Patents by Inventor Kazumi Shiikuma
Kazumi Shiikuma 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: 8198950Abstract: A power amplifier that amplifies an RF modulation signal containing an amplitude modulation component and a phase modulation component, including a polar modulator that outputs an amplitude component signal that is the amplitude modulation component of the RF modulation signal, a direct current power supply that outputs a direct current voltage, a pulse modulator that pulse-modulates the amplitude component signal, a pulse amplification circuit that amplifies a pulse modulation signal, a combining circuit that adds a direct current voltage that is outputted from the direct current power supply to an output signal of the pulse amplification circuit, a low pass filter that smoothens an output signal of the combining circuit, and an RF amplifier that not only amplifies the RF modulation signal, but also amplitude-modulates the amplified signal with an output signal of the low pass filter and outputs the resultant signal.Type: GrantFiled: October 1, 2009Date of Patent: June 12, 2012Assignee: NEC CorporationInventors: Shingo Yamanouchi, Kazuaki Kunihiro, Kazumi Shiikuma
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Patent number: 8157571Abstract: A high-frequency module includes: a shield cover of the high-frequency module; a coaxial connector which is fixed to an outer side surface of the shield cover; a center conductor of the coaxial connector which protrudes to the inside of a region of the high-frequency module; and a metal plate terminal which is mounted on a print wiring formed on a substrate. The shield cover is fixed to the substrate so as to cover the upper portion thereof, while the center conductor of the coaxial connector is fitted to the metal plate terminal so as to allow input and output of a high-frequency signal.Type: GrantFiled: May 26, 2009Date of Patent: April 17, 2012Assignee: NEC CorporationInventors: Keijirou Kadomatsu, Hiroshi Takahashi, Kazumi Shiikuma
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Publication number: 20110279180Abstract: An aspect of a power amplifier according to the present invention is a power amplifier that amplifies a modulated signal including amplitude modulated components and phase modulated components, the power amplifier including a first voltage source 21 that amplifies low-frequency components of the amplitude modulated components of the modulated signal to output a first voltage VC_L, a second voltage source 22 that amplifies high-frequency components of the amplitude modulated components of the modulated signal to output a second voltage VC_H, a current source 24 that amplifies amplitude components of the modulated signal to output a current, a combiner circuit 23 that combines the first voltage VC_L, the second voltage VC_H, and a current IM to generate a modulated power supply signal VOUT, and an RF amplifier 30 that amplifies a signal obtained by up-converting the modulated signal to a carrier frequency and outputs the amplified signal after modulating amplitude of the amplified signal by the modulated powerType: ApplicationFiled: January 27, 2010Publication date: November 17, 2011Applicant: NEC CORPORATIONInventors: Shingo Yamanouchi, Kazuaki Kunihiro, Kazumi Shiikuma
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Publication number: 20110241775Abstract: A radio frequency amplifier amplifies a modulation signal or its phase modulation component and outputs the resultant signal. A linear amplifier adds an output voltage to a power supply voltage supplied to the radio frequency amplifier, amplifies a difference between the output voltage and the amplitude modulation component, and outputs the resultant difference. A control signal generation section detects a direction in which an output current of the linear amplifying section flows and generates a pulse modulation signal according to the direction of the current. A switching amplifying section controls connection and disconnection of a DC current based on the pulse modulation signal as a control signal so as to perform switching amplification for an output signal of the linear amplifying section, add the resultant signal to a predetermined DC voltage, and supply the resultant signal as the power supply voltage to the radio frequency amplifier.Type: ApplicationFiled: December 16, 2009Publication date: October 6, 2011Inventors: Kazuaki Kunihiro, Shingo Yamanouchi, Kazumi Shiikuma
