Matsushita Electric Industrial Co., Ltd.

Matsushita Electronics Corporation

Joji Nakane

Tatsumi Sumi

Atsuo Inoue

Nobuyuki Moriwaki

Taketoshi Matsuura

Yoshitaka Mano

Hiroaki Asada

In a contactless IC card that performs envelope detection on an ASK-modulated carrier wave and demodulates the carrier wave to recover data piggybacked thereon, demodulation is suspended during periods where there is no possibility of a change of a data value (from data 0 to data 1, or from data 1 to data 0) in the digital data piggybacked on the carrier wave. In so doing, incorrect data recovery can be prevented even when noise arises in power supply voltage waveform due to power consumption of an internal memory or the like.

Contactless IC card for preventing incorrect data recovery in demodulation of an amplitude-modulated carrier wave

In a power supply voltage detection circuit using a reference potential generation circuit, as represented by a band gap reference circuit according to a prior art, the correction of dispersion in the detection level cannot be carried out after the completion of diffusion and assembly. Therefore, a power supply voltage detection circuit is provided with a reference potential generation circuit , a divided voltage potential generation circuit and a differential amplification circuit for comparing the divided voltage potential to the reference potential. Furthermore, a ferroelectric memory which stores correction data for correcting the reference potential, a data latch circuit for storing correction data that has been read out, and a microcomputer logic unit for controlling ferroelectric memory as well as data latch circuit are provided. The reference potential is altered according to correction data so that dispersion in the power supply voltage detection level is reduced.

Voltage detection level correction circuit and semiconductor device

A semiconductor integrated circuit which obtains a driving power from a carrier onto which data has been piggybacked, the semiconductor integrated circuit being characterized by demodulating data by correctly discriminating it even when the obtained power supply voltage has become overvoltage, and characterized by effectively using the power supplied by the carrier. The semiconductor integrated circuit includes: a two-voltage rectifier circuit as a power source circuit ; a voltage regulator circuit which exercises a control so that a power with a higher voltage (VDDH) used for demodulating data does not exceed a certain voltage value; a resistor ; and a capacitor . With this construction, the voltage input to a regulator circuit as the reference voltage changes in correspondence to the change in voltage VDDH which is caused by the change in amplitude.

Semiconductor integrated circuit, a contactless information medium having the semiconductor integrated circuit, and a method of driving the semiconductor integrated circuit

Ferroelectric semiconductor memory device

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Nara, Japan

Joji Nakane