Constant gate drive MOS analog switch
First Claim
1. An analog switch coupled to an input terminal and an output terminal, comprising:
- a first device including a source coupled to the input terminal, a drain coupled to the output terminal, and a gate;
a second device including a source coupled to the input terminal, a drain, and a gate;
a third device including a source coupled to the drain of the second device, a drain coupled to the output terminal, and a gate coupled to the gates of the first and second devices; and
a level shifter including an input coupled to the drain of the second device and an output coupled to the gates of the first, second, and third device, the level shifter providing an approximately constant gate-to-source voltage relative to source-to-drain voltage of the first device.
1 Assignment
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Accused Products
Abstract
A constant gate drive metal-oxide semiconductor ("MOS") analog switch. In one embodiment, the analog switch includes first, second, and third devices, and a level shifter. The first device includes a source coupled to an input terminal, a drain coupled to an output terminal, and a gate. The second device includes a source coupled to the input terminal, a drain, and a gate. The third device includes a source coupled to the drain of the second device, a drain coupled to the output terminal, and a gate. The level shifter includes an input coupled to the drain of the second device and an output coupled to the gates of the first, second, and third devices. The level shifter provides a constant gate drive to the first device, regardless of a signal on the input terminal, resulting in a constant on-resistance of the analog switch. In addition, a constant linearity of on-resistance is achieved by keeping the gate voltage constant with respect to the mid-point of the source and drain voltages.
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Citations
23 Claims
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1. An analog switch coupled to an input terminal and an output terminal, comprising:
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a first device including a source coupled to the input terminal, a drain coupled to the output terminal, and a gate; a second device including a source coupled to the input terminal, a drain, and a gate; a third device including a source coupled to the drain of the second device, a drain coupled to the output terminal, and a gate coupled to the gates of the first and second devices; and a level shifter including an input coupled to the drain of the second device and an output coupled to the gates of the first, second, and third device, the level shifter providing an approximately constant gate-to-source voltage relative to source-to-drain voltage of the first device. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. An analog switch coupled to an input terminal and an output terminal, comprising:
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a first device including a source coupled to the input terminal, a drain coupled to the output terminal, and a gate; a circuit coupled to the input terminal, the output terminal, and the gate of the first device; and a level shifter including an input coupled to the circuit and an output coupled to the gate of the first device and the circuit, the level shifter providing an approximately constant gate-to-source voltage relative to source-to-drain voltage of the first device. - View Dependent Claims (12, 13, 14, 15, 16, 17, 18, 19, 20)
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21. An analog switch coupled to an input terminal and an output terminal, comprising:
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a first device including a source coupled to the input terminal, a drain coupled to the output terminal, and a gate; a second device including a first node coupled to the input terminal, a second node, and a gate; a third device including a first node coupled to the second node of the second device, a second node coupled to the output terminal, and a gate; and a level shifter including an input coupled to the second node of the second device and an output coupled to the gates of the first, second, and third device, the level shifter providing an approximately constant gate-to-source voltage relative to source-to-drain voltage of the first device. - View Dependent Claims (22, 23)
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Specification