Appeal No. 1997-0601
Application 08/161,878
subject matter.
The disclosed invention relates to an overvoltage
protection circuit. The invention is particularly useful for
protecting devices attached to a standard telephone line.
Overvoltages can occur between the two telephone lines, or
between these lines and ground. Various arrangements of
semiconductive switches are disclosed, such as the two lateral
PNPN switches, to provide for the drain to ground in case of
an overvoltage situation. Additionally, the invention is an
advancement over the art because it integrates all of the
components necessary to create a three-way balanced protective
circuit into a single monolithic integrated circuit. The
invention is further illustrated by the following claim.
Claim 1 is reproduced below as representative of the
invention.
1. An overvoltage protection circuit, comprising:
first and second regions, formed within a substrate
having a first conductivity type, said first and second
regions having a second conductivity type and having the same
area;
third and fourth regions, having the first conductivity
type, formed within said first and second regions,
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