1. A bi-directional ESD protection device, comprising
two DIAC devices, each DIAC device comprising
a first and a second p-well formed in an n-well the n-well being formed in a p-substrate and isolated from the substrate by an n-isolation layer, wherein each of the first and second p-well has a p-buried layer formed under it and each p-well includes a p+ region and an n+ region formed in it, the bi-directional ESD protection device further comprising an additional p-region comprises a p+ ring formed in a p-well surrounding each of the DIAC devices.
2. The device of claim 1, wherein the n+ regions in the two p-wells face each other to define a p+, n+, n+, p+ configuration.
3. The device of claim 1, wherein said p+ region is connected to ground.
4. The device of claim 1, wherein for each DIAC, the p+ and n+ regions in the first and second p-wells are connected together.
5. The device of claim 4, wherein the p+ and n+ regions in the first and second p-wells are connected together by means of a first metal layer.
6. The device of claim 4, wherein the n+ and p+ regions in the first p-well of the one DIAC are connected to an input pad.
7. The device of claim 5, wherein the n+ and p+ regions in the first p-well of the one DIAC are connected to an input pad.
8. The device of claim 7, wherein the n+ and p+ regions in the first p-well of the one DIAC are connected to the input pad by means of a second metal layer.
9. The device of claim 6, wherein the n+ and p+ regions in the second p-well of the other DIAC are connected to a ground pad.
10. The device of claim 9, wherein the n+ and p+ regions in the second p-well of the other DIAC are connected to the ground pad by means of a second metal layer.
11. The device of claim 8, wherein the n+ and p+ regions in the second p-well of the other DIAC are connected to a ground pad.
12. The device of claim 11, wherein the n+ and p+ regions in the second p-well of the other DIAC are connected to the ground pad by means of the second metal layer.
13. The device of claim 9, wherein the n+ and p+ regions of the second p-well of the first DIAC are connected to the n+ and p+ regions in the first p-well of the other DIAC.
14. The device of claim 12, wherein the n+ and p+ regions of the second p-well of the first DIAC are connected to the n+ and p+ regions in the first p-well of the other DIAC by means of the second metal layer.
The claims below are in addition to those above.
All refrences to claim(s) which appear below refer to the numbering after this setence.
What is claimed is:
1. A system for providing a plurality of telephone services to multiple customer premises equipment via a pair-gain device, said system comprising:
a combiner circuit coupled to combine a plurality of services for delivery between a source and a user along a common line;
a decombiner circuit coupled to recover said plurality of services from said common line and to provide each recovered service to a corresponding customer premises equipment;
a detector circuit coupled to detect a failure condition in at least one of said combiner circuit and said decombiner circuit; and
a switch responsive to said detected failure and coupled to bypass said at least one of said combiner circuit and said decombiner circuit to provide at least one service of said plurality of services that is determined to be critical between said source and said user.
2. The system of claim 1, wherein said plurality of telephone services includes a digital service and an analog service.
3. The system of claim 2, wherein said analog service comprises a voice band service.
4. The system of claim 1, wherein said plurality of telephone services includes a digital data service and a digital voice service.
5. The system of claim 1, wherein said common line comprises a twisted pair copper telephone line.
6. The system of claim 1, wherein said failure condition includes a loss of power.
7. The system of claim 1, wherein said combiner circuit includes a multiplexer and said decombiner circuit includes a demultiplexer.
8. The system of claim 1, wherein said combiner circuit and said decombiner circuit each include an integrated POTS and ADSL transceiver card.
9. The system of claim 1, wherein said switch includes a relay having normally closed contacts.