Semiconductor device with high voltage protection
First Claim
1. A semiconductor device comprising:
- a plurality of pads for performing signal inputting and outputting, said pads comprising an input pad and an output pad;
an analog switch, which is provided with P type and N type MOS transistors for transmitting signals among said pads, said N type MOS transistor comprising first and second N type diffusion layers separated by a gate of said N type MOS transistor, said first N type diffusion layer connected to said input pad and said second N type diffusion layer connected to said output pad; and
a protective circuit, which is provided with P type and N type protective MOS transistors for protecting said analog switch,wherein said analog switch is further provided with an N type dummy transistor, said N type dummy transistor being formed by using said first N type diffusion layer as a drain and connecting a gate and a source to a ground potential.
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Accused Products
Abstract
The object of the present invention is to provide a semiconductor device, which has a high protective capability against an excessive voltage applied from the outside. The device is provided, in its analog switch 30, with a P type dummy transistor 11 whose drain terminal is connected to a P type diffusion layer in the outside of a P type transfer gate 4 and whose gate and source terminals are connected to a power supply potential, and an N type dummy transistor 12 whose drain terminal is connected to an N type diffusion layer in the outside of an N type transfer gate 5 and whose gate and source terminals are connected to a ground potential, and when an excessive voltage is applied from the outside, an excessive current is made to flow through the P type and N type dummy transistors 11 and 12 to the power supply potential or the ground potential.
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Citations
11 Claims
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1. A semiconductor device comprising:
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a plurality of pads for performing signal inputting and outputting, said pads comprising an input pad and an output pad; an analog switch, which is provided with P type and N type MOS transistors for transmitting signals among said pads, said N type MOS transistor comprising first and second N type diffusion layers separated by a gate of said N type MOS transistor, said first N type diffusion layer connected to said input pad and said second N type diffusion layer connected to said output pad; and a protective circuit, which is provided with P type and N type protective MOS transistors for protecting said analog switch, wherein said analog switch is further provided with an N type dummy transistor, said N type dummy transistor being formed by using said first N type diffusion layer as a drain and connecting a gate and a source to a ground potential. - View Dependent Claims (2, 3, 5)
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4. A semiconductor device comprising:
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a plurality of pads for performing signal inputting and outputting, said pads comprising an input pad and an output pad; an analog switch, which is provided with P type and N type MOS transistors for transmitting signals among said pads, said P type MOS transistor comprising first and second P type diffusion layers separated by a gate of said P type MOS transistor, said first P type diffusion layer connected to said input pad and said second P type diffusion layer connected to said output pad; and a protective circuit, which is provided with P type and N type protective MOS transistors for protecting said analog switch, wherein said analog switch is further provided with a P type dummy transistor, said P type dummy transistor being formed by using said first P type diffusion layer as a drain and connecting a gate and a source to a power supply potential.
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6. A semiconductor device comprising:
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a plurality of pads for performing signal inputting and outputting, said pads comprising input pad and an output pad; an output circuit, which is provided with first and second P type MOS transistors connected to each other in series between a power supply potential and said output pad, said first P type MOS transistor comprising first and second P type diffusion layers separated by a gate of said first P type MOS transistor, said first P type diffusion layer connected to said output sad; and a protective circuit, which is provided with P type and N type protective MOS transistors for protecting said output circuit, wherein said output circuit is further provided with a P type dummy transistor, said P type dummy transistor being formed by using said first P type diffusion layer as a drain and connecting a gate and a source to said power supply potential. - View Dependent Claims (7, 8)
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9. A semiconductor device comprising:
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a plurality of pads for performing signal inputting and outputting, said pads comprising an input pad and an output pad; an output circuit, which is provided with first and second N type MOS transistors connected to each other in series between a ground potential and said output pad, said first N type MOS transistor comprising first and second N type diffusion layers separated by a gate of said first N type MOS transistor, said first N type diffusion layer being connected to said output pad; and a protective circuit, which is provided with P type and N type protective MOS transistors for protecting said output circuit, wherein said output circuit is further provided with an N type dummy transistor, said N type dummy transistor being formed by using said first N type diffusion layer as a drain and connecting a gate and a source to said ground potential. - View Dependent Claims (10, 11)
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Specification