Techniques for reducing leakage current in on-chip impedance termination circuits
DCFirst Claim
1. An integrated circuit comprising a first impedance termination circuit, the first impedance termination circuit comprising:
- a first termination resistor coupled to a first input/output pin on the integrated circuit;
a common mode driver; and
a first transistor coupled between the first termination resistor and the common mode driver, the first transistor blocking current flow through the first termination resistor when the first transistor is OFF;
wherein a body of the first transistor is coupled to a first supply voltage.
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Abstract
Techniques for reducing the leakage currents through on-chip impedance termination circuits are provided. An on-chip impedance termination circuit includes a network of resistors and transistors formed on an integrated circuit. The termination circuit is coupled to one or more IO pins. The transistors can be turned ON and OFF to couple or decouple subsets of the resistors from the IO pins. The bodies of transistors 305-306 are coupled to a supply voltage to cut off leakage current. By pulling the body of these transistors to a supply voltage, the transistor'"'"'s drain/source-to-body diodes turn OFF preventing unwanted leakage current