Abstract: A dual-channel passband filtering system having a first, second and third balanced ports for connecting, respectively, to a first transceiver, an antenna and a second transceiver. A first lattice-type passband filter is connected between the first and the second port, and a second lattice-type passband filter is connected between the second and the third port. A phase shifter is used to match the first and second transceiver and the second port. A balun can be used for each port to convert the balanced port to a single-ended port. In each passband filter, two series resonators are use to provide two balanced ends, and two shunt resonators are connected to the series resonators in a crisscross fashion to form a differential or balanced topology. The first and second passband filters have different frequencies.

Abstract: The invention is provided to improve the power efficiency of a power amplifier circuit of a wireless communication system having an output transistor that operates in saturation operation mode and linear operation mode. The invention provides an electronic apparatus (module) used for a wireless communication system in which at least an output power amplifiers and an impedance matching circuit are mounted on one insulating substrate and the impedance of the output terminal of the impedance matching circuit is set to 50&OHgr;, wherein a switching circuit that changes the circuit constant of the impedance matching circuit or the high frequency impedance value in view of the impedance matching circuit side from the output power amplifier depending on the operation condition is provided at the point of the impedance lower than the impedance of the output terminal in the impedance marching circuit.

Abstract: A transceiver has frequency generating means for generating a first signal at a first frequency. The frequency generating means has first tank means for resonating at the first frequency. The transceiver further has frequency multiplication means for multiplying the first signal by an integral multiple of a fundamental frequency of the first signal. The frequency multiplication means has second tank means for resonating at a harmonic frequency of the fundamental frequency, the harmonic frequency being determined by the integral multiple. The frequency multiplication means has output means for outputting a second signal at the harmonic frequency. The first tank means is highly frequency selective around the first frequency, and the second tank means is highly frequency selective around the harmonic frequency. The transceiver has tuning means for simultaneously tuning the first and second tank means, and has up/down-conversion means for up/down-converting the second signal.

Abstract: Transmitter and receiver for wireless communications with improved accuracy and stability in radio frequency control. A transmitter mixes an information-carrying signal (first signal) and a non-modulated wave signal (second signal) with a carrier signal, thereby producing a first and second radio frequency signals for radio wave transmission. A receiver mixes those two radio frequency signals to extract the original information signal. While the received radio frequency signals contain some frequency fluctuations and phase noises that have been introduced at the sending end, such unstable components &Dgr;f will cancel out at the receiving end.

Abstract: The present invention, generally speaking, provides for high-efficiency power control of a high-efficiency (e.g., hard-limiting or switch-mode) power amplifier in such a manner as to achieve a desired modulation. In one embodiment, the spread between a maximum frequency of the desired modulation and the operating frequency of a switch-mode DC-DC converter is reduced by following the switch-mode converter with an active linear regulator. The linear regulator is designed so as to control the operating voltage of the power amplifier with sufficient bandwidth to faithfully reproduce the desired amplitude modulation wave-form. The linear regulator is further designed to reject variations on its input voltage even while the output voltage is changed in response to an applied control signal. This rejection will occur even though the variations on the input voltage are of commensurate or even lower frequency than that of the controlled output variation.

Abstract: The invention relates to an arrangement and method for reducing losses at the transmitting end of a radio apparatus, especially one that operates in more than one system. An interfering transmitter is provided with two antenna filters one of which is a low-pass-type filter and the other a band-pass filter. The filter (BPF) with a higher stop-band attenuation is used only when the receiver (330, LNA) susceptible to interference is in receive state. At other times, the filter (LPF) with a lower stop-band attenuation and, hence, a lower pass-band attenuation, is used as the transmitting-end filter. Advantageously the selection between the different filters is realized using MEMS-type switches (SW31 to SW34). The invention minimizes the mean current consumption of the radio-frequency power amplifier (PA) of the said radio apparatus. The space required by and the production costs of the arrangement according to the invention are relatively small.

Abstract: A radio frequency transmitter having a tunable radio frequency signal generator and an amplifier coupled to the tunable radio frequency signal generator. An aerial is coupled to the amplifier and transmits the amplified radio frequency signal, which may then be received by various radio receivers. The aerial has an output voltage and an impedance. The impedance includes inductive and capacitive reactances. In order to maximize the output voltage of the aerial, an adjustable inductor is coupled to it. The adjustable inductor includes a pair of tuning coils with adjustable ferrite cores. A sampler measures the output voltage of the antenna. The sampled output voltage of the aerial is converted to a digital signal and then compared with a DC reference voltage produced by a processing unit in a comparator. The processing unit is coupled to the comparator and the adjustable inductor and receives the converted signal and analyses its amplitude.

