Portable electronic device

摘要

A portable electronic device that can operate even when electric power supplied through contactless charge by electromagnetic induction is low is provided. The portable electronic device includes a reflective liquid crystal display which includes a transistor including an oxide semiconductor, a power source portion which includes a rechargeable battery capable of charge by contactless charge, and a signal processing portion which includes a nonvolatile semiconductor memory device. In the portable electronic device, electric power stored in the rechargeable battery is used in the reflective liquid crystal display and the signal processing portion.

主权项

1. A portable electronic device comprising:
a display portion including a first transistor, a channel region of the first transistor comprising a first oxide semiconductor; a power source portion comprising a rechargeable battery capable of charge by contactless charge; and a signal processing portion comprising a semiconductor memory device, the semiconductor memory device comprising:
a second transistor, a channel region of the second transistor comprising crystalline silicon;a third transistor, a channel region of the third transistor comprising a second oxide semiconductor;a capacitor;a source line;a bit line;a first signal line;a second signal line; anda word line, wherein a gate of the second transistor is electrically connected to one of a source and a drain of the third transistor, a source of the second transistor is electrically connected to the source line, and a drain of the second transistor is electrically connected to the bit line, wherein a gate of the third transistor is electrically connected to the second signal line, the one of the source and the drain of the third transistor is electrically connected to a first electrode of the capacitor, and the other of the source and the drain of the third transistor is electrically connected to the first signal line, and wherein the second oxide semiconductor in the channel region of the third transistor has an off-state current of lower than or equal to 1 aA/μm.