Alps Electric Co., Ltd.

Shigeru Osada

Takeo Suzuki

Toshiro Furuta

Masaki Yamamoto

Akira Takayama

Yasuharu Kudo

Masashi Suzuki

Yoshihiro Sato

Takao Suzuki

A tuning circuit comprises, at least, a first circuit Kwhich serially connects a first variable capacitor elementand a second variable capacitor element, an inductance elementwhich is parallely connected to the first circuit Kand constitutes a resonance circuit with the first circuit K; a second circuit Kwhich includes a switch elementand a third resistorserially connected to each other and is parallely connected to the first circuit K; and a first resistorand a second resistor andwhich are connected to both ends of the first variable capacitor element, respectively and apply a predetermined tuning voltage.

Tuning circuit preventing a deterioration of Q value

A signal adder circuit includes: an adding unit that includes at least a pair of amplification elements in which a constant current flows between ground terminals and a ground, input signals having different phases are input to input terminals, and output terminals to which a power supply voltage is applied are connected to each other; a gain control unit that is provided between the ground and each of the ground terminals of the amplification elements so as to adjust the amplitudes of the input signals having different phases; and a phase control unit that is provided between the ground and each of the ground terminals of the amplification elements so as to adjust the phases of the input signals having different phases.

Signal adder circuit capable of removing effects due to phase error or amplitude error of I and Q signals

A direct conversion circuit includes first and second mixers to which a radio frequency signal is input. An oscillator supplies the first and second mixers with local oscillation signals whose phases are orthogonal to each other. A baseband processing circuit processes baseband signals output from the first and second mixers. A level-difference correcting circuit which corrects the two baseband signals input to the baseband processing circuit so that the levels of both are equal to each other is provided in a stage before the first and second mixers. The levels of the baseband signals are corrected by changing relative levels of the radio frequency signal input to the first mixer and the radio frequency signal input to the second mixer.

Direct conversion circuit having reduced bit errors

In a coupling adjusting structure for a double-tuned circuit according to the present invention, first and second coils are configured such that a pair of first conductive patterns formed on a first surface of a printed circuit and a corresponding pair of second conductive patterns formed on a second surface of the printed circuit board are connected via corresponding connecting conductors, thereby making the first and second coils low and thin. Also, one end of the first coil and the corresponding end of the second coil are disposed close to each other, a first ground conductive pattern is disposed at least on the first surface of the printed circuit, and a first jumper connected to the first ground conductive pattern is disposed between the first and second coils so as to adjust an inductive coupling of the double-tuned circuit, thereby achieving a coupling adjusting structure for a double-tuned circuit whose inductive coupling is adjustable.

Coupling adjusting structure for double-tuned circuit

A TV signal receiving tuner which is small in size and inexpensive due to a reduced number of local oscillators. In the TV signal receiving tuner, a local oscillation signal output from a local oscillator is directly applied to a first mixer through a first programmable divider to receive a UHF TV signal, the local oscillation signal output from the local oscillator is applied to the first mixer after its frequency is divided to 1/3 by the first programmable divider to receive a VHF high-band TV signal, and the local oscillation signal output from the local oscillator is applied to the first mixer after its frequency is divided to 1/5 by the first programmable divider to receive a VHF low-band TV signal.

TV signal receiving tuner capable of outputting oscillation signal having wide frequency band by means of single local oscillator

Needless signal that causes interference is prevented from entering to eliminate the generation of interfering signal. A television tuner is provided with a band switching circuit to which television signals of a plurality of channels arranged in a predetermined frequency band are supplied, the band switching circuit has a plurality of filters having the cutoff frequency of every one octave frequency in the predetermined frequency band, the cutoff frequency of the plurality of filters is made continuous every one octave in the predetermined frequency band, and the television signal of the channel to be received is sent out through a specified filter having the cutoff frequency within one octave from the frequency of the television signal of the channel to be received.

Television tuner that generates no interfering signal

A coupling adjusting structure for a double-tuned circuit contains first and second coils that are configured such that a pair of first conductive patterns formed on a first surface of a printed circuit and a corresponding pair of second conductive patterns formed on a second surface of the printed circuit board are connected via corresponding connecting conductors. One end of the first coil and the corresponding end of the second coil are disposed close to each other. A first ground conductive pattern is disposed at least on the first surface of the printed circuit. A first jumper connected to the first ground conductive pattern is disposed between the first and second coils to adjust an inductive coupling of the double-tuned circuit.

A television tuner includes a mixer circuit for receiving a television signal or an FM signal, and a local oscillator circuit for generating an oscillation signal received by the mixer circuit. When the television signal is received, a television intermediate-frequency signal is generated by the mixer circuit. When the FM broadcast signal is received, an FM intermediate-frequency signal having a frequency converted to about 10.7 MHz is generated by the mixer circuit.

Television tuner having simple layout and capable of receiving FM broadcast signals without interference

In the surface mount typed electronic circuit of the invention, an insulating substrate has an inductance element formed in a conductive pattern whose end portions are connected to the second lands. A bare chip is superimposed on the insulating substrate, so as to respectively connect the first electrodes and the second electrodes to the first lands and the second lands. Therefore, since the inductance element is positioned below the bare chip, the length of the connecting conductor between the inductance element and the semiconductor circuit can be extremely shortened, and a high-Q electronic circuit, especially in high-frequency, can be provided.

Surface mount typed electronic circuit of small size capable of obtaining a high-Q

A switch circuit is provided for at least one of a previous stage of a VHF-band frequency converter and a previous stage of a UHF-band frequency converter. Each switch circuit passes a signal when a frequency converter at a subsequent stage of the switch circuit is operating, and does not pass a signal when the frequency converter at the subsequent stage of the switch circuit is not operating.

TV-signal receiving tuner with reduced extraneous emission

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 demodulator is able to demodulate a television signal and an FM broadcast signal by a common demodulator. Also, a receiver is able to output television video signal and audio signal and an audio signal of the FM broadcast signal by the common demodulator without using a second mixer for frequency-converting the FM broadcast signal to provide an audio intermediate frequency signal of 10.7 MHz when the FM broadcast signal is received. A demodulator includes a first input terminal, a second input terminal, a third input terminal and a change-over switch and wherein the change-over switch connects the first input terminal, a video detector and a video carrier generator to receive the television signal and the change-over switch connects the third input terminal, the video detector and the video carrier generator to receive the FM broadcast signal.

Television signal and FM broadcast signal demodulator and television signal and FM broadcast signal receiver

A television signal receiving tuner comprising: an input terminal for admitting VHF and UHF band television signals; a correcting circuit connected to the input terminal and having inductors to correct an effective length of an antenna; a branching filter for branching the signals from the correcting circuit into VHF band television signals and UHF band television signals to be output separately; a VHF tuner unit for receiving the VHF television signals from the branching filter; and a UHF tuner unit for receiving the UHF television signals from the branching filter; wherein values of the inductors are made variable

Television tuner capable of receiving signals without being restricted by application site and television signal receiving unit for personal computer using the same

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Fukushima-ken, Japan

Shigeru Osada