Abstract: Gain setting can be performed at high speed while reducing DC offset due to a filter cutoff frequency changeover without the need for input signal muting. A filter circuit having first and second filters is capable of allowing settings of first and second cutoff frequencies. First and second filter switch circuits and a charging circuit including a charging resistor and a charging switch are provided. For a first time period, the first switch circuit is controllably turned on while the second switch circuit is controllably turned off, thereby providing the first filter function. For a second time period, the first switch circuit is controllably turned off while the second switch circuit is controllably turned on, thereby providing the second filter function. For the first time period, the charging switch is controllably turned on so that the second capacitor is charged via the charging resistor.

Abstract: A receiving circuit is provided for performing reception of a plurality of band signals and suppression of blockers that remain in the plurality of band signals being received and converted in frequency. The receiving circuit includes a first low-pass filter that has a first pole position to suppress blockers remaining in a received signal by the first pole position, and a second low-pass filter that has a second pole position to suppress blockers remaining in a signal that has passed through said first low-pass filter by the second pole position. A switch that switches on/off an input-output path including the filters so that the received signal passes through said first filter without passing through the second filter when receiving a first band signal, while the received signal passes through both filters when receiving a second band signal different from the first band signal.

Abstract: Within a short-distance wireless transmitting apparatus for use of TV, for transmitting video without interruption and with low power consumption, a transmitter portion having a reception frequency differing from a transmission frequency is provided on a station side having a video source, and a receiver portion for receiving the frequency corresponding to a reception frequency band of the station side and also a transmitter portion for transmitting the frequency corresponding to a reception frequency band of the station side are provided on a panel side for displaying, in the structure thereof, wherein transmission/reception can be operated, simultaneously, by FDD separating in frequency for transmission. The frequency of the transmitter on the panel side is determined upon basis of a scan result, while scanning a vacant frequency on the station side, and thereby enabling to escape from an interference from other system, when the panel executes the transmission, in the structure thereof.

Abstract: The present invention is a receiving circuit used for a cellular phone that is reduced in size and can realize low power consumption. In a signal reception circuit that is used in a cellular phone that perform transmission and reception of a plurality of band wireless signals and includes a low-pass filter for removing blockers unnecessary for signal reception, the low-pass filter 104 is composed of a plurality of filters composed of a plurality of different circuit configurations and having a plurality of different pole positions, switching between a filter for blocker removal and a filter configuration with reduced sensitivity degradation is performed by combining a plurality of filters for each signal reception band, and by performing power-off of an unnecessary filter portion in the filter configuration, power consumption is reduced.

Abstract: A technique of frequency hopping communication capable of high-speed switching of a plurality of signals having ultra-wide band 528 MHz bandwidth at high-speed and setting and switching a band center frequency and the number of bands arbitrary is provided. A radio transceiver has a frequency hopping communication function of UWB system for switching the ultra wide band signal. In the device, high-speed frequency hopping is realized by controlling an SSB mixer in a local oscillator circuit and switching the frequency of a DDS. The device sets NCO data to the DDS and switches a quadrature phase signal of an output, and switches a signal input of an input terminal of the SSB mixer by a control of a phase switching switch. One of a sum component and a difference component of a mixture of first and second quadrature phase signals is outputted from the output terminal of the SSB mixer.

Abstract: A cellular phone having a telephone communication unit and a data communication unit is provided with the function of notifying a user of emergency data communication immediately even when the emergency data communication was received while a call was in progress. There is provided a communication terminal equipment according to the present invention, which includes a data communication unit which receives emergency data communication, a display unit which displays the contents of the received data communication thereon, and a communication unit which communicates with a base station by phone or the like. The communication unit establishes a call link through a cellular phone network, and the data communication unit allows received data to interrupt a call upon emergency, displays it on the display unit and notifies a user that emergency data has been received.

Abstract: The receiver includes a low noise amplifier, a local signal generator, a first mixer, a second mixer, a first amplifier, a second amplifier, a first A/D converter, a second A/D converter, and a signal level detection unit. A detection signal from at least one terminal of the first A/D converter is supplied to an input terminal of the signal level detection unit, thereby generating a reception start signal from the output terminal. Before an RF reception signal is received, a first signal processing unit containing the first mixer, the first amplifier, and the first A/D converter is controlled to an active state, and a second signal processing unit containing the second mixer, the second amplifier, and the second A/D converter is controlled to a low power consumption state. After the RF reception signal is received, the second signal processing unit is controlled to the active state.

Abstract: A filter circuit includes first capacitors, second capacitors capable of altering a cutoff frequency by being connected in parallel with the first capacitors, first switches for connecting the second capacitors in parallel with the first capacitors, and charging circuits for the second capacitors. The charging circuits include second switches, and resistances for attenuating the amplitudes of input voltages to be fed to the second capacitors, by being connected in series with the second capacitors. The second capacitors are charged through the resistances in a state where the first switches are turned OFF and where the second switches are turned ON. Thus, a DC offset which is ascribable to the cutoff frequency switching of a filter is reduced.

Abstract: In a signal receiving circuit of a direct conversion system applied with a semiconductor integrated circuit for radio communication having a PLL requiring a clock signal, an LNA requiring low-noise receiving characteristics, and others, a variable coupling line is provided between clock signal buffers and at an input stage of the PLL, so that coupling between the variable coupling line and an input terminal of the LNA and coupling between the variable coupling line and a GND terminal of the LNA are made equal to each other at frequencies of higher harmonic waves of a clock signal. When the input terminal and the GND terminal of the LNA are excited at the same phase, since no output occurs at an output terminal of the LNA, an output of the LNA does not contain any higher harmonic wave of a clock signal.

