Patents by Inventor Takafumi Yamaji
Takafumi Yamaji has filed for patents to protect the following inventions. This listing includes patent applications that are pending as well as patents that have already been granted by the United States Patent and Trademark Office (USPTO).
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Patent number: 9281830Abstract: A radio apparatus includes a first receiver that is a processing unit for amplifying and frequency converting a radio signal received via an antenna, thereby outputting an IF signal; a detector unit for detecting a preamble signal from the IF signal; a second receiver for amplifying and quadrature demodulating the radio signal, thereby generating an I-signal and a Q-signal; a demodulator unit for demodulating the I-signal and Q-signal to generate a data signal; and a control unit for halting the operation of the first receiver and further activating the second receiver when the detector unit detects the preamble signal and for activating the first receiver and halting the operation of the second receiver when the demodulator unit completes the demodulation of the I-signal and Q-signal.Type: GrantFiled: March 15, 2012Date of Patent: March 8, 2016Assignee: KABUSHIKI KAISHA TOSHIBAInventors: Shoji Otaka, Takafumi Yamaji, Tsutomu Sugawara, Yasuhiko Tanabe, Masahiro Hosoya, Hiroki Sakurai
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Patent number: 9099959Abstract: According to one embodiment, there is provided a fractional frequency dividing circuit including an integral frequency dividing circuit and an adjustment circuit. The integral frequency dividing circuit is configured to convert a reference signal to K (K is a positive integer) phase signals. Each of the K phase signals has a frequency of one nth (n is a positive integer) of the reference signal and has different phases from each other. The adjustment circuit is configured to weighting-add a plurality of signals corresponding to the K phase signals and generate a fractional-frequency-divided signal. The fractional-frequency-divided signal has a frequency of m times (m is a positive integer that is not multiplies of n) of each of the plurality of phase signals.Type: GrantFiled: January 29, 2014Date of Patent: August 4, 2015Assignee: Kabushiki Kaisha ToshibaInventors: Takafumi Yamaji, Tsuneo Suzuki
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Patent number: 8994436Abstract: According to one embodiment, there is provided a semiconductor device including a first amplifier and a second amplifier. The first amplifier has an input terminal to receive a first signal and an output terminal to output a second signal. The second amplifier is configured to receive the first signal and a correction data, to generate a correction signal according to the first signal and the correction data, and to output the generated correction signal to the output terminal of the first amplifier so as to add the first signal and the generated correction signal.Type: GrantFiled: March 20, 2013Date of Patent: March 31, 2015Assignee: Kabushiki Kaisha ToshibaInventors: Takafumi Yamaji, Yosuke Ogasawara
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Publication number: 20150055726Abstract: According to one embodiment, there is provided a fractional frequency dividing circuit including an integral frequency dividing circuit and an adjustment circuit. The integral frequency dividing circuit is configured to convert a reference signal to K (K is a positive integer) phase signals. Each of the K phase signals has a frequency of one nth (n is a positive integer) of the reference signal and has different phases from each other. The adjustment circuit is configured to weighting-add a plurality of signals corresponding to the K phase signals and generate a fractional-frequency-divided signal. The fractional-frequency-divided signal has a frequency of m times (m is a positive integer that is not multiplies of n) of each of the plurality of phase signals.Type: ApplicationFiled: January 29, 2014Publication date: February 26, 2015Applicant: KABUSHIKI KAISHA TOSHIBAInventors: Takafumi Yamaji, Tsuneo Suzuki
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Patent number: 8958767Abstract: A radio apparatus includes an antenna; an amplifier that amplifies a radio signal, received via the antenna; a first mixer that frequency converts the amplified radio signal to generate a first analog signal; a first A/D converter that converts the first analog signal to generate a first digital signal; a second mixer that frequency converts the amplified signal to generate a second analog signal; a second A/D converter means that converts the second analog signal to generate a second digital signal; a demodulator means that demodulates the first and second digital signals to generate a demodulated signal; a detector that detects a preamble from the first digital signal; and a control means that halts the second mixer and second A/D converter during the wait for the radio signal and that activates the second mixer and second A/D converter when the detector detects the preamble.Type: GrantFiled: March 16, 2012Date of Patent: February 17, 2015Assignee: Kabushiki Kaisha ToshibaInventors: Shoji Otaka, Takafumi Yamaji, Tsutomu Sugawara, Yasuhiko Tanabe, Masahiro Hosoya, Hiroki Sakurai