Abstract: A mobile phone apparatus which is capable of meeting the stringent specifications on transmitter noise in the receive band. The mobile phone apparatus has a modulator for producing a signal to be transmitted in a transmit band, a power amplifier for supplying the signal to be transmitted to an aerial, a tunable filter disposed between the modulator and the power amplifier and having a passband and an attenuation band, and a control circuit for tuning the filter such that the passband is at the transmit band and the attenuation band is at a receive band of the apparatus.

Abstract: A transmitter-receiver includes a transmitting circuit for providing an output by converting the frequency of a transmission signal input thereto, a receiving circuit for providing an output by converting the frequency of a received signal input thereto, and a local oscillator which generates an oscillation signal having a local oscillating frequency based on a reference signal. A local oscillator signal splitter is connected to the local oscillator and splits the oscillation signal into substantially similar transmit and receive oscillation signals each at the local oscillating frequency. The local oscillator signal splitter supplies the transmit oscillation signal to the transmitting circuit and supplies the receive oscillation signal to the receiving circuit. The transmitting circuit converts the frequency of the transmission signal in accordance with said transmit oscillation signal, and the receiving circuit converts the frequency of the received signal in accordance with the receive oscillation signal.

Abstract: A portable radio transceiver selectively transmits and/or receives RF signals in two frequency bands and in two modes of operation. The radio transceiver selectively switches between two antennas for operating in either of the two modes, such as a handheld mode of operation using the transceiver's on-board antenna and battery, or a car mode of operation using an external antenna and battery. Either antenna can transmit and/or receive RF signals in the two frequency bands, such as PCS and cellular, for example.

Abstract: A transmitter system having an adjustable monolithic frequency stabilization and tuning internal capacitor circuit. The transmitter system has a transmitter for generating and transmitting a transmitter oscillator frequency signal. A data generating chip is coupled to the transmitter. The data generating chip is used for adjusting and controlling the transmitter oscillator frequency signal. A variable capacitor circuit is located internal to the data generating chip and is coupled to a ground pin and one of a plurality of function pins on the data generating chip. The variable capacitor circuit is used for adjusting and setting the centerpoint of the transmitter oscillator frequency signal.

Abstract: A pair of filter units directs incoming signals from an antenna and outgoing signals to the antenna. One of the filter units blocks the outgoing signals and passes the incoming signals while the other of the filter units blocks the incoming signals and passes the outgoing signals.

Abstract: A summing network for combining and feeding radio frequency signals supplied by radio transmitters to common antenna means, includes conductors, connectors and a stub. In order to make the tuning of the summing network easier, the stub includes a changer for changing the electrical length of the summing network as a response to a control signal fed to the stub.

Abstract: An amplifier circuit (204) having a variable bandwidth comprises an amplifier (300), a capacitive element (304), a first npn transistor (302), and a switch control circuit (306). The first npn transistor (302) has a base coupled to an output terminal (205) of the amplifier (300), a collector coupled to a first reference voltage (113), and an emitter coupled to the capacitive element (304) and the switch control circuit (306). When the first npn transistor (302) is switched off by the switch control circuit (306), a first cutoff frequency is determined by a maximum operating frequency of the amplifier (300). When the first npn transistor (302) is switched on by the switch control circuit (306), a second cutoff frequency is determined by a capacitance of the capacitive element (304). For high frequency operation, the amplifier (300) includes at least a second npn transistor for amplification and the first cutoff frequency is determined by a Miller capacitance of the amplifier circuit (204).

Abstract: A local control mechanism for automatically parking an active combiner filter and activating an alternate combiner filter in an auto-tune combiner in a radio telecommunications network is resident entirely at a remote base station. The mechanism samples the radio frequency (RF) energy level on the active combiner filter in an auto-tune combiner and determines whether the measured RF energy level exceeds a predetermined RF energy threshold. The mechanism then determines the number of RF energy samples taken, compares this number to a trigger number, and parks the active combiner filter and switches to an alternate combiner filter when the number of consecutive RF energy samples below the RF energy threshold exceeds the trigger number.

Abstract: A base-site (304) combines baseband frequency hopping and fast-synthesizer hopping to produce an economical frequency hopping communication system (300). The base-site (304) combines the fast-synthesizer frequency hopping capability of transmitters (307-309) with baseband frequency hopping to produce a frequency hopping communication system (300) which serves the same number of subscribers served by transmitters (208-213) in a purely baseband hopping communication system (200), but with fewer transmitters (307-309). The implementation of frequency-selective cavities (312-317) having very low loss eliminates the need for wideband hybrid combiners (112-114), which in turn eliminates transmitted-signal power loss experienced in a purely fast-synthesizer frequency hopping communication system (100).

