Abstract: A radio receiving system, which receives an input signal in a direct conversion receiving mode through the use of a plurality of cascaded channel filters, each including a complex coefficient filter, to obtain a desired waveform, wherein a center frequency of a preliminary channel filter corresponds more closely with the frequency of the desired waveform than a center frequency of a subsequent channel filter.

Abstract: A receiving circuit mainly available in a digital modulation type communication system having a plurality of channels, which is capable of reducing power in a receiving system, simplifying the circuit and reducing the power consumption. Upside and downside frequencies corresponding to a central value between channels are separately supplied from a local frequency signal generating circuit 4 to first and second frequency converting circuits 2, 3 so that two output signals are developed with respect to one of a desired wave, upside channel and downside channel. The desired wave present in common in the fist and second frequency converting circuits 2, 3 is extracted in a common wave extracting circuit 5, and a frequency offset of &ohgr;o existing in the output of the common wave extracting circuit 5 is removed a frequency offset circuit 6 and further an unnecessary frequency component is filtered by a filter 8.

Abstract: A radio receiving system includes an orthogonally-modulated waveform detection/channel filter section 4, an I signal root Nyquist filter 20, a Q signal root Nyquist filter 21, and a signal detection/demodulation section 25. The orthogonally-modulated waveform detection/channel filter section 4 further includes a first filter (a band pass filter) 2 which permits passage of only a signal at a frequency band assigned to a communications system from which the radio receiving system receives a signal; a sample-and-hold circuit 5; a Hilbert transformer 6; a first channel filter 7 through N-th channel filter 9; and a clock signal shaping/controlling section 15. The band pass filter 2 is provided with the characteristics which cancel the aperture effect due to a sampling operation, thus compensating for the aperture effect due to a sampling operation.

Abstract: A radio receiving system, which receives an input signal in a direct conversion receiving mode through the use of a plurality of cascaded channel filters, each including a complex coefficient filter, to obtain a desired waveform, wherein a center frequency of a preliminary channel filter corresponds more closely with the frequency of the desired waveform than a center frequency of a subsequent channel filter.

Abstract: A receiving circuit mainly available in a digital modulation type communication system having a plurality of channels, which is capable of reducing power in a receiving system, simplifying the circuit and reducing the power consumption. Upside and downside frequencies corresponding to a central value between channels are separately supplied from a local frequency signal generating circuit 4 to first and second frequency converting circuits 2, 3 so that two output signals are developed with respect to one of a desired wave, upside channel and downside channel. The desired wave present in common in the first and second frequency converting circuits 2, 3 is extracted in a common wave extracting circuit 5, and a frequency offset of &ohgr;o existing in the output of the common wave extracting circuit 5 is removed a frequency offset circuit 6 and further an unnecessary frequency component is filtered by a filter 8.

Abstract: Input port 101 is connected to output port 102 via open-circuited stub 107, first transmission line 105 and open-circuited stub 108. Coupling port 103 is connected to isolation port 104 via second transmission line 106 in electromagnetic coupling with first transmission line 105. Open-circuited stubs 107 and 108 have a stub length corresponding to ¼ wavelength in desired stop frequency. It is thereby possible to provide a directional coupler and directional coupling method enabling the miniaturization and harmonic spurious suppression effect with a low loss and with excellence even in microwave/millimeter wave band.

Abstract: A received signal obtained from an antenna is subjected to high-frequency amplification. The amplified signal is supplied to a first bandpass filter, which extracts only signals of all the channels of a communications system concerned while filtering out other radio signals. The extracted signals are frequency-converted by using a local oscillation frequency, and only a desired wave is passed by a second bandpass filter. The desired wave is supplied to a sample-and-hold circuit, which performs sampling according to the bandwidth-limiting sampling theorem. A resulting discrete signal is supplied to an I-axis-component and Q-axis-component separating circuits, where the polarity of sample values is inverted for every other clock pulse with respect to each of the I and Q axes to thereby effect Hilbert transform. Resulting two orthogonal components on a phase plane are supplied to a complex coefficient filter.

Abstract: A receiving circuit mainly available in a digital modulation type communication system having a plurality of channels, which is capable of reducing power in a receiving system, simplifying the circuit and reducing the power consumption. Upside and downside frequencies corresponding to a central value between channels are separately supplied from a local frequency signal generating circuit 4 to first and second frequency converting circuits 2, 3 so that two output signals are developed with respect to one of a desired wave, upside channel and downside channel. The desired wave present in common in the first and second frequency converting circuits 2, 3 is extracted in a common wave extracting circuit 5, and a frequency offset of &ohgr;o existing in the output of the common wave extracting circuit 5 is removed a frequency offset circuit 6 and further an unnecessary frequency component is filtered by a filter 8.

