| 摘要 |
Disclosed is a protection circuit which may be used, for example, in a television receiver to protect circuitry formed within an integrated circuit from damage due to excessively high voltage transients. The protection circuit comprises a PNPN structure forming a silicon controlled rectifier (SCR) and metal-oxide-semiconductor (MOS) transistor integral to the SCR structure. The SCR and the MOS transistors are arranged to form a two terminal protection circuit which is rendered conductive when the potential difference across the two terminals is greater than a predetermined threshold. One terminal of the protection circuit is connected to an input or output signal terminal of the protected circuit, and the other terminal is connected to a reference terminal to which a reference potential such as ground potential is applied. Transient voltages appearing at the integrated circuit terminal greater than the predetermined threshold voltage causes the protection circuit to conduct current, thereby dissipating the energy of the high voltage transient and protecting the integrated circuit from damage. In one embodiment, the gate electrode of the MOS transistor is connected to the reference terminal, and in another to the signal terminal. The latter connection provides a much larger predetermined threshold than the former, and typically considerably in excess of the supply voltage. |
