Renesas Electronics Corporation

Akihiro Toriyama

Kazuki Watanabe

Makoto Toyoshima

Yosuke Tanno

Makoto Shindo

There is included a detection unit for detecting a magnitude of a surplus of a direct current to a source voltage generated by a voltage generation unit generating the source voltage from the direct current obtained by rectifying a signal inputted from an antenna terminal. A data processing unit operating at the source voltage and performing data processing on a transmission/reception signal includes a clock control unit for determining a frequency of a clock signal for the data processing based on the magnitude of the surplus current detected by the detection unit in a state where a frequency of the clock signal is set to a predetermined reference frequency. Since the power consumed by the data processing unit at the time of detecting the surplus of the direct current is determined by the specific reference frequency, the surplus of the direct current can be detected as an absolute surplus.

Contactless communication device, contactless IC card, and mobile information terminal

A semiconductor integrated circuit and an IC card mounted with the same are provided, in which a signal of any one of at least three kinds of reception signals can be received for a short time. An RF signal from an antenna is supplied in parallel to a first and a second demodulator circuit included in a demodulator circuit. The first demodulator circuit demodulates a first reception signal of a first degree of modulation. The second demodulator circuit demodulates a second reception signal having a first communication start signal (SOF), and a third reception signal having a second communication start signal (Preamble). The demodulated output signals of the first and the second demodulator circuit are supplied to a determination circuit. When the demodulation output by the first demodulator circuit is determined, it is determined that the first reception signal is currently received. When the demodulation output of the second reception signal by the second demodulator circuit is determined, it is determined that the second reception signal is currently received. When the demodulation output of the third reception signal by the second demodulator circuit is determined, it is determined that the third reception signal is currently received.

Semiconductor integrated circuit, IC card mounted with the semiconductor integrated circuit, and operation method for the same

In an IC card, even when undershoot or overshoot which occurs upon an amplitude change by communication data is large, the change is accurately detected. A semiconductor device has antenna terminals, a power supply circuit for generating power supply voltage from an AC signal supplied to the antenna terminals, and a receiver circuit for demodulating an information signal superimposed on the AC signal. The receiver circuit includes a rectifier circuit, a filter circuit, a capacitor, an amplifier, a feedback path, a switch circuit, a binarizing circuit, and a control circuit. An output of the amplifier is transmitted to an inverting input terminal thereof, and the switch circuit is controlled by an output of the control circuit. In a predetermined period since level changes of an output of the binarizing circuit, the switch circuit is controlled to an off state by the output of the control circuit.

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Kanagawa, Japan

Akihiro Toriyama