Abstract: A transmission output detecting circuit for use in a radio transmitter-receiver of a TDD communication system having a TDD switch for connecting a transmission system to an antenna system in a transmitting period and for connecting a reception system to the antenna system in a receiving period; comprising a detection means for detecting transmission output on the basis of leakage power of the TDD switch in the transmitting period. The transmission output can be detected with low power consumption without making the transmission power branch out.

Abstract: A multiband mobile unit communication apparatus is disclosed which comprises: an antenna for receiving L FRQ bands of M radio wave SIGs modulated by N modulating methods, M>L, M>N, N≧L; a frequency synthesizer for generating a LO SIG; an IF SIG generation CKT for generating M IF SIGs using the LO SIG, the FRQ synthesizer generating the LO SIG such that the M IF SIGs have the same intermediate FRQ; a SW CKT for selectively outputting N IF SIGs modulated by the N modulating methods respectively out of the M IF SIGs; N filters for filtering outputs of N IF SIGs from the SW CKT and outputting N filtered IF SIGs respectively; a SW responsive to a SW CONT signal for selectively outputting one of the N filtered IF SIGs; and a quadrature demodulator for quadrature-demodulating one of N filtered IF SIGs and outputting baseband SIG. Different frequency bands of received signals are converted into IF SIGs having the same intermediate frequency.

Abstract: A received signal obtained from an antenna is subjected to high-frequency amplification. The amplified signal is supplied to a first bandpass filter, which extracts only signals of all the channels of a communications system concerned while filtering out other radio signals. The extracted signals are frequency-converted by using a local oscillation frequency, and only a desired wave is passed by a second bandpass filter. The desired wave is supplied to a sample-and-hold circuit, which performs sampling according to the bandwidth-limiting sampling theorem. A resulting discrete signal is supplied to an I-axis-component and Q-axis-component separating circuits, where the polarity of sample values is inverted for every other clock pulse with respect to each of the I and Q axes to thereby effect Hilbert transform. Resulting two orthogonal components on a phase plane are supplied to a complex coefficient filter.

Abstract: A received signal obtained from an antenna is subjected to high-frequency amplification. The amplified signal is supplied to a first bandpass filter, which extracts only signals of all the channels of a communications system concerned while filtering out other radio signals. The extracted signals are frequency-converted by using a local oscillation frequency, and only a desired wave is passed by a second bandpass filter. The desired wave is supplied to a sample-and-hold circuit, which performs sampling according to the bandwidth-limiting sampling theorem. A resulting discrete signal is supplied to an I-axis-component and Q-axis-component separating circuits, where the polarity of sample values is inverted for every other clock pulse with respect to each of the I and Q axes to thereby effect Hilbert transform. Resulting two orthogonal components on a phase plane are supplied to a complex coefficient filter.

Abstract: A radio communication apparatus is designed for a plurality of different radio communication formats, one of which can be selected. The radio communication apparatus includes a fixed-gain IF amplifier and a variable-gain IF amplifier. One is selected out of the fixed-gain IF amplifier and the variable-gain IF amplifier as an effectively used IF amplifier in response to which of the radio communication formats is selected. The fixed-gain IF amplifier is selected as an effectively used IF amplifier when a narrow-band radio communication format is selected. The variable-gain IF amplifier is selected as an effectively used IF amplifier when a wide-band radio communication format is selected.

Abstract: A receiving circuit includes a first antenna 1, a second antenna 2, units 10 and 11 for generating a sum signal or a difference signal from signals of two paths received by the respective antennas, a unit 12 for giving delay to either an output of the sum signal generating unit or an output of the difference signal generating unit, a unit 13 for summationally combining an output of the delay unit and the signal of the not-delayed path, a desired-wave pass filter unit 14 for receiving an output of the summationally combining unit, a dividing unit 15 for receiving an output of the desired-wave pass filter unit, an orthogonal detection unit 16-19 for receiving an output of the dividing unit, and a filter unit 20 and 21 for receiving an output of the orthogonal detection unit to extract a base band signal therefrom, wherein the receiving path including the summationally combining unit and the following are made into one path to thereby attain miniaturization and low power consumption.

