Semiconductor device

• US 20080230821A1
• Filed: 03/07/2008
• Published: 09/25/2008
• Est. Priority Date: 03/22/2007
• Status: Active Grant

• Current Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Original Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Inventors: Shionoiri, Yutaka
• Granted Patent: US 8,331,873 B2
• Time in Patent Office: Days
• US Class Current: 257/296
• CPC Class Codes: G06K 19/0701 at least one of the integrated circuit chips comprising an arrangement for power management
• CPC Class Codes: G06K 19/0715 the arrangement including means to regulate power transfer to the integrated circuit
• CPC Class Codes: G06K 19/0723 the record carrier comprising an arrangement for non-contact communication, e.g. wireless communication circuits on transponder cards, non-contact smart cards or RFIDs

Abstract

In a semiconductor device which can perform data communication through wireless communication, to suppress transmission and the like of an AC signal, the semiconductor device includes an input circuit to which a radio signal is input, a first circuit, which generates a constant voltage, such as a constant voltage circuit or a limiter circuit, a second circuit to which the generated constant voltage is input and which can change impedance of the semiconductor device, and a filter provided between the first circuit and the second circuit. Transmission of an AC signal is suppressed by the filter, and malfunctions or operation defects such as complete inoperative due to variation in the constant voltage is prevented.

Claims

1. A semiconductor device, comprising:

an input circuit generating a DC voltage from an AC signal;

a circuit generating a constant voltage using the DC voltage;

a circuit portion supplied with the constant voltage;

a filter; and

a feedback circuit in which impedance varies in accordance with the constant voltage input through the filter,

wherein the filter is provided between the circuit portion and the feedback circuit.

2. The semiconductor device according to claim 1,

wherein the filter includes a first resistance element and a capacitor element,

wherein the feedback circuit includes a second resistance element and a transistor,

wherein an output of the circuit generating the constant voltage is connected to one terminal of the first resistance element, one terminal of the capacitor element and an input of the circuit portion,

wherein the other terminal of the first resistance element is connected to a gate of the transistor, and

wherein one of a source and a drain of the transistor is connected to one terminal of the second resistance element.

3. The semiconductor device according to claim 1,

wherein the filter includes an inductor element and a capacitor element,

wherein the feedback circuit includes a resistance element and a transistor,

wherein an output of the circuit generating the constant voltage is connected to one terminal of the inductor element, one terminal of the capacitor element and an input of the circuit portion,

wherein the other terminal of the inductor element is connected to a gate of the transistor, and

wherein one of a source and a drain of the transistor is connected to one terminal of the resistance element.

4. A semiconductor device, comprising:

an antenna, wherein the antenna is capable of data communication through wireless communication;

an input circuit generating a DC voltage from an AC signal sent from the antenna;

a circuit generating a constant voltage using the DC voltage;

a circuit portion supplied with the constant voltage;

a filter; and

a feedback circuit in which impedance varies in accordance with the constant voltage input through the filter,

wherein the filter is provided between the circuit portion and the feedback circuit.

5. The semiconductor device according to claim 4,

wherein the filter includes a first resistance element and a capacitor element,

wherein the feedback circuit includes a second resistance element and a transistor,

wherein an output of the circuit generating the constant voltage is connected to one terminal of the first resistance element, one terminal of the capacitor element and an input of the circuit portion,

wherein the other terminal of the first resistance element is connected to a gate of the transistor,

wherein one of a source and a drain of the transistor is connected to one terminal of the second resistance element, and

wherein the other of the source and the drain of the transistor is connected to one terminal of the antenna and the other terminal of the capacitor element.

6. The semiconductor device according to claim 4,

wherein the filter includes an inductor element and a capacitor element,

wherein the feedback circuit includes a resistance element and a transistor,

wherein an output of the circuit generating the constant voltage is connected to one terminal of the inductor element and one terminal of the capacitor element and an input of the circuit portion,

wherein the other terminal of the inductor element is connected to a gate of the transistor,

wherein one of a source and a drain of the transistor is connected to one terminal of the resistance element, and

wherein the other of the source and the drain of the transistor is connected to one terminal of the antenna and the other terminal of the capacitor element. element is connected to one terminal of the antenna.