Abstract: An amplitude frequency characteristic adjustment circuit 106 is provided downstream of and connected to a distortion generation circuit 105. An amplitude difference between low-frequency-side and high-frequency-side distortion voltages is adjusted by the amplitude frequency characteristic adjustment circuit 106, and then their amplitudes and phases are adjusted by a vector adjustment circuit 107. This configuration makes it possible to suppress simultaneously both of low-frequency-side and high-frequency-side distortion voltages of a distortion generated by a wide-band class-AB power amplifier even if they are different in amplitude and phase.

Abstract: A data converter arranged to enable linear high-efficiency amplification of a signal having a fluctuating envelope. The data converter has a computation circuit, a vector quantizer, and an output terminal. The computation circuit is formed by connecting n (n: a natural number) number of unit circuits each including a vector subtracter having a first input terminal and a second input terminal, and a vector integrator connected to an output side of the vector subtracter. An output at the output terminal and/or an output from each vector integrator are input to the vector subtracter through the second input terminal in the corresponding unit circuit. The vector subtracter outputs data obtained by subtracting a vector input through the second input terminal from a vector input through the first input terminal. The vector quantizer outputs a predetermined value quantized at least with respect to the magnitude of the input vector.

Abstract: A power amplifier of amplifying signals of two frequency bands is reduced in size and improved in efficiency at low output.

Abstract: An amplifier circuit has: a delta-sigma modulator which delta-sigma modulates a signal; and an amplifier which is connected to an output of the delta-sigma modulator. Tn the amplifier circuit, an output voltage of the delta-sigma modulator is controlled in accordance with an output power of the amplifier. When the output power of the amplifier is reduced, the output voltage of the delta-sigma modulator is lowered.

Abstract: In the prior art, it has been difficult to provide a data generator and a data generating method which serve to implement an efficient transmitter, as well as a transmitter utilizing this data generator. The present invention provides a raw data generator that generates, from an inputted signal, an I signal and a Q signal which are orthogonal to each other and an amplitude component of a quadrature signal composed of the I and Q signals, a delta sigma modulator that delta-sigma-modulates the amplitude component, a first multiplier that outputs first data obtained by multiplexing normalized I data obtained by dividing the I signal by the amplitude component, by the delta-sigma-modulated signal, and a second multiplier that outputs second data obtained by multiplexing normalized Q data obtained by dividing the Q signal by the amplitude component, by the delta-sigma-modulated signal.

Abstract: A transmitting circuit device has a first signal source which outputs a first signal that is a binary or multilevel discrete analog signal or a discrete analog signal with a binary or multilevel envelope and that has signal components and quantization noise components; a second signal source which outputs a second signal composed of the quantization noise components; a first amplifier which amplifies the first signal; and a combiner which cancels out the quantization noise components by combining an output of the first amplifier and the second signal.

Abstract: To provide a power amplifier circuit with a smaller circuit scale and with good characteristics over a wide range of load impedance. A configuration includes: a DC/DC converter 2108 which delivers a supply voltage from a battery 2111 to a power amplifier 1302 according to control commands from a control circuit 2109; a directional coupler 2101 which outputs a signal from one terminal 2101a according to signal waves received by an antenna 1306 from a second matching circuit 105 and outputs a signal from another terminal 2101b according to reflected waves received from the antenna 1306; and detectors 2102 and 2103 or the like.

Abstract: An amplitude frequency characteristic adjustment circuit 106 is provided downstream of and connected to a distortion generation circuit 105. An amplitude difference between low-frequency-side and high-frequency-side distortion voltages is adjusted by the amplitude frequency characteristic adjustment circuit 106, and then their amplitudes and phases are adjusted by a vector adjustment circuit 107. This configuration makes it possible to suppress simultaneously both of low-frequency-side and high-frequency-side distortion voltages of a distortion generated by a wide-band class-AB power amplifier even if they are different in amplitude and phase.

Abstract: An amplitude frequency characteristic adjustment circuit 106 is provided downstream of and connected to a distortion generation circuit 105. An amplitude difference between low-frequency-side and high-frequency-side distortion voltages is adjusted by the amplitude frequency characteristic adjustment circuit 106, and then their amplitudes and phases are adjusted by a vector adjustment circuit 107. This configuration makes it possible to suppress simultaneously both of low-frequency-side and high-frequency-side distortion voltages of a distortion generated by a wide-band class-AB power amplifier even if they are different in amplitude and phase.

Abstract: A delay circuit in which amplitude characteristic and delay time characteristic of the output signals do not have any ripple relative to the length of the transmission line is provided. The delay circuit includes a circuit that makes a part of signals distributed into two parts by the power divider (103) to be identical in amplitude and inverse in phase relative to the component of signals outputted from the terminal-a directly to the terminal-c of the circulator (104). By composing with the power combiner (107) both signals are offset each other at the output terminal. As a result, only the signals that are inputted from the input terminal (101) and transmitted through the circulator (104) and the open-ended transmission line (105) are outputted to the output terminal (102).