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Publication number: 20110163822Abstract: A power amplifier that amplifies an RF modulation signal containing an amplitude modulation component and a phase modulation component, including a polar modulator that outputs an amplitude component signal that is the amplitude modulation component of the RF modulation signal, a direct current power supply that outputs a direct current voltage, a pulse modulator that pulse-modulates the amplitude component signal, a pulse amplification circuit that amplifies a pulse modulation signal, a combining circuit that adds a direct current voltage that is outputted from the direct current power supply to an output signal of the pulse amplification circuit, a low pass filter that smoothens an output signal of the combining circuit, and an RF amplifier that not only amplifies the RF modulation signal, but also amplitude-modulates the amplified signal with an output signal of the low pass filter and outputs the resultant signal.Type: ApplicationFiled: October 1, 2009Publication date: July 7, 2011Inventors: Shingo Yamanouchi, Kazuaki Kunihiro, Kazumi Shiikuma
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Publication number: 20110104910Abstract: A high-frequency module includes: a shield cover of the high-frequency module; a coaxial connector which is fixed to an outer side surface of the shield cover; a center conductor of the coaxial connector which protrudes to the inside of a region of the high-frequency module; and a metal plate terminal which is mounted on a print wiring formed on a substrate. The shield cover is fixed to the substrate so as to cover the upper portion thereof, while the center conductor of the coaxial connector is fitted to the metal plate terminal so as to allow input and output of a high-frequency signal.Type: ApplicationFiled: May 26, 2009Publication date: May 5, 2011Inventors: Keijirou Kadomatsu, Hiroshi Takahashi, Kazumi Shiikuma
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Patent number: 7710202Abstract: An amplifier includes a carrier amplifier which performs signal amplification at all times, a peak amplifier which operates only at a time when the high electric power is outputted, a combiner which combines the output from the carrier amplifier and the peak amplifier, and a distributor which distributes an input signal to the carrier amplifier and the peak amplifier. The carrier amplifier and the peak amplifier are included in a single package transistor.Type: GrantFiled: September 29, 2008Date of Patent: May 4, 2010Assignee: NEC CorporationInventor: Kazumi Shiikuma
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Patent number: 7649413Abstract: A high-frequency power amplifier of the present invention comprises a power supply unit for including a transistor for switching whose drain electrode—source electrode or collector electrode—emitter electrode are on/off controlled according to a pulse signal corresponding to an envelope signal of a high-frequency signal applied to a gate electrode or to a base electrode, and for generating a voltage corresponding to the envelope signal by means of on/off operation of the transistor for switching; and a transistor for power amplification which is a source electrode grounded type or an emitter electrode grounded type, to which a voltage generated by the power supply unit is supplied as an operating voltage, in which the high-frequency signal is applied to the gate electrode or to the base electrode. Further, the transistor for switching in the power supply unit and the transistor for power amplification are arranged so that the source electrodes or the emitter electrodes are commonly connected in one package.Type: GrantFiled: October 30, 2007Date of Patent: January 19, 2010Inventor: Kazumi Shiikuma
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Publication number: 20090045878Abstract: An amplifier includes a carrier amplifier which performs signal amplification at all times, a peak amplifier which operates only at a time when the high electric power is outputted, a combiner which combines the output from the carrier amplifier and the peak amplifier, and a distributor which distributes an input signal to the carrier amplifier and the peak amplifier. The carrier amplifier and the peak amplifier are included in a single package transistor.Type: ApplicationFiled: September 29, 2008Publication date: February 19, 2009Applicant: NEC CorporationInventor: Kazumi Shiikuma
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Patent number: 7453320Abstract: An amplifier comprises a carrier amplifier which performs signal amplification at all times, a peak amplifier which operates only at a time when the high electric power is outputted, a combiner which combines the output from the carrier amplifier and the peak amplifier, and a distributor which distributes an input signal to the carrier amplifier and the peak amplifier. The carrier amplifier and the peak amplifier are included in a single package transistor.Type: GrantFiled: September 17, 2004Date of Patent: November 18, 2008Assignee: NEC CorporationInventor: Kazumi Shiikuma
