Protection circuit and a circuit for a semiconductor-on-insulator device

Claim 2

A protection circuit comprising: a pad node; a first supply node that is coupled to receive a first potential; a first transistor having a first current electrode, a channel, and a second current electrode, wherein: the first current electrode of the first transistor is electrically connected to both the first supply node and the channel; the second current electrode of the first transistor is electrically connected to the pad node; and a pn diode is formed at a junction between the channel and second current electrode of the first transistor; a second transistor having a first current electrode, a second current electrode, and a channel which electrically floats by remaining unconnected with either the first or second current electrodes thereof, wherein: the first current electrode of the second transistor is electrically connected to the first supply node; and the second current electrode of the second transistor is electrically connected to the pad node; the second transistor functioning as a primary current path for current flow from the pad node to the first supply node; a second supply node that is coupled to receive a second potential that is higher than the first potential; and a rail clamp having a first terminal and a second terminal, wherein: the first terminal of the rail clamp is electrically connected to the first supply node; and the second terminal of the rail clamp is electrically connected to the second supply node.

Claim 3

The protection circuit of claim 1, wherein the rail clamp is a zener diode.

Claim 4

The protection circuit of claim 1, wherein the second transistor has a control electrode that is electrically connected to the first current electrode of the second transistor.

Claim 5

The protection circuit of claim 1, further comprising a first diode having a positive terminal and a negative terminal, wherein: the positive terminal of the first diode is coupled to the pad node; and the negative terminal of the first diode is coupled to the second supply node.

Claim 6

The protection circuit of claim 4, further comprising a resistor, a second diode, and a third diode, wherein: the resistor has a first terminal and a second terminal; each of the second diode and the third diode has a positive terminal and a negative terminal; the first terminal of the resistor is electrically connected to the pad node; the positive terminal of the second diode is electrically connected to the first supply node; the negative terminal of the third diode is electrically connected to the second supply node; and the second terminal of the resistor, the negative terminal of the second diode, and the positive terminal of the third diode are electrically connected to one another.

Claim 7

The protection circuit of claim 1, further comprising a third transistor having a first current electrode and a second current electrode, wherein: the first current electrode of the third transistor is electrically connected to the second supply node; and the second current electrode of the third transistor is electrically connected to the pad node.

Claim 8

The protection circuit of claim 6, further comprising a first diode and a second diode, wherein: each of the first diode and the second diode has a positive terminal and a negative terminal; the positive terminal of the first diode is electrically connected to the first supply node; the negative terminal of the first diode is electrically connected to a control electrode of the first transistor; the positive terminal of the second diode is electrically connected to a control electrode of the third transistor; and the negative terminal of the second diode is electrically connected to the second supply node.

Claim 9

The protection circuit of claim 1, wherein: the protection circuit is electrically connected to a pad; and the second current electrodes of the first and second transistors and the pad are at approximately a same potential.

Claim 10

The protection circuit of claim 1, wherein the protection circuit is part of a semiconductor-on-insulator device.

Claim 11

A circuit for a semiconductor-on-insulator device comprising: a pad; and a protection circuit including: a first supply node that is coupled to receive a first potential; a first transistor having a first current electrode and a second current electrode, wherein: the first current electrode of the first transistor is connected to the first supply node; and the second current electrode of the first transistor is connected to the pad; and the first transistor is a body-tied transistor; a second transistor having a first current electrode, a second current electrode, and a control electrode, wherein: the first current electrode and the control electrode of the second transistor are connected to the first supply node; and the second current electrode of the second transistor is connected to the pad, the first transistor being a body-tied transistor having an increased voltage at which parasitic bipolar action occurs between the first and second current electrodes thereof and being electrically connected in parallel with the second transistor to make a primary current path between the pad and first supply node be through the second transistor rather than the first transistor; a second supply node that is coupled to receive a second potential that is higher than the first potential; and a first zener diode having a positive terminal and a negative terminal, wherein: the positive terminal of the first zener diode is connected to the first supply node; and the negative terminal of the first zener diode is connected to the second supply node.