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Patent number: 8659454Abstract: A time error estimating device for estimating a sampling time error of each of a plurality of sampling circuits when the sampling circuits generates a plurality of sampling output signals by performing sampling at timings shifted from one another has correlators each configured to obtain a correlation value representing a similarity between the sampling output signals, and a weight adder configured to estimate the sampling time error of the sampling circuits, based on a result obtained by adjusting a weight on the correlation value.Type: GrantFiled: March 20, 2012Date of Patent: February 25, 2014Assignee: Kabushiki Kaisha ToshibaInventors: Tomohiko Sugimoto, Takafumi Yamaji, Junya Matsuno, Masanori Furuta
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Publication number: 20140043088Abstract: According to one embodiment, there is provided a semiconductor device including a first amplifier and a second amplifier. The first amplifier has an input terminal to receive a first signal and an output terminal to output a second signal. The second amplifier is configured to receive the first signal and a correction data, to generate a correction signal according to the first signal and the correction data, and to output the generated correction signal to the output terminal of the first amplifier so as to add the first signal and the generated correction signal.Type: ApplicationFiled: March 20, 2013Publication date: February 13, 2014Inventors: Takafumi YAMAJI, Yosuke OGASAWARA
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Patent number: 8502712Abstract: According to one embodiment, an analogue to digital converter converts an analogue input signal to a digital output signal. The converter includes an analogue to digital converting unit, a multiplexer, a pseudo-alias signal generator, a gain controller, and an alias signal compensator. The analogue to digital converting unit converts the analogue input signal to a plurality of digital signals. The multiplexer sequentially selects one of the digital signals and outputs the selected digital signal as a multiplexer output. The pseudo-alias signal generator generates a plurality of pseudo-alias signals from the digital signals. The pseudo-alias signal simulates an alias signal component in the multiplexer output. The gain controller generates a plurality of gain control signals by using the pseudo-alias signals. The gain control signal controls gain of the digital output signal. The alias signal compensator compensates the alias signal component by using the gain control signals.Type: GrantFiled: March 20, 2012Date of Patent: August 6, 2013Assignee: Kabushiki Kaisha ToshibaInventors: Naoya Waki, Junya Matsuno, Takafumi Yamaji, Masanori Furuta
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Publication number: 20130076544Abstract: According to one embodiment, an analogue to digital converter converts an analogue input signal to a digital output signal. The converter includes an analogue to digital converting unit, a multiplexer, a pseudo-alias signal generator, a gain controller, and an alias signal compensator. The analogue to digital converting unit converts the analogue input signal to a plurality of digital signals. The multiplexer sequentially selects one of the digital signals and outputs the selected digital signal as a multiplexer output. The pseudo-alias signal generator generates a plurality of pseudo-alias signals from the digital signals. The pseudo-alias signal simulates an alias signal component in the multiplexer output. The gain controller generates a plurality of gain control signals by using the pseudo-alias signals. The gain control signal controls gain of the digital output signal. The alias signal compensator compensates the alias signal component by using the gain control signals.Type: ApplicationFiled: March 20, 2012Publication date: March 28, 2013Applicant: KABUSHIKI KAISHA TOSHIBAInventors: Naoya Waki, Junya Matsuno, Takafumi Yamaji, Masanori Furuta
