Sub-micron high input voltage tolerant input output (I/O) circuit which accommodates large power supply variations
First Claim
1. An system for protecting an integrated circuit from an over voltage, the system comprising:
- a control voltage coupled to the integrated circuit;
a pad voltage from an external voltage source coupled to the integrated circuit at a pad node;
a bias voltage coupled to the integrated circuit at a bias node;
a first diode connected device;
a first switch disposed between the pad node and the bias node;
a second switch disposed between the pad node and a gate of the first switch; and
a third switch disposed between the bias node and the gate of the first switch, wherein, if the control voltage has a value less than a predetermined value, the second switch is turned off and the third switch is turned on to thereby turn on the first switch to provide the bias voltage for the integrated circuit at the bias node, and wherein the pad voltage is applied at the bias node as the bias voltage through the first diode connected device and the first switch.
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Accused Products
Abstract
A method of providing bias voltages for input output connections on low voltage integrated circuits. As integrated circuit voltages drop generally so does the external voltages that those circuits can handle. By placing input and output devices, in series, external voltages can be divided between the devices thereby reducing junction voltages seen by internal devices. By using external voltages as part of a biasing scheme for integrated circuit devices, stress created by the differential between external voltages and internal voltages can be minimized. Additionally device wells can be biased so that they are at a potential that is dependant on the external voltages seen by the low voltage integrated circuit.
42 Citations
25 Claims
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1. An system for protecting an integrated circuit from an over voltage, the system comprising:
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a control voltage coupled to the integrated circuit;
a pad voltage from an external voltage source coupled to the integrated circuit at a pad node;
a bias voltage coupled to the integrated circuit at a bias node;
a first diode connected device;
a first switch disposed between the pad node and the bias node;
a second switch disposed between the pad node and a gate of the first switch; and
a third switch disposed between the bias node and the gate of the first switch, wherein, if the control voltage has a value less than a predetermined value, the second switch is turned off and the third switch is turned on to thereby turn on the first switch to provide the bias voltage for the integrated circuit at the bias node, and wherein the pad voltage is applied at the bias node as the bias voltage through the first diode connected device and the first switch. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
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12. An system for protecting an integrated circuit from an over voltage, the system comprising:
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a control voltage coupled to the integrated circuit;
a pad voltage from an external voltage source coupled to the integrated circuit at a pad node;
a bias voltage coupled to the integrated circuit at a bias node;
a first diode connected device;
a first switch disposed between the pad node and the bias node;
a second switch disposed between the pad node and a gate of the first switch; and
a third switch disposed between the bias node and the gate of the first switch, wherein, if the control voltage has a value less than a predetermined value, the second switch is turned off and the third switch is turned on to thereby turn on the first switch to provide the bias voltage for the integrated circuit at the bias node, and wherein the third switch is coupled to the gate of the first switch through the first diode connected device. - View Dependent Claims (13, 14, 15, 16, 17, 18, 19)
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20. An system for protecting an integrated circuit from an over voltage, the system comprising:
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a control voltage coupled to the integrated circuit;
a pad voltage from an external voltage source coupled to the integrated circuit at a pad node;
a bias voltage coupled to the integrated circuit at a bias node;
a first diode connected device;
a first switch disposed between the pad node and the bias node;
a second switch disposed between the pad node and a gate of the first switch; and
a third switch disposed between the bias node and the gate of the first switch, wherein, if the control voltage has a value less than a predetermined value, the second switch is turned off and the third switch is turned on to thereby turn on the first switch to provide the bias voltage for the integrated circuit at the bias node, and wherein the second switch is turned off by applying the pad voltage to a gate of the second switch through the first diode connected device. - View Dependent Claims (21, 22, 23, 24, 25)
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Specification