Claim 12

A circuit for a semiconductor-on-insulator device comprising: a pad; and a protection circuit including: a first supply node that is coupled to receive a first potential; a first transistor having a first current electrode and a second current electrode, wherein: the first current electrode of the first transistor is connected to the first supply node; and the second current electrode of the first transistor is connected to the pad; and the first transistor is a body-tied transistor; a second transistor having a first current electrode, a second current electrode, and a control electrode, wherein: the first current electrode and the control electrode of the second transistor are connected to the first supply node; and the second current electrode of the second transistor is connected to the pad, the first transistor being a body-tied transistor having an increased voltage at which parasitic bipolar action occurs between the first and second current electrodes thereof and being electrically connected in parallel with the second transistor to make a primary current path between the pad and first supply node be through the second transistor rather than the first transistor; a second supply node that is coupled to receive a second potential that is higher than the first potential; and a first zener diode having a positive terminal and a negative terminal, wherein: the positive terminal of the first zener diode is connected to the first supply node; and the negative terminal of the first zener diode is connected to the second supply node.

Claim 13

The circuit of claim 10, wherein the protection circuit further comprises a second zener diode having a positive terminal and a negative terminal, wherein: the positive terminal of the second zener diode is connected to the pad; and the negative terminal of the second zener diode is connected to the second supply node.

Claim 14

The circuit of claim 11, wherein the protection circuit further comprises a resistor, a third zener diode, and a fourth zener diode, wherein: the resistor has a first terminal and a second terminal; each of the third zener diode and the fourth zener diode has a positive terminal and a negative terminal; the first terminal of the resistor is connected to the pad; the positive terminal of the third zener diode is connected to the first supply node; the negative-terminal of the fourth zener diode is connected to the second supply node; and the second terminal of the resistor, the negative terminal of the third zener diode, the positive terminal of the fourth zener diode are connected to one another.

Claim 15

The circuit of claim 12, further comprising a third transistor and a fourth transistor, wherein: each of the third transistor and the fourth transistor includes a control electrode, a first current electrode and a second current electrode; the first current electrode of the third transistor is connected to the first supply node; the first current electrode of the fourth transistor is connected to the second supply node; the second current electrodes of the third and fourth transistors are connected to each other; and the control electrodes of the third and fourth transistors and the second terminal of the resistor are connected to one another.

Claim 16

The circuit of claim 13, further comprising a fifth transistor having a first current electrode and a second current electrode, wherein: the first current electrode of the fifth transistor is connected to the second supply node; and the second current electrode of the fifth transistor is connected to the pad.

Claim 17

The circuit of claim 14, further comprising a fifth zener diode and a sixth zener diode, wherein: each of the fifth zener diode and the sixth zener diode includes a positive terminal and a negative terminal; the positive terminal of the fifth zener diode is connected to the first supply node; the negative-terminal of the fifth zener diode is connected to a control electrode of the first transistor; the positive terminal of the sixth zener diode is connected to a control electrode of the fifth transistor; and the negative terminal of the sixth zener diode is connected to the second supply node.

Claim 18

The circuit of claim 15, wherein: each of the third and fourth transistors is part of an input buffer circuit; the second current electrodes of the third and fourth transistors are connected to an input circuit; and each of the first and fifth transistors has a control electrode and is part of an output buffer circuit; the control electrodes of the first and fifth transistors are connected to an output circuit; and the pad is an input/output pad.

Claim 19

The circuit of claim 13, wherein: each of the third and fourth transistors is part of an input buffer circuit; the second current electrodes of the third and fourth transistors are connected to a first input circuit; and the pad is an input pad.

Claim 20

The circuit of claim 11, wherein the protection circuit further comprises a third transistor having a first current electrode and a second current electrode, wherein: the first current electrode of the third transistor is connected to the second supply node; and the second current electrode of the third transistor is connected to the pad.

Claim 21

The circuit of claim 18, wherein: each of the first and third transistors has a control electrode and is part of an output buffer circuit; the control electrodes of the first and third transistors are connected to an output circuit; and the pad is an output pad.

Claim 22

The circuit of claim 18, further comprising a third zener diode and a fourth zener diode, wherein: each of the third and fourth zener diodes has a positive terminal and a negative terminal; each of the first and third transistors has a control electrode; the positive terminal of the third zener diode is connected to the first supply node; the negative terminal of the third zener diode is connected to the control electrode of the first transistor; the positive terminal of the fourth zener diode is connected to the control electrode of the third transistor; and the negative terminal of the fourth zener diode is connected to the second supply node.