Abstract: To provide a power amplifier circuit with a smaller circuit scale and with good characteristics over a wide range of load impedance. A configuration includes: a DC/DC converter 2108 which delivers a supply voltage from a battery 2111 to a power amplifier 1302 according to control commands from a control circuit 2109; a directional coupler 2101 which outputs a signal from one terminal 2101a according to signal waves received by an antenna 1306 from a second matching circuit 105 and outputs a signal from another terminal 2101b according to reflected waves received from the antenna 1306; and detectors 2102 and 2103 or the like.

Abstract: An amplitude frequency characteristic adjustment circuit 106 is provided downstream of and connected to a distortion generation circuit 105. An amplitude difference between low-frequency-side and high-frequency-side distortion voltages is adjusted by the amplitude frequency characteristic adjustment circuit 106, and then their amplitudes and phases are adjusted by a vector adjustment circuit 107. This configuration makes it possible to suppress simultaneously both of low-frequency-side and high-frequency-side distortion voltages of a distortion generated by a wide-band class-AB power amplifier even if they are different in amplitude and phase.

Abstract: A multilayer resin wiring board includes a metal core substrate having a first main surface and a second main surface; a plurality of wiring layers located on the first and second main surfaces of the metal core substrate; a plurality of insulating resin layers, each intervening between the metal core substrate and the wiring layers and between the metal core substrate and the wiring layers and between the wiring layers; and a via formed on the wall of a through hole for connection to the metal core substrate extending through the insulating resin layers and the metal core substrate so as to establish electrical conductivity to the metal core substrate. The metal core substrate has a thin portion which is thinner than the remaining portion of the metal core substrate. The through hole for connection to the metal core substrate is formed through the thin portion by laser machining.

Abstract: A predistortion circuit has

Abstract: Disclosed is a transmitter for switching and transmitting signals of plural frequency bands. For example, the signals of two frequency bands are switched and transmitted. For the transmission in a first frequency band, of transistors 104, 105 are turned off, whereby a power amplifying transistor 102 is matched by an input wide band matching circuit 101 and an output main matching circuit 103, so that the high efficiency linear amplification is accomplished. For the transmission in a second frequency band, the transistor 104 is turned on while the transistor 105 is turned off, whereby the power amplifying transistor 102 is matched by a capacitance 108 as well as the input wide band matching circuit 101 and the output main matching circuit 103, so that the high efficiency linear amplification is accomplished. An external switch for switching the matching circuits is thus unnecessary.

Abstract: A method for preparing aromatic compounds including 1,4-difluoropyromellitic dianhydride represented by formula (12): ##STR1## and 1,4-difluoropyromellitic acid represented by formula (15): ##STR2## by dehydrating or hydrolyzing and dehydrating precursors.

Abstract: A perfluorinated polyimide comprising a repeating unit represented by general formula (1): ##STR1## and a perfluorinated poly(amic acid) comprising a repeating unit represented by general formula (6): ##STR2## wherein R.sub.1 is a tetravalent organic group; and R.sub.2 is a divalent organic group, provided that chemical bonds between carbon atoms and monovalent elements contained in R.sub.1 and R.sub.2 are exclusively carbon-to-fluorine bonds; methods for preparing them; and optical material including the perfluorinated polyimide. 1,4-Bis(3,4-dicarboxytrifluorophenoxy)-tetrafluorobenzene dianhydride, 1,4-difluoropyromellitic anhydride, 1,4-bis(3,4-dicarboxytrifluorophenoxy)-tetrafluorobenzene, 1,4-difluoropyromellitic acid, and 1,4-bis(3,4-dicyanotrifluorophenoxy)-tetrafluorobenzene as well as methods preparing them. The perfluorinated polyimide has a thermal stability and has a low optical loss in an optical communication wavelength region (0.8 to 1.7 .mu.m).

Abstract: A perfluorinated aromatic compound represented by general formula (7): ##STR1## wherein R.sub.3 is a tetravalent perfluorinated aromatic group represented by formula (8): ##STR2## wherein (R.sub.4)s are the same, each being a carboxyl group or a cyano group, or two adjacent (R.sub.4)s combine to form a divalent group represented by formula (10): ##STR3## provided that when R.sub.4 is a cyano group, R.sub.3 denotes said tetravalent perfluorinated aromatic group represented by formula (9).

Abstract: In a combining diversity apparatus for a digital multi-valued modulation RF signal, at least first and second receiving antenna units having a space diversity relationship, first and second frequency conversion units for converting the RF signal into first and second IF signals, a combining unit for phasing-combining the first IF signal with the second IF signal, and determination units for determining whether or not the first and second IF signals are interference signals, are provided. When the first or second IF signal is an interference signal, the first or second IF signal is shut off or attenuated by a first switching unit or a second switching unit.

Abstract: A polyimide optical material, composed of a perfluorinated polyimide having a perfluorinated repeating unit represented by general formula (1) ##STR1## wherein R.sub.1 is a tetravalent perfluorinated organic group; and R.sub.2 is a divalent perfluorinated organic group.