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Publication number: 20080111631Abstract: A high-frequency power amplifier of the present invention comprises a power supply unit for including a transistor for switching whose drain electrode-source electrode or collector electrode-emitter electrode are on/off controlled according to a pulse signal corresponding to an envelope signal of a high-frequency signal applied to a gate electrode or to a base electrode, and for generating a voltage corresponding to the envelope signal by means of on/off operation of the transistor for switching; and a transistor for power amplification which is a source electrode grounded type or an emitter electrode grounded type, to which a voltage generated by the power supply unit is supplied as an operating voltage, in which the high-frequency signal is applied to the gate electrode or to the base electrode. Further, the transistor for switching in the power supply unit and the transistor for power amplification are arranged so that the source electrodes or the emitter electrodes are commonly connected in one package.Type: ApplicationFiled: October 30, 2007Publication date: May 15, 2008Inventor: Kazumi Shiikuma
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Patent number: 7315207Abstract: Pre-distortion compensation circuits (11, 12) are disposed at stages previous to carrier amplifier 13 and peak amplifier 14, respectively. Pre-distortion compensation circuit (11) has such characteristics that compensate carrier amplifier (13) for a distortion characteristically produced on the operation thereof, particularly, an amplitude-phase (AM-PM) distortion, while pre-distortion compensation circuit (12) has such characteristics that compensate peak amplifier (14) for a distortion characteristically produced on the operation thereof, particularly, an AM-PM distortion. Thus, the Doherty amplifier is also compensated for its own AM-PM distortion characteristic to accomplish a low distortion characteristic and implement an ideal power combining operation thereof.Type: GrantFiled: December 22, 2003Date of Patent: January 1, 2008Assignee: NEC CorporationInventor: Kazumi Shiikuma
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Patent number: 7295064Abstract: The present invention is intended to provide a Doherty amplifier that can accomplish a linear amplifying and a power combining operation closer to the ideal in a simple configuration. The configuration comprises gain compensator 6 that is composed of a parallel circuit made of an anti-parallel diode and a resistor that is disposed at a position ahead of peak amplifier 4 included in the Doherty amplifier. Setting the gain in gain compensator 6 allows peak amplifier 4 to be compensated for the operation characteristic, when peak amplifier 4 is operating, based on the gm characteristic of peak amplifier 4.Type: GrantFiled: December 17, 2003Date of Patent: November 13, 2007Assignee: NEC CorporationInventors: Kazumi Shiikuma, Junichi Mizoguchi
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Publication number: 20070252649Abstract: In a constant amplitude wave-combining type amplifier for splitting a single input signal into two parts by a distributor 1, amplifying the split signal parts by first and second amplifiers 3a, 3b and then combining output signals amplified thereby, the amplifiers 3a, 3b comprise at least two amplifier elements accommodated in a single package. Also, the amplifier elements constituting the first and second amplifiers 3a, 3b are packaged in a close relationship to each other. Moreover, the amplifier elements constituting the first and second amplifiers 3a, 3b may be either field effect transistors or bipolar transistors.Type: ApplicationFiled: April 26, 2007Publication date: November 1, 2007Inventor: Kazumi SHIIKUMA
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Patent number: 7262656Abstract: A circuit is disclosed for operating Doherty amplifiers in parallel in a small size circuit and at a low cost while reducing transmission loss and preventing a narrowed band. The circuit has a plurality of Doherty amplifiers and a signal combiner. Each of the plurality of Doherty amplifiers is applied with a distributed input signal which is amplified and delivered by the Doherty amplifier. The signal combiner is made up of a transmission line transformer, is connected to the outputs of the Doherty amplifiers and to its output terminal. The signal combiner has an impedance as viewed from the Doherty amplifiers, which represents an optimal load for the Doherty amplifiers, and an impedance as viewed from the output terminal, which is equal to the characteristic impedance of a transmission line connected to the output terminal. The signal combiner combines the outputs of the Doherty amplifiers and delivers the resulting output from the output terminal.Type: GrantFiled: August 17, 2005Date of Patent: August 28, 2007Assignee: NEC CorporationInventor: Kazumi Shiikuma