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Publication number: 20130076545Abstract: A time error estimating device for estimating a sampling time error of each of a plurality of sampling circuits when the sampling circuits generates a plurality of sampling output signals by performing sampling at timings shifted from one another has correlators each configured to obtain a correlation value representing a similarity between the sampling output signals, and a weight adder configured to estimate the sampling time error of the sampling circuits, based on a result obtained by adjusting a weight on the correlation value.Type: ApplicationFiled: March 20, 2012Publication date: March 28, 2013Applicant: KABUSHIKI KAISHA TOSHIBAInventors: Tomohiko Sugimoto, Takafumi Yamaji, Junya Matsuno, Masanori Furuta
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Publication number: 20120214434Abstract: A radio apparatus includes a first receiver that is a processing unit for amplifying and frequency converting a radio signal received via an antenna, thereby outputting an IF signal; a detector unit for detecting a preamble signal from the IF signal; a second receiver for amplifying and quadrature demodulating the radio signal, thereby generating an I-signal and a Q-signal; a demodulator unit for demodulating the I-signal and Q-signal to generate a data signal; and a control unit for halting the operation of the first receiver and further activating the second receiver when the detector unit detects the preamble signal and for activating the first receiver and halting the operation of the second receiver when the demodulator unit completes the demodulation of the I-signal and Q-signal.Type: ApplicationFiled: March 15, 2012Publication date: August 23, 2012Applicant: Kabushiki Kaisha TOSHIBAInventors: Shoji OTAKA, Takafumi Yamaji, Tsutomu Sugawara, Yasuhiko Tanabe, Masahiro Hosoya, Hiroki Sakurai
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Publication number: 20120208483Abstract: A radio apparatus includes an antenna; an amplifier that amplifies a radio signal, received via the antenna; a first mixer that frequency converts the amplified radio signal to generate a first analog signal; a first A/D converter that converts the first analog signal to generate a first digital signal; a second mixer that frequency converts the amplified signal to generate a second analog signal; a second A/D converter means that converts the second analog signal to generate a second digital signal; a demodulator means that demodulates the first and second digital signals to generate a demodulated signal; a detector that detects a preamble from the first digital signal; and a control means that halts the second mixer and second A/D converter during the wait for the radio signal and that activates the second mixer and second A/D converter when the detector detects the preamble.Type: ApplicationFiled: March 16, 2012Publication date: August 16, 2012Applicant: KABUSHIKI KAISHA TOSHIBAInventors: Shoji OTAKA, Takafumi Yamaji, Tsutomu Sugawara, Yasuhiko Tanabe, Masahiro Hosoya, Hiroki Sakurai
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Patent number: 7884749Abstract: An A/D converting apparatus includes a first A/D converter to sample an analog input signal having a D/A converter to generate a comparative signal for successive comparison with the analog input signal, a signal generator generate a differential signal between the analog input signal and the comparative signal, and a comparator to compare the comparative signal with a standard value to generate a first digital signal exhibiting high-order bit; an amplifier to amplify the differential signal to generate a residue signal; and a second A/D converter to sample the residue signal to generate a second digital signal exhibiting low-order bit.Type: GrantFiled: January 6, 2009Date of Patent: February 8, 2011Assignee: Kabushiki Kaisha ToshibaInventors: Masanori Furuta, Tomohiko Ito, Takafumi Yamaji, Tetsuro Itakura
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Patent number: 7842400Abstract: The present invention provides a surface treated steel sheet including a steel sheet; a plating layer containing at least one metal selected from the group consisting of zinc and aluminum on a surface of the steel sheet; and a film on the plating layer, the film containing at least one metal selected from the group consisting of Al, Mg, and Zn, a tetravalent vanadium compound, and a phosphoric acid group. This surface treated steel sheet exhibits excellent corrosion resistance and excellent surface appearance without containing hazardous substances, such as hexavalent chromium, in the film.Type: GrantFiled: July 28, 2004Date of Patent: November 30, 2010Assignee: JFE Steel CorporationInventors: Takafumi Yamaji, Reiko Yamaji, legal representative, Akira Matsuzaki, Kazuhisa Okai, Keiji Yoshida, Masaaki Yamashita, Yuichi Fukushima, Toshiyuki Okuma