Abstract: A coupling network for coupling a signal at a frequency from a voltage source to a load. The voltage source has a source resistance. The load has a load resistance and a load reactance. The ratio of the load reactance to the load resistance greater than 100. The coupling network includes a reactive element and a delay circuit. The reactive element is arranged in series with the load to resonate with the load reactance at the frequency. The delay circuit is between the reactive element and the source, has a delay equivalent to a quarter wave length transmission line at the frequency and has a characteristic impedance equal to the square root of the product of the values of the load resistance and the source required resistance.

Abstract: A communication system includes a filter device for passing only a desired carrier frequency, and a circuit for splitting the passed carrier frequency into a pair of signals. A circuit for feeding back one of the signals to the filter device for causing an oscillation to occur at the desired carrier frequency for direct broadcast purposes.

Abstract: A radio frequency transmitter, amplitude modulated, having a single tuner that tunes the frequency oscillator, the isolating filter and the antenna impedance, all at the same time. The transmitter includes a tunable carrier generator for generating a carrier signal of a desired frequency, and a carrier isolator for filtering the carrier signal so as to ensure a clean, isolated carrier signal. A power amplifier is included for amplifying the signal from the carrier isolator. The power amplifier has a certain output impedance. An antenna is connected for transmitting the amplified signal from the power amplifier. The antenna also has a certain impedance. The transmitter further includes an impedance matching device connected between the antenna and the power amplifier for matching the antenna impedance and the power amplifier impedance. Finally, a single control knob is provided for simultaneously controlling the tunable carrier generator, the carrier isolator and the impedance matching device.

Abstract: A wide band analog frequency divider circuit operable at a high frequency in the GHz band, and a frequency synthesizer utilizing the analog frequency divider circuit. The analog frequency divider circuit comprises an LC series circuit having a capacitor and an inductor connected between the anode and the cathode of a diode, and means for applying a forward bias to the diode. The input signal is supplied from the anode side of the diode, and the output is delivered from the cathode side, or the anode side of the cathode is grounded. The frequency synthesizer is arranged to frequency divide the output of a VCO by the analog frequency divider circuit, and to supply the frequency-divided output to a prescaler. The output of the prescaler is further frequency divided by a programmable divider, and the phase difference between the output of the programmable divider and a reference signal is detected thereby to control the oscillation frequency of the VCO.

Abstract: A FM wireless headphone transmitter which uses a novel technique of varying the transmitted frequency. Instead of the traditional methods of using a variably meshing multi-plate capacitor, the invention uses a printed circuit inductance with a tuning plate attached permanently to the inside of the case so that frequencies are changes by changing cases. An alternative embodiment uses interchangeable tuning plates attached to the inside of the case by hook and loop pile type fastener material. The printed circuit inductance also serves as a transmitting antenna.

Abstract: A high speed antenna coupler and method for rapidly switching binary weighted values of inductance and capacitance into and out of the circuit between an antenna and a utilization circuit without unacceptably degrading the coupler or slowing the switching action. PIN diodes are utilized as switches and the control wires for the PIN diodes are disposed interiorly of the copper tubing which forms the inductance elements. The control wire for a particular inductor is withdrawn from the interior of that inductor adjacent the mid-point thereof so that the control wire will be at the same RF potential as the inductor being controlled. Two diodes are utilized for each inductor, one connected to each end thereof, so that only half of the normal reverse bias is required for switching purposes. Where a transformer is utilized to couple the antenna to the utilization circuit, the control wires may be disposed interiorly of the copper tubing which forms the winding of the transformer.

Abstract: A high power, high frequency radio transmitter is connected to an antenna through an adjustable impedance coupling device which comprises a helical coil having a number of straight-sided triangular turns. Remotely operable, pneumatic cylinders are mounted on each side or segment of the coil turns in electrical contact therewith and have piston rods which can be moved into and out of electrical contact with a respective fixed conductive member or bus disposed alongside the coil. Additionally, a number of capacitors can be connected into the coupler circuit as required by the similar movement of piston rods into contact with a similar bus, each such piston rod being housed within a pneumatic cylinder electrically connected to a respective one of such capacitors.

Abstract: The local oscillator frequency in a communication tuning system is selected to either high side mix or low side mix as appropriate to place the local oscillator frequency and image frequency outside the bandpass range of the bandpass filter. This allows bandpass filters having a frequency range equal to approximately twice the IF frequency in a transmitter, and approximately four times the IF frequency in a receiver.

Abstract: An output circuit for converting a video signal reproduced from a video signal reproducing apparatus such as a video tape recorder, to a signal in the form of an RF signal in terms of a television channel carrier and selectively producing one of two channel carriers, comprises a first filter for eliminating the lower sideband wave of the lower one of the two channels, a second filter connected in series with the first filter for eliminating the lower sideband wave of the higher one of the two channels, and a switch for activating the second filter only when the higher channel is selected to produce the higher channel signal.