Alps Electric Co., Ltd.

Takeo Suzuki

Shigeru Osada

Masaki Yamamoto

Ikutaro Inoue

Yasuharu Kudo

Masatsugu Aoki

Hideo Tamai

Masashi Suzuki

Shigeo Ohta

Kazumi Kuwabara

Yukio Ohtaki

Toshiro Furuta

Akihisa Iikura

Akira Asao

Kouta Iijima

Shoichi Asano

Kimihiro Nakao

Takeshi Shimizu

Osamu Tatsumi

Provided is an AGC circuit which is hard to be influenced by the level of an input signal. The AGC circuit includes an amplification elementwhich has an input terminalfor receiving an input signal Vin, a ground terminalconnected to ground through at least a first resistor RA, and an output terminalwhich is connected to a power supply source Vcc through at least a second resistor RB and amplifies and outputs the input signal Vin; an AGC voltage generating partwhich is provided at the subsequent stage of the amplification elementand outputs an AGC voltage according to the strength of the input signal as an analog signal; a signal converting partwhich digital-converts the AGC voltage into a AGC control signal Ato Bhaving a predetermined number of bits; a current negative feedback circuitwhich changes the impedance ZA of the ground terminal including the first resistor RA to adjust an gain; and a voltage dividing circuitwhich changes the impedance ZB of the output terminal including the second resistor RB to adjust the gain.

AGC circuit which is hard to be influenced by level of input signal

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

An OFDM receiver has four antennas or more for receiving an OFDM modulated high frequency signal, and plural OFDM demodulators for inputting a baseband signal of a time domain thereto on the basis of the high frequency signal and outputting the baseband signal of a frequency domain, wherein the OFDM demodulators are arranged every plural antenna groups with two or more of the antennas as one group, and a signal is diversity-synthesized by a first phase shifter until the baseband signal of the time domain is inputted to each of the OFDM demodulators, and the baseband signal of the frequency domain is diversity-synthesized by a second phase shifter.

OFDM receiver for easily synchronizing base band signal

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 tuner includes mixers that orthogonally convert a digital television signal located in high channels of the VHF band and a digital television signal located in a frequency range of 470 MHz to 608 MHz in the UHF band directly into baseband signals, and an oscillator that supplies local oscillation signals to the mixers. The oscillator is caused to oscillate at a frequency that is sixfold a frequency in the high channels of the VHF band or a frequency that is twofold a frequency in the frequency range of 470 MHz to 608 MHz in the UHF band. An oscillation signal having the twofold frequency is divided by two and an oscillation signal having the sixfold frequency is divided by six to generate local oscillation signals having orthogonal phases for both of these oscillation signals. The local oscillation signals having the divided frequencies are supplied to the mixers.

Direct conversion tuner capable of receiving digital television signals in UHF band and VHF band

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

A balanced gain control amplifier contains first and second transistors differentially connected to each other and having their emitters connected to a first current source. The balanced gain control amplifier also contains third and fourth transistors differentially connected to each other and having their emitters connected to a second constant current source. The collectors of the first and fourth transistors are connected to a power terminal through a common first load resistor, and the collectors of the second and third transistors are connected to the power terminal through a common second load resistor. A signal may be input between the bases of the first and third transistors and the bases of the second and fourth transistors. The current of the second constant current source is variable in a range no more than the current value of the first constant current source.

Balanced variable gain amplifier capable of achieving performance by low source voltage

A television tuner has a high frequency tuning circuit, a high frequency amplifier, a mixer, and an oscillating section. The tuning circuit is made up of an inductor and plural capacitors and at least one of the capacitors is selected and connected in parallel with the inductor; and the oscillating section has at least plural oscillators which are included in an integrated circuit. In the integrated circuit, the oscillators respectively have variable capacitors to vary a frequency of a local oscillation signal. Groups into which a receiving frequency band is divided correspond to the oscillators on the basis of one oscillator per group; and each of the oscillators generates local oscillation frequencies depending on television signals in the corresponding group.

Television tuner which operates at low voltage

A dual-band frequency converter unit, for selectively performing frequency conversion between a 2.4-GHz high-frequency-band signal or a 5-GHz high-frequency-band signal and a baseband signal by frequency mixing, includes a local oscillator for generating a local oscillation signal; a first frequency divider for generating a half-frequency signal of the local oscillation signal; and a second frequency divider for generating a quarter-frequency signal of the local oscillation signal. Frequency conversion between the 2.4-GHz high-frequency-band signal and the baseband signal is performed by frequency mixing using the half-frequency signal of the local oscillation signal. Frequency conversion between the 5-GHz high-frequency-band signal and the baseband signal is performed by frequency mixing using the local oscillation signal and the quarter-frequency signal of the local oscillation signal.

Dual-band frequency converter unit with high operability

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

A mixer has a first transistor and a second transistor which constitute a balanced oscillation circuit with their respective emitters connected with each other; a third transistor whose emitter is connected with the emitter of the first transistor; and a fourth transistor whose emitter is connected with the emitter of the second transistor. A first signal is inputted between a base of the third transistor and a base of the fourth transistor in a balanced way; and the third transistor and the fourth transistor mix an oscillation signal with the first signal and a second signal is outputted from the third transistor and the fourth transistor in a balanced way.

Mixer which assures satisfactory performance even at low supply voltage

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

An FM demodulator for reproducing data by performing FM demodulation of a received RF signal in a Bluetooth transmission system is provided. The FM demodulator includes a frequency discrimination unit and a level determination unit. The FM demodulator frequency-discriminates the RF signal, performs digital conversion of the discriminated RF signal, and outputs converted data. The level determination unit performs level comparison of current input-data, supplied from the frequency discrimination unit in the latest clock period, with last input-data, supplied from the frequency discrimination unit in the immediately preceding clock period, determines a logic state of the current input-data based on the result of the level comparison, and reproduces data in accordance with the determined logic state.

FM demodulator capable of providing demodulated data with high determination accuracy

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

Band characteristics between reception bands or reception channels are uniformed. There is provided a television tuner comprising a first tuning circuit which can be tuned to a television channel frequency in a first frequency band, a first amplification circuit for amplifying an output signal from the first tuning circuit, a second tuning circuit which can be tuned to a television channel frequency in a second frequency band, and a second amplification circuit for amplifying an output signal from the second tuning circuit, wherein, to at least one of the first and second tuning circuits, a damper resistor for decreasing Q of the tuning circuit when the tuning circuit is tuned to a frequency in a low-frequency band including each lowest channel in the first or second frequency band is connected.

Growing community of inventors

Fukushima-ken, Japan

Takeo Suzuki