Abstract: A radio communication apparatus is designed for at least first and second radio communication formats which prescribe first and second desired IF pass bandwidths respectively. The first desired IF pass bandwidth is greater than the second desired IF pass bandwidth. The radio communication apparatus includes an IF band-pass filter processing a first IF signal into a second IF signal and having a predetermined pass bandwidth corresponding to the first desired IF pass bandwidth. A demodulator recovers a first baseband signal from the second IF signal generated by the IF band-pass filter. A baseband filter processes the first baseband signal generated by the demodulator into a second baseband signal. The first baseband signal generated by the demodulator is selected as a final output signal when the first IF signal is of the first radio communication format.

Abstract: A received signal obtained from an antenna is subjected to high-frequency amplification. The amplified signal is supplied to a first bandpass filter, which extracts only signals of all the channels of a communications system concerned while filtering out other radio signals. The extracted signals are frequency-converted by using a local oscillation frequency, and only a desired wave is passed by a second bandpass filter. The desired wave is supplied to a sample-and-hold circuit, which performs sampling according to the bandwidth-limiting sampling theorem. A resulting discrete signal is supplied to an I-axis-component and Q-axis-component separating circuits, where the polarity of sample values is inverted for every other clock pulse with respect to each of the I and Q axes to thereby effect Hilbert transform. Resulting two orthogonal components on a phase plane are supplied to a complex coefficient filter.

Abstract: A frequency synthesizer consists of a voltage-controlled oscillator and a frequency division and distribution section. The frequency division and distribution section, which splits an oscillation signal of the voltage-controlled oscillator into a transmission modulation local oscillation signal and a reception second local oscillation signal while frequency-dividing the oscillation signal of the voltage-controlled oscillator, includes two pairs of frequency dividers and two switches. The frequency division numbers of the two pairs of frequency dividers are so set as to accommodate all the combinations of mobile communications systems and the transmission modulation local oscillation signal/reception second local oscillation signal. The two switches are switched in accordance with a mobile communications system for which a mobile transceiver is operating. The two local oscillation signals are input to a quadrature modulator and a quadrature demodulator, respectively.

Abstract: A time division multiple access FDD wireless unit has a first local oscillator 8 for oscillating a first frequency; a second local oscillator 12 for oscillating a second frequency; a n-times multiplier 14 for multiplying the second frequency by n; a m-times multiplier 18 for multiplying the second frequency by m; a converter 6 for transmitting frequency of difference between a reception signal and an output of the first local oscillator 8; a converter 11 for transmitting frequency of sum or difference between an output of the converter 6 and an output of the n-times multiplier 14; modulator 19 for modulating an output of the m-times multiplier 18; a converter 22 for transmitting frequency of sum of an output of the modulator 19 and the output of m-times multiplier 18.

Abstract: A receiving circuit mainly available in a digital modulation type communication system having a plurality of channels, which is capable of reducing power in a receiving system, simplifying the circuit and reducing the power consumption. Upside and downside frequencies corresponding to a central value between channels are separately supplied from a local frequency signal generating circuit 4 to first and second frequency converting circuits 2, 3 so that two output signals are developed with respect to one of a desired wave, upside channel and downside channel. The desired wave present in common in the first and second frequency converting circuits 2, 3 is extracted in a common wave extracting circuit 5, and a frequency offset of .omega.o existing in the output of the common wave extracting circuit 5 is removed a frequency offset circuit 6 and further an unnecessary frequency component is filtered by a filter 8.

Abstract: A multiband mobile unit communication apparatus is disclosed which comprises: an antenna for receiving 1st and 2nd bands of radio wave SIGs including quadrature modulation SIGs; a 1st LO CKT for generating a 1st LO SIG; 1st and 2nd receiving CKTs for generating 1st and 2nd IF SIGs from the 1st and 2nd bands of radio wave SIGs using the 1st LO SIG respectively; a switching CKT responsive to a switching control SIG indicative of 1st and 2nd modes for outputting the 1st IF SIG in the 1st mode and outputting the 2nd IF SIG in the 2nd mode; a 2nd LO CKT for generating 2nd and 3rd LO SIGs in the 1st and 2nd modes respectively; and a quadrature demodulation CKT for demodulating and outputting quadrature SIGs from an output from the switching CKT using the 2nd and third LO SIGs in the 1st and 2nd modes respectively.