Alps Electric Co., Ltd.

Akira Takayama

Michihiro Komatsu

Shigeru Osada

Shigetaka Suzuki

Akio Tadachi

Tsutomu Kunishima

Minobu Okada

Takao Suzuki

Hiroshi Kamada

An amplification circuit includes a semiconductor amplification element, a current feedback circuit that is connected to a terminal close to a ground side of the semiconductor amplification element and can control gain reduction, and a voltage feedback circuit that is connected between an input terminal and an output terminal of the semiconductor amplification element and can control feedback voltage. The feedback voltage of the voltage feedback circuit may be varied according to the gain reduction controlled by the current feedback circuit.

Amplification circuit

A radio frequency amplifier includes a waveguide filter positioned between a first and a second amplifier circuit, which reduces the distortion between the amplifier circuits. The waveguide includes a main body having a cavity.

Radio frequency amplifier with a waveguide filter for isolating amplifying elements

A digital television tuner is realized in which the construction of a baseband signal processing portion is simple, it is difficult for a local oscillation signal to leak to the input end side, and in which image interference is suppressed. The digital television tuner includes a frequency conversion device for converting the frequency of a digital television signal of a channel to be received from among channels arranged in a predetermined frequency band into the highest frequency of the frequency band or higher; two mixing devices for outputting two baseband signals whose phases are mutually orthogonal to each other by demodulating the frequency-converted digital television signal; a local oscillation device for inputting local oscillation signals whose phases are mutually orthogonal to each other to the two mixing devices; and an addition device for adding together the two baseband signals, wherein the frequency of the local oscillation signals is set to be the same frequency as the frequency at the end of the band in the channel of the frequency-converted digital television signal, and one of the baseband signals is converted into the same phase as that of the other, after which the signals are input to the addition device.

Digital blocks television tuner having simple baseband signal processing portion

A disturbance may be prevented from being caused in a satellite broadcasting signal of a reception target by a satellite broadcasting signal in which a frequency is higher by 1 octave. This satellite broadcasting receiving tuner includes first and second tuners to which satellite broadcasting signals of a plurality of channels arranged within a frequency band higher than 1 octave are inputted, a local oscillator which oscillates at the same frequency as the frequency of a desired reception satellite broadcasting signal and a higher harmonic wave attenuating device for passing a fundamental wave of a local oscillation signal from the local oscillator and which attenuated a higher harmonic wave, wherein the local oscillation signal is inputted through the higher harmonic wave attenuating device to the first and second demodulators, a phase of the local oscillation signal inputted to the first demodulator and a phase of the local oscillation signal inputted to the second demodulator are shifted from each other by 90 degrees, and baseband signals are respectively outputted from the first and second demodulators.

Satellite broadcasting receiving tuner which inhibits interference caused by satellite broadcast signals having one octave higher frequency band

A digital television broadcast receiver comprising a digital signal demodulator, wherein the frequency of an intermediate frequency signal is made higher than the maximum frequency of any received signal, the intermediate frequency signal being demodulated by the digital signal demodulator, whereby interference attributable to a carrier signal from an oscillator of the demodulator is suppressed during demodulation.

Digital television broadcast receiver that demodulates an intermediate

A double conversion television tuner capable of receiving analog and digital telecasts and having a reduced number of frequency conversion stages with fewer oscillators to minimize beat disturbances between local oscillation signals, the tuner being made up of fewer circuit components costing less than conventional tuners to manufacture. The inventive tuner comprises a first frequency conversion stage for converting in frequency a channel-select received signal to a first intermediate frequency signal to be output, a second frequency conversion stage for converting in frequency the first intermediate frequency signal to a second intermediate frequency signal to be output, and an analog and a digital demodulator for demodulating the second intermediate frequency signal. The local oscillation signal of the second frequency conversion stage is switched to a first frequency if the base-band signal of the channel-select received signal is an analog signal, and to a second frequency if the base-band signal is a digital signal, the second frequency being higher than the first frequency.

Double conversion television tuner

The invention provides a filter circuit for use in a double-conversion TV tuner exhibiting low diode insertion loss, in which intermodulation distortion does not occur even when an incoming signal has a large amplitude. In the filter circuit according to one preferred embodiment of the invention, there are provided three bandpass filters (BPFs) which allow corresponding RF signals in different frequency bands to pass through them, and six variable attenuation diodes whose impedance is controlled by an AGC voltage applied to an AGC terminal (16). There are also provided switching diodes (20) disposed between an input terminal (1) and the inputs of three BPFs so that the switching diodes (20) select exclusively one of three BPFs so as to apply an RF signal received at the input terminal (1) only to the selected BPF (it will be assumed hereinbelow that the BPF (21) is selected). In this arrangement, not only the impedance of variable attenuation diodes (22, 23) in the selected BPF (21) which provides the extracted RF signal, but the impedance associated with all variable attenuation diodes is controlled by the AGC voltage.

Reception band switching circuit with variable attenuation control

A microwave oscillator of the type in which a dielectric resonator is disposed inside a conductive housing, characterized in that a conductive rod-like member is disposed inside the housing and arranged in parallel with the axis of the dielectric resonator with one end connected electrically to the housing and the other end left free. Preferrably, the rod-like member is made so thin as to interrupt little the magnetic flux generated by the dielectric resonator, and the resonance frequency of the housing is selected lower than that of the dielectric resonator.

Microwave oscillator

A band pass filter and frequency converter in a frequency conversion circuit are arranged such that a strip line constituting a part of the frequency converter and having a 1/4 wavelength relative to that of a local oscillation signal, is disposed adjacently in parallel to one of the opposite sides of a U-shaped line of the band pass filter to thereby form inductive coupling through which the frequency converter and the band pass filter are connected to each other at a high impedance open end of the above-mentioned strip line, so that the inductive coupling is made to be sufficiently strong. Accordingly, it is possible to produce a sufficiently large intermediate-frequency signal.

Frequency conversion circuit

An oscillator with a dielectric resonator capable of providing a designated output and being suited for mass production comprising an insulating substrate, a strip structure, a dielectric resonator located adjacent to the strip structure, the last two being mounted on the substrate, and an oscillatory transistor connected to one end of the strip structure. The strip structure consists of two spaced strip sections interconnected by an electrically-conductive bridge-shaped connector section having a conductor part, which is located further away from the insulating substrate and closer to the dielectric resonator than the two strip sections.

Oscillator having improved coupling between stripline and dielectric

In a microwave oscillator having a metal frame which defines a cavity portion, a dielectric resonator which is received in the cavity portion, a trimmer plate which opposes to the dielectric resonator in the cavity portion, a flat plate which closes one open end face of the cavity portion and to which the trimmer plate is movably attached; the improvement wherein the cavity portion has a second open end face, and this open end face is closed by a second flat plate to which the dielectric resonator is fastened. The dielectric resonator is readily assembled, and the parallelism between the dielectric resonator and the trimmer plate is readily established.

A microwave receiver is constituted by an antenna having a reflector and a primary radiator, and a converter having an unbalanced input terminal. A core conductor projected from the unbalanced terminal of the converter is extended inside the reflector through a bore formed therein so as to function as the primary radiator of the antenna. The converter is fixed directly to the wall of the reflector.

Growing community of inventors

Fukushima-ken, Japan

Akira Takayama