the filtered RF signal. In one embodiment, the programmable tracking filter bank includes a plurality of tank circuits each connected to the RF input through an impedance. Each tank circuit include an inductor and a capacitor connected in parallel thereby forming an LC network, and a plurality of switched capacitors in parallel with the LC network and switched in and out of the tank circuit by programmable switches. In another embodiment, the programmable tracking filter bank includes a plurality of peaked low-pass circuits each connected to the RF input through an impedance.

Abstract: A radio frequency (RF) phase shifter having an RC-CR circuit that includes a first capacitor having a first capacitor node and a second capacitor node and a first resistor coupled between the first capacitor node and a ground. The RC-CR circuit also includes a second resistor having a first resistor node and a second resistor node and a second capacitor coupled between the first resistor node and the ground. The RF phase shifter generates arbitrary phase shift by using a scheme of adding two perpendicular vectors with variable gains (or amplitudes).

Abstract: A mixer for tuning to an intermediate frequency signal, an intermediate frequency amplifier provided at a rear stage of the mixer, an intermediate frequency tuning circuit interposed between the mixer and the intermediate frequency amplifier for tuning to the intermediate frequency signal, and a trap circuit interposed between the mixer and the intermediate frequency amplifier for attenuating the signal of an adjacent channel are comprised. By connecting a first switch means to the trap circuit in parallel to turn on the first switch means, the RF characteristic at an input port of the intermediate frequency amplifier or an output port of the mixer can be observed, without being influenced by the trap circuit.

Abstract: A polar modulator contains a phase locked loop which is designed to emit a radio-frequency signal at one frequency to one output, with the frequency being derived from the reference signal and from a phase modulation signal at a control input of the phase locked loop. The modulator additionally has a second signal input for supplying an amplitude modulation signal. The second signal input is connected to a control input of a pulse width modulator, one of whose signal inputs is coupled to the output of the phase locked loop. The pulse width modulator is designed to vary the duty ratio of a signal which is applied to the signal input, with this variation being adjustable via a regulation signal at the control input. A filter can be connected downstream from the output of the pulse width modulator and suppresses higher harmonic components in a signal which can be tapped off at the output of the pulse width modulator.

Abstract: The invention relates to a television signal receiver comprising a radio-frequency tuner (1) and at least one subsequent surface-acoustic wave filter (2), in which the radio-frequency tuner (1) filters a RF television signal applied to its input and converts it to an intermediate-frequency television signal which is coupled to the surface-acoustic wave filter (2). The RF tuner (1) has at least one output stage (16) which supplies the IF television signal converted to the intermediate frequency. The output stage (16) is directly connected to an output (6) of the RF tuner (1), while a switch (10) is associated with it, by means of which switch the IF television signal is supplied to a second output (8). A further switch (11) is associated with the second output (8), by means of which switch the associated output (8) is switchable to a fixed reference potential.

Abstract: A band edge amplitude reduction system changes the filtering characteristics of a receiver based on the amplitude of signal(s) adjacent to an edge of the operating band of the receiver and/or of signals not under the power control of the receiver. For example, the receiver measures the power level over a bandwidth at the band edges of the operating band of the receiver. If the signals adjacent to the operating band are strong enough relative to the signal power within the operating band, overload protection circuitry changes the filtering characteristics of the receiver to improve the attenuation of the signal(s) from the adjacent band(s). In certain embodiments, the overload protection circuitry switches in filter(s) with a narrower bandwidth to attenuate the signal(s) from adjacent band(s) at the edge(s) of the operating band of the receiver, thereby preventing interference with or the overload of the receiver by signals from outside the operating band and/or not under the power control of the receiver.

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

Abstract: Remotely controllable actuators are provided to alter the cavity size of bandpass cavity filters to alter the bandpass characteristics. In one embodiment, a stepper motor is used to provide lateral movement of a tuning plate to alter the size of the cavity. The neck of the cavity is also changed in length through the use of a tuning motor. A feedback loop is used to provide fine tuning of the length of the neck in response to changes due to temperature and vibration to offer maximum propagation of the signal to be transmitted. A coupling tuner is used to adjust to the resulting change in Q to the cavity. A tuning processor is used to receive signals from a remote location identifying the desired characteristics of the filter.

