Semiconductor integrated circuit device and contactless IC card
First Claim
1. A semiconductor integrated circuit device including a receiver circuit that demodulates an information signal superimposed on an AC signal received through an antenna,said receiver circuit comprising:
- antenna terminals which are connected to said antenna;
a rectifying circuit which rectifies and smoothes said AC signal fed from said antenna to said antenna terminals;
a filter circuit which eliminates a high frequency component from an output signal of said rectifying circuit;
a capacitor;
an operational amplifier with a non-inverting input to which a first reference voltage is input;
a feedback path; and
a binarizing circuit,wherein an output signal of said filter circuit is input via said capacitor to an inverting input of said operational amplifier, andwherein an output signal of said operational amplifier is fed back through said feedback path to the inverting input terminal of said operational amplifier and then input to said binarizing circuit.
3 Assignments
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Accused Products
Abstract
A semiconductor integrated circuit device (IC) and a contactless IC card including a receiver circuit that is able to stably demodulate information signals superimposed on AC signals from an interrogator. The receiver circuit included in the IC is equipped with antenna terminals, a power supply circuit, and a filter circuit. The information signal from which a high frequency component was eliminated through the filter circuit is input via a capacitor to an inverting input terminal of an operational amplifier and a reference voltage is input to a non-inverting input terminal thereof. After the information signal is fed back through a feedback path to the non-inverting input terminal of the operational amplifier, that signal is amplified and the amplified information signal is binarized by a binarizing circuit, thereby data transmitted from the interrogator is demodulated. The contactless IC card comprises an antenna coil and the IC including this receiver circuit.
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Citations
8 Claims
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1. A semiconductor integrated circuit device including a receiver circuit that demodulates an information signal superimposed on an AC signal received through an antenna,
said receiver circuit comprising: -
antenna terminals which are connected to said antenna; a rectifying circuit which rectifies and smoothes said AC signal fed from said antenna to said antenna terminals; a filter circuit which eliminates a high frequency component from an output signal of said rectifying circuit; a capacitor; an operational amplifier with a non-inverting input to which a first reference voltage is input; a feedback path; and a binarizing circuit, wherein an output signal of said filter circuit is input via said capacitor to an inverting input of said operational amplifier, and wherein an output signal of said operational amplifier is fed back through said feedback path to the inverting input terminal of said operational amplifier and then input to said binarizing circuit. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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Specification