Abstract: A semiconductor integrated circuit includes a functional circuit and a power source voltage generating circuit used for operating the functional circuit. In the power source voltage generating circuit, output stage transistors are driven by comparing a plurality of reference voltages produced by a plurality of resistors connected in series to one another with output voltages of a plurality of differential amplifiers connected in parallel to one another and varying gate voltages.

Abstract: The semiconductor memory device formed on a semiconductor substrate includes: a memory cell array having a plurality of memory cells formed at intersections between a plurality of word lines and a plurality of bit line pairs; a plurality of sense amplifiers each formed to correspond to each of the plurality of bit line pairs for amplifying a potential difference read on the bit line pair; and a low-level potential generation section for generating a low-level potential out of high-level and low-level potentials to be applied to the memory cells, the bit line pairs, and the sense amplifiers.

Abstract: A portable communication system includes a first metal housing for containing a high frequency circuit unit such as a transmitting circuit and a receiving circuit, a second metal housing for containing a low frequency circuit unit such as a control circuit, and also an antenna mounted on the first metal housing. An antenna apparatus for this portable communication system is arranged by the above-explained antenna, first and second metal housings, and also a control element for controlling distribution of high frequency currents flowing through the first and second metal housings. An antenna radiation pattern of this antenna apparatus can be optimized by controlling an impedance of the control element.

Abstract: A data transmission system includes a data carrier which has a memory for storing therein data including an identification code and which is attached to an object and a main apparatus having a microwave oscillator so as to conduct communications with the data carrier by use of a microwave, thereby writing data in or reading data from the memory of the data carrier.The main apparatus transmits a microwave modulated by a command or data and thereafter transmits a nonmodulated carrier for a predetermined period of time. On receiving a command, the data carrier executes a read/write operation on the memory and then generates a response. The data carrier receives the nonmodulated carrier sent from the main apparatus so as to conduct a modulation of quadrature phase-shift keying thereon by use of response data, thereby reflectively transmitting the modulated carrier with a plane of polarization shifted from a plane of polarization of the received wave by 90.degree..