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Publication number: 20070103237Abstract: An amplifier comprises a carrier amplifier which performs signal amplification at all times, a peak amplifier which operates only at a time when the high electric power is outputted, a combiner which combines the output from the carrier amplifier and the peak amplifier, and a distributor which distributes an input signal to the carrier amplifier and the peak amplifier. The carrier amplifier and the peak amplifier are included in a single package transistor.Type: ApplicationFiled: September 17, 2004Publication date: May 10, 2007Applicant: NEC CORPORATIONInventor: Kazumi Shiikuma
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Publication number: 20060114064Abstract: Pre-distortion compensation circuits (11, 12) are disposed at stages previous to carrier amplifier 13 and peak amplifier 14, respectively. Pre-distortion compensation circuit (11) has such characteristics that compensate carrier amplifier (13) for a distortion characteristically produced on the operation thereof, particularly, an amplitude-phase (AM-PM) distortion, while pre-distortion compensation circuit (12) has such characteristics that compensate peak amplifier (14) for a distortion characteristically produced on the operation thereof, particularly, an AM-PM distortion. Thus, the Doherty amplifier is also compensated for its own AM-PM distortion characteristic to accomplish a low distortion characteristic and implement an ideal power combining operation thereof.Type: ApplicationFiled: December 22, 2003Publication date: June 1, 2006Inventor: Kazumi Shiikuma
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Publication number: 20060055458Abstract: The present invention is intended to provide a Doherty amplifier that can accomplish a linear amplifying and a power combining operation closer to the ideal in a simple configuration. The configuration comprises gain compensator 6 that is composed of a parallel circuit made of an anti-parallel diode and a resistor that is disposed at a position ahead of peak amplifier 4 included in the Doherty amplifier. Setting the gain in gain compensator 6 allows peak amplifier 4 to be compensated for the operation characteristic, when peak amplifier 4 is operating, based on the gm characteristic of peak amplifier 4.Type: ApplicationFiled: December 17, 2003Publication date: March 16, 2006Applicant: NEC CorporationInventors: Kazumi Shiikuma, Junichi Mizoguchi
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Publication number: 20060044060Abstract: A circuit is disclosed for operating Doherty amplifiers in parallel in a small size circuit and at a low cost while reducing transmission loss and preventing a narrowed band. The circuit has a plurality of Doherty amplifiers and a signal combiner. Each of the plurality of Doherty amplifiers is applied with a distributed input signal which is amplified and delivered by the Doherty amplifier. The signal combiner is made up of a transmission line transformer, is connected to the outputs of the Doherty amplifiers and to its output terminal. The signal combiner has an impedance as viewed from the Doherty amplifiers, which represents an optimal load for the Doherty amplifiers, and an impedance as viewed from the output terminal, which is equal to the characteristic impedance of a transmission line connected to the output terminal. The signal combiner combines the outputs of the Doherty amplifiers and delivers the resulting output from the output terminal.Type: ApplicationFiled: August 17, 2005Publication date: March 2, 2006Inventor: Kazumi Shiikuma
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Patent number: 6792050Abstract: A base band signal is frequency limited by a band limiting circuit 1. The waveform of this output signal rises and falls smoothly against a time axis. A driving circuit 2 functions as a buffer amplifier with voltage gain of 1 between the band limiting circuit 1 and ASK modulation circuit 3, and the output voltage wave is equal to the output waveform of the band limiting circuit 1. The ASK modulation circuit 3 turns on/off a field effect transistor 61 by the output signal voltage from the driving circuit 2, thereby discontinuing the carrier of the microwave band to be externally entered and performing ASK modulation (binary ASK), and provides a desired ASK modulated waveform as a result.Type: GrantFiled: July 27, 1999Date of Patent: September 14, 2004Assignee: NEC CorporationInventors: Kazumi Shiikuma, Toyosaka Yamasaki