Claim 23

The circuit of claim 10, wherein the pad and the second current electrodes of the first and second transistors are at approximately a same potential.

Claim 24

A protection circuit comprising: a first pad electrically connected to a first node; a first transistor having a first current electrode, a channel, and a second current electrode, the first current electrode of the first transistor is electrically connected to both a second node and the channel; the second current electrode is electrically connected to the first node; and a first body tie diode is formed at a junction between the channel and second current electrode of the first transistor; a second transistor having a first current electrode and a second current electrode, wherein: the first current electrode of the second transistor is electrically connected to the second node; and the second current electrode of the second transistor is electrically connected to the first node; a first rail clamp having a first terminal and a second terminal, wherein: the first terminal of the first rail clamp is electrically connected to the second node; and the second terminal of the first rail clamp is electrically connected to a third node; a second pad being electrically connected to a fourth node; a third transistor having a first current electrode and a second current electrode, wherein: the first current electrode of the third transistor is electrically connected to the second node; and the second current electrode of the third transistor is electrically connected to the fourth node; a second body tie diode is formed at a junction between the channel and second current elect-rode of the third transistor; and a fourth transistor having a first current electrode and a second current electrode, wherein: the first current electrode of the fourth transistor is electrically connected to the second node; and the second current electrode of the fourth transistor is electrically connected to the fourth node.

Claim 25

A protection circuit comprising: a first pad electrically connected to a first node; a first transistor having a first current electrode, a channel, and a second current electrode, the first current electrode of the first transistor is electrically connected to both a second node and the channel; the second current electrode is electrically connected to the first node; and a first body tie diode is formed at a junction between the channel and second current electrode of the first transistor; a second transistor having a first current electrode and a second current electrode, wherein: the first current electrode of the second transistor is electrically connected to the second node; and the second current electrode of the second transistor is electrically connected to the first node; a first rail clamp having a first terminal and a second terminal, wherein: the first terminal of the first rail clamp is electrically connected to the second node; and the second terminal of the first rail clamp is electrically connected to a third node; a second pad being electrically connected to a fourth node; a third transistor having a first current electrode and a second current electrode, wherein: the first current electrode of the third transistor is electrically connected to the second node; and the second current electrode of the third transistor is electrically connected to the fourth node; a second body tie diode is formed at a junction between the channel and second current elect-rode of the third transistor; and a fourth transistor having a first current electrode and a second current electrode, wherein: the first current electrode of the fourth transistor is electrically connected to the second node; and the second current electrode of the fourth transistor is electrically connected to the fourth node.

Claim 26

The protection circuit of claim 22, wherein the first rail clamp is a zener diode.

Claim 27

The protection circuit of claim 22, further comprising a second rail clamp having a first terminal and a second terminal, wherein: the first terminal of the second rail clamp is coupled to the second node; and the second terminal of the second rail clamp is coupled to the third node.

Claim 28

The protection circuit of claim 24, wherein the first and second rail clamps are zener diodes.

Claim 29

The protection circuit of claim 22, wherein: the second transistor has a control electrode that is electrically connected to the first current electrode of the second transistor; and the fourth transistor has a control electrode that is electrically connected to the first current electrode of the fourth transistor.

Claim 30

The protection circuit of claim 22, further comprising a first diode and a second diode, wherein: each of the first and second diodes has a positive terminal and a negative terminal; the positive terminal of the first diode is coupled to the first node; the negative terminal of the first diode is coupled to the third node; the positive terminal of the second diode is coupled to the fourth node; and the negative terminal of the second diode is coupled to the third node.

Claim 31

The protection circuit of claim 27, wherein: the second current electrodes of the first and second transistors, and the positive terminal of the first diode are electrically connected to the first node; the first current electrodes of the first, second, third, and fourth transistors and the first terminal of the first rail clamp are electrically connected to the second node; the second terminal of the first rail clamp and the negative terminals of the first and second diodes are electrically connected to the third node; and the second current electrodes of the third and fourth transistors and the positive terminal of the second diode are electrically connected to the fourth node.

Claim 32

The protection circuit of claim 22, wherein the protection circuit is part of a semiconductor-on-insulator device.