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Publication number: 20100233986Abstract: A receiver includes a high-frequency filter which extracts, from a radio signal, a high-frequency signal, a first frequency converter which performs frequency conversion on the high-frequency signal using a first local signal, to obtain a first baseband signal, a second frequency converter which performs frequency conversion on the high-frequency signal using a second local signal, to obtain a second baseband signal, the second local signal having a frequency equal to an integral multiple of a frequency of the first local signal, and a subtraction processing unit configured to multiply the second baseband signal by a control coefficient for amplitude adjustment to obtain a product signal, and subtract the product signal from the first baseband signal to obtain a residual signal.Type: ApplicationFiled: October 15, 2009Publication date: September 16, 2010Applicant: KABUSHIKI KAISHA TOSHIBAInventors: Takafumi Yamaji, Junya Matsuno, Hiromitsu Aoyama
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Publication number: 20100150270Abstract: A signal processing circuit includes a decimation filter which down-samples over-sampled first three-phase digital signals to obtain second three-phase digital signals, and a converter which subjects the second three-phase digital signals to a three-phase to IQ conversion, and obtains orthogonal digital signals.Type: ApplicationFiled: September 14, 2009Publication date: June 17, 2010Applicant: KABUSHIKI KAISHA TOSHIBAInventors: Masanori Furuta, Takafumi Yamaji
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Publication number: 20100151800Abstract: A communication device includes: a first oscillator to generate a local signal based on a control signal for regulating at least one of phase oise and jitter in the local signal; a frequency converter to convert a first signal having first frequency to a second signal having second frequency by using the local signal; a filter to remove undesired signal component from the second signal and output a third signal; and a controller to generate the control signal based on the second signal and the third signal.Type: ApplicationFiled: September 14, 2009Publication date: June 17, 2010Applicant: KABUSHIKI KAISHA TOSHIBAInventors: Ippei Akita, Takafumi Yamaji, Akihide Sai
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Publication number: 20100112971Abstract: A receiver includes a multiphase mixer that multiplies a received radio signal by multiphase local signals the number of which is the same as an integer having a first prime factor and a second prime factor different from the first prime factor, and generates first multiphase baseband signals the number of which is the same as the integer, a first processing circuit that suppresses common modes for first multiphase signal groups formed by dividing the first multiphase baseband signals into groups of signals the number of which is the same as the first prime factor, and generates second multiphase baseband signals, and a second processing circuit that suppresses common modes for second multiphase signal groups formed by dividing the second multiphase baseband signals into groups of signals the number of which is the same as the second prime factor, and generates third multiphase baseband signals.Type: ApplicationFiled: July 15, 2009Publication date: May 6, 2010Applicant: KABUSHIKI KAISHA TOSHIBAInventors: Junya Matsuno, Takafumi Yamaji, Tetsuro Itakura
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Patent number: 7710301Abstract: According to an embodiment of the invention, there is provided a digital/analog converter includes: a decoder that converts a (n?1)-phase input digital signal to a n-phase output digital signal; and a signal generating unit that generates analog signals according to the n-phase output digital signal.Type: GrantFiled: May 31, 2007Date of Patent: May 4, 2010Assignee: Kabushiki Kaisha ToshibaInventors: Takeshi Ueno, Takafumi Yamaji
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Publication number: 20090245418Abstract: A transmitter includes a signal generator to generate a digital baseband signal corresponding to a signal to be transmitted, a digital-analog converter to convert the digital baseband signal into an analog baseband signal by operating in accordance with a clock signal, a subtracter to subtract a feedback baseband signal from the analog baseband signal to generate a residual signal, a loop filter to filter the residual signal by amplifying a low-frequency component and suppressing a high-frequency component, a modulator to modulate the filtered signal by multiplying the filtered signal, a power amplifier to amplify the modulated signal, a high frequency filter to filter the amplified modulated signal to obtain a transmit RF signal, the high frequency filter having a passband width narrower than a frequency of the clock signal, and a demodulator to demodulate a feedback RF signal which is divided from the transmit RF signal.Type: ApplicationFiled: March 13, 2009Publication date: October 1, 2009Inventor: Takafumi YAMAJI