Semiconductor circuit having switching element, capacitor, and operational amplifier circuit
AssigneeSemiconductor Energy Laboratory Co., Ltd.
InventorKohei Toyotaka
Life of this patent
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Abstract
A semiconductor circuit which can have stable input output characteristics is provided. Specifically, a semiconductor circuit in which problems caused by the leakage current of a switching element are suppressed is provided. A field-effect transistor in which a wide band gap semiconductor, such as an oxide semiconductor, is used in a semiconductor layer where a channel is formed is used for a switching element included in a switched capacitor circuit. Such a transistor has a small leakage current in an off state. When the transistor is used as a switching element, a semiconductor circuit which has stable input output characteristics and in which problems caused by the leakage current are suppressed can be fabricated.
Claims5
A semiconductor circuit comprising:
- a first switching element and a first capacitor connected in series to each other;
- a second switching element and a second capacitor connected in parallel to each other;
- an operational amplifier circuit;
- and
- a third switching element,
- wherein the third switching element is directly connected to the first switching element and the first capacitor and is directly connected to an output terminal of the operational amplifier circuit,
- wherein an input signal is sampled and a discrete time signal is output, and
- wherein at least one of the first, second, and third switching elements comprises a field-effect transistor whose leakage current in an off state is less than or equal to 1×10−17 A per channel width of 1 μm.
A semiconductor circuit comprising:
- an operational amplifier circuit;
- a first switching element which is electrically connected to a first input terminal of the operational amplifier circuit through a first capacitor;
- a second capacitor which is electrically connected between the first input terminal and a first output terminal of the operational amplifier circuit;
- a second switching element which is electrically connected between the first input terminal and the first output terminal of the operational amplifier circuit;
- a third switching element which is electrically connected to a second input terminal of the operational amplifier circuit through a third capacitor;
- a fourth capacitor which is electrically connected between the second input terminal and a second output terminal of the operational amplifier circuit;
- a fourth switching element which is electrically connected between the second input terminal and the second output terminal of the operational amplifier circuit, and
- a fifth switching element which is directly connected to the first switching element and the first capacitor and is directly connected to the first output terminal of the operational amplifier circuit,
- wherein the second switching element and the second capacitor are connected in parallel to each other, and
- wherein at least one of the first switching element, the second switching element, the third switching element, the fourth switching element, and the fifth switching element comprises a field-effect transistor whose leakage current in an off state is less than or equal to 1×10−17 A per channel width of 1 μm.
Dependencies are inferred from the claim text.