Abstract: The present invention is a receiving circuit used for a cellular phone that is reduced in size and can realize low power consumption. In a signal reception circuit that is used in a cellular phone that perform transmission and reception of a plurality of band wireless signals and includes a low-pass filter for removing blockers unnecessary for signal reception, the low-pass filter 104 is composed of a plurality of filters composed of a plurality of different circuit configurations and having a plurality of different pole positions, switching between a filter for blocker removal and a filter configuration with reduced sensitivity degradation is performed by combining a plurality of filters for each signal reception band, and by performing power-off of an unnecessary filter portion in the filter configuration, power consumption is reduced.

Abstract: When switching over from a portable telephone system of 800 MHz band to a UWB communication system of 9 GHz band, depending upon a signal for changing over a high pass filter and a low pass filter, a reactance element, which is determined to be matching with a load Z of the high pass filter, is connected to an output terminal of a transmitting power amplifier. With this, it is possible to achieve a multi-band or multi-mode wireless receiver of using a frequency band from 800 MHz to 10 GHz, without an enlargement of a circuit scale and an increase of costs.

Abstract: A cellular phone having a telephone communication unit and a data communication unit is provided with the function of notifying a user of emergency data communication immediately even when the emergency data communication was received while a call was in progress. There is provided a communication terminal equipment according to the present invention, which includes a data communication unit which receives emergency data communication, a display unit which displays the contents of the received data communication thereon, and a communication unit which communicates with a base station by phone or the like. The communication unit establishes a call link through a cellular phone network, and the data communication unit allows received data to interrupt a call upon emergency, displays it on the display unit and notifies a user that emergency data has been received.

Abstract: A technique of frequency hopping communication capable of high-speed switching of a plurality of signals having ultra-wide band 528 MHz bandwidth at high-speed and setting and switching a band center frequency and the number of bands arbitrary is provided. A radio transceiver has a frequency hopping communication function of UWB system for switching the ultra wide band signal. In the device, high-speed frequency hopping is realized by controlling an SSB mixer in a local oscillator circuit and switching the frequency of a DDS. The device sets NCO data to the DDS and switches a quadrature phase signal of an output, and switches a signal input of an input terminal of the SSB mixer by a control of a phase switching switch. One of a sum component and a difference component of a mixture of first and second quadrature phase signals is outputted from the output terminal of the SSB mixer.

Abstract: In a signal receiving circuit of a direct conversion system applied with a semiconductor integrated circuit for radio communication having a PLL requiring a clock signal, an LNA requiring low-noise receiving characteristics, and others, a variable coupling line is provided between clock signal buffers and at an input stage of the PLL, so that coupling between the variable coupling line and an input terminal of the LNA and coupling between the variable coupling line and a GND terminal of the LNA are made equal to each other at frequencies of higher harmonic waves of a clock signal. When the input terminal and the GND terminal of the LNA are excited at the same phase, since no output occurs at an output terminal of the LNA, an output of the LNA does not contain any higher harmonic wave of a clock signal.

Abstract: A communication terminal device comprising a TV broadcasting tuner for receiving a TV broadcasting, a display device for displaying a video image of the received TV broadcasting, and a transceiver for communicating with a base station. The transceiver acquires base station information for an optional one of base station areas, and acquires a TV broadcasting frequency corresponding to the optional base station area. The TV broadcasting tuner receives the TV broadcasting at the acquired TV broadcasting frequency.

Abstract: There are provided a voltage-controlled oscillator and an RF-IC for W-CDMA, which are capable of ensuring a wide frequency range and improving oscillation stability. The voltage-controlled oscillator (RF-IC) includes: switching A and B inductors generating a magnetic interaction between resonant A and B inductors of a resonant circuit; and an A_NMOS, a B_NMOS, a C_NMOS, and D_NMOS as switch/load means having together a function of changing an inductance value by the magnetic interaction between the resonant A and B inductors and the switching A and B inductors and a function of serving as loads of the switching A and B inductors. The A_NMOS, the B_NMOS, the C_NMOS, and the D_NMOS are turned ON/OFF by a control signal so as to control the mutual induction, whereby the oscillation frequency is switched by changing the inductance value of the resonant circuit. Also, oscillation stability is improved by increasing the inductance value.

Abstract: A cellular phone having a telephone communication unit and a data communication unit is provided with the function of notifying a user of emergency data communication immediately even when the emergency data communication was received while a call was in progress. There is provided a communication terminal equipment according to the present invention, which includes a data communication unit which receives emergency data communication, a display unit which displays the contents of the received data communication thereon, and a communication unit which communicates with a base station by phone or the like. The communication unit establishes a call link through a cellular phone network, and the data communication unit allows received data to interrupt a call upon emergency, displays it on the display unit and notifies a user that emergency data has been received.

Abstract: A communication terminal device comprising a TV broadcasting tuner for receiving a TV broadcasting, a display device for displaying a video image of the received TV broadcasting, and a transceiver for communicating with a base station. The transceiver acquires base station information for an optional one of base station areas, and acquires a TV broadcasting frequency corresponding to the optional base station area. The TV broadcasting tuner receives the TV broadcasting at the acquired TV broadcasting frequency.