| 摘要 |
A constant gate drive metal-oxide semiconductor ("MOS") analog switch is described. 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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