Abstract: In a single-to-differential conversion circuit for converting a single signal into a differential signal formed of first and second signal components: a source-grounded (or emitter-grounded) first transistor receives the single signal at the drain (or collector); the gate (or base) and drain (or collector) of the first transistor are connected; the gate (or base) of a source-grounded (or emitter-grounded) second transistor is connected to the gate (or base) of the first transistor; the drain (or collector) of a gate-grounded (or base-grounded) third transistor outputs the first signal component; the source (or emitter) of the third transistor is connected to the drain (or collector) of the first transistor; the drain (or collector) of a gate-grounded (or base-grounded) fourth transistor outputs the second signal component; and the source (or emitter) of the fourth transistor is connected to the drain (or collector) of the second transistor.

Abstract: A SAW device includes two surface-acoustic-wave filter elements arranged so as to have a balanced-to-unbalanced conversion function. The surface-acoustic-wave filter elements include two first reflectors and two second reflectors. In each surface-acoustic-wave filter element, three IDTs are arranged on a piezoelectric substrate in a direction in which surface acoustic waves are transmitted so as to be positioned between one first reflector and one second reflector. The first reflectors differ in structure from the second reflectors.

Abstract: A mobile station is constructed to include a transceiver comprising a transmitter circuit having a transmit RF filter that passes a transmit band of frequencies that is partitioned into transmit frequency channels and a receiver circuit having a receiver RF filter that passes a receive band of frequencies that is partitioned into receiver frequency channels. Also included is an antenna coupled through a duplexer to an output of the transmitter circuit and to an input of the receiver circuit. The mobile station further includes circuitry, responsive to a currently selected RF channel, for compensating for a non-ideal operation of the RF filters and the duplexer over a full bandwidth range of the transmit and receive frequencies. The compensating circuitry compensates for RF filter operation in a transmit RF channel that is nearest to the band of receive RF frequencies and/or compensates for RF filter operation in a receive RF channel that is nearest to the band of transmit RF frequencies.

Abstract: A tuner includes a tunable filter for selecting a desired RF signal in response to a tuning control signal and a tunable image trap for rejecting the undesired image signal corresponding to the desired RF signal responsive to the tuning control signal coupled in cascade between an RF amplifier and a mixer. The tunable trap also serves as an impedance transformation element between the tunable filter and said mixer. The arrangement is particularly useful in a tuner in which the frequency range of the local oscillator signal is below the frequency range of the received RF signals.

Abstract: The method, apparatus, and system for controlling audio anomalies by using a mute switch 51 to prevent output of an auxiliary audio signal 21 in a television signal 20 with an auxiliary audio signal 21, such as a NICAM audio signal or dual language audio signal, adjacent to a first audio signal 22. The mute switch 51 operation is a function of the type of receiver 19 receiving television signal 20 and a function of verifying the presence of an auxiliary audio signal 21 in television signal 20. The present invention controls audio anomalies such as audio whistle and audio pop.

Abstract: A circuit that prevents a receiving signal from leaking to an LNB supply line to thereby deteriorate input VSWR characteristic includes a capacitor of about 1000 pF for removing noise and a capacitor of about 1 pF for passing a high frequency component which leaks to an LNB voltage supply line to the ground provided between the LNB voltage supply line and the ground. By the capacitor of about 1000 pF, a noise component included in the LNB voltage supply line is removed. Further, by the capacitor of about 1 pF, the high frequency signal component which leaks via a choke coil is bypassed to thereby reduce impedance of a node NA over a broad band and prevent a reflecting wave from being produced at the node NA and input VSWR from being deteriorated.

Abstract: A digital television receiver converts very-high-frequency intermediate-frequency digital television signal to a band with uppermost frequency in the lower portion of the high-frequency range. This facilitates RLC analog filtering, such as a Butterworth-Thomson-transition filter or a bridged-T trap filter, being used for suppressing the frequency-modulated audio carrier of co-channel NTSC analog television signal prior to the digital television signal being synchrodyned to baseband for recovering symbol code. The delay distortion introduced by this analog filtering is compensated for in substantial part in surface-acoustic-wave bandpass filtering of the very-high-frequency intermediate-frequency digital television signals. Remnant delay distortion is reduced by channel equalization filtering carried out in the digital regime.