Pacemaker output switch protection
First Claim
1. An output switch serving to electrically connect a source node within a medical device to a destination node within said medical device in response to a control signal, said output switch including:
- a first MOSFET switch formed in a first well region of a first polarity type within a substrate of a second polarity type, said first MOSFET switch having a first source terminal, a first drain terminal, a first gate terminal, and a first well terminal, said source terminal being connected to said source node, said drain terminal being connected to said destination node, said gate terminal being coupled to said control signal, and said first well terminal being connected to said first well region; and
a second MOSFET switch formed in a second well region of the first polarity type having a second source terminal, a second drain terminal, a second gate terminal, and a second well terminal, the second drain terminal being electrically connected to the first source terminal, the second source terminal being electrically connected only to the first and second well terminals, the second well terminal being connected to said second well region and the second gate terminal being electrically coupled to the first drain terminal.
2 Assignments
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Accused Products
Abstract
A protected output switch for an implantable medical device, such as a pacemaker, is disclosed. Through this output switch, a stimulation pulse is delivered from an internal storage element to an output terminal. The output switch includes a first N-channel MOSFET switch having its source terminal connected to the internal storage element and its drain terminal connected to the output terminal. The gate terminal of the N-channel MOSFET switches is connected to approriate logic switching signals. Included as part of the output switch is a second N-channel MOSFET switch having its source terminal connected to the P-well terminal of the first N-channel MOSFET switch, its drain terminal connected to the internal storage element, and its gate terminal connected to the output terminal. This second switch serves to block any potentials, whether internal or external, from being applied to the base of a parasitic NPN bipolar transistor that exists within the output switch. Should such NPN bipolar transistor be turned on, large potentially destructive currents could flow through the output switch.
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Citations
10 Claims
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1. An output switch serving to electrically connect a source node within a medical device to a destination node within said medical device in response to a control signal, said output switch including:
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a first MOSFET switch formed in a first well region of a first polarity type within a substrate of a second polarity type, said first MOSFET switch having a first source terminal, a first drain terminal, a first gate terminal, and a first well terminal, said source terminal being connected to said source node, said drain terminal being connected to said destination node, said gate terminal being coupled to said control signal, and said first well terminal being connected to said first well region; and a second MOSFET switch formed in a second well region of the first polarity type having a second source terminal, a second drain terminal, a second gate terminal, and a second well terminal, the second drain terminal being electrically connected to the first source terminal, the second source terminal being electrically connected only to the first and second well terminals, the second well terminal being connected to said second well region and the second gate terminal being electrically coupled to the first drain terminal. - View Dependent Claims (2, 3)
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4. In an implantable medical device having MOSFET connection means therein for selectively connecting a first node within said medical device to a second node within said medical device, said MOSFET connection means being formed on a semiconductor substrate of a first polarity type and having at least one well region therein of a second polarity type, and wherein source and drain terminals of said MOSFET connection means include regions of said first polarity type within said well region, and further wherein the structure of said MOSFET connection means includes regions of said first polarity type separated by a region of said second polarity type, thereby forming a parasitic bipolar transistor through which potentially large currents can flow, a means for maintaining said parasitic bipolar transistor in an OFF condition, thereby preventing any potentially large currents from flowing through said parasitic bipolar transistor, said means for maintaining said parasitic bipolar transistor in an OFF condition comprising:
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blocking means for preventing any electrical signals from being applied to a base terminal of said parasitic bipolar transistor in response to a blocking signal, said base terminal comprising the region of said second polarity type; and control means for generating said blocking signal and applying it to said base terminal whenever it is desired to maintain said parasitic bipolar transistor in an OFF condition. - View Dependent Claims (5, 6, 7)
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8. Output switch means for use in an implantable medical device for selectively delivering an electrical stimulating pulse to an output terminal, said output switch means causing an electrical potential stored in a storage element of said medical device to be electrically connected to said output terminal for a select period of time in response to a trigger signal, said trigger signal being generated by control logic within said medical device, said output switch means comprising:
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a first semiconductor switch having a first source terminal connected to said storage element, a first destination terminal connected to said output terminal, and a first control terminal coupled to said control logic, said control logic presenting said trigger signal to said first control terminal whenever a stimulation pulse is desired at said output terminal, said trigger signal causing said first source terminal to be electrically connected to said first destination terminal; second semiconductor switch means for switchably connecting a supply potential to said output terminal in response to a turn-on potential, said second semiconductor switch means having a second source terminal coupled to the supply potential, a second destination terminal connected to said output terminal, and a second control terminal, said turn-on potential being applied to said second control terminal; and a third semiconductor switch having a third source terminal connected to the first source terminal of said first semiconductor switch, a third destination terminal connected to the second control terminal of said second semiconductor switch means, and a third control terminal, said third semiconductor switch being controlled so as to block the application of said turn-on potential to the second control terminal of said second semiconductor switch means. - View Dependent Claims (9, 10)
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Specification