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US 7,095,084 B2Granted
Emitter switching configuration and corresponding integrated structure
AssigneeSTMicroelectronics S.r.l.
InventorCesare Ronsisvalle
Life of this patent
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Abstract
An emitter switching configuration having at least one bipolar transistor and a MOS transistor having a common conduction terminal and a Zener diode inserted between a control terminal of the bipolar transistor and the common conduction terminal. A monolithic structure is also provided that is effective in implementing the emitter switching configuration.
Claims9
A monolithic structure effective to implement an emitter switching configuration, comprising at least one bipolar transistor and a MOS transistor having a common conduction terminal;
- at least one substrate having a first conductivity type whereon a first buried layer having a second conductivity type and a second buried layer having said first conductivity type are formed, said first and second buried layers covered by an epitaxial layer having said first conductivity type, said first buried layer forming, by means of first wells of said second conductivity type a control terminal of said bipolar transistor, and said second buried layer forming said common conduction terminal;
- and second wells of said first conductivity type, adjacent to said first wells of said second conductivity type and in contact with said first wells and with said second buried layer to define a Zener diode parallel to a junction defined by said first and second buried layers with a node of the Zener diode coupled to the control terminal of the bipolar transistor and a cathode coupled to the common conduction terminal.
An integrated emitter switching circuit, comprising:
- a substrate of first conductivity type having a first layer formed thereon of a second conductivity type and a second layer formed on said first layer of the first conductivity type, and an epitaxial layer covering the first and second layers, the epitaxial layer having the first conductivity type;
- first wells of the second conductivity type formed in the epitaxial layer to contact the first layer and second wells of the first conductivity type formed in the epitaxial layer adjacent to and in contact with the first wells and with the second layer to define in combination with the first wells a Zener diode having an anode terminal connected to a base terminal of a bipolar transistor formed in association with the epitaxial layer and a cathode terminal coupled to an emitter terminal of the bipolar transistor and a drain terminal of a MOS transistor formed in association with the epitaxial layer.
Dependencies are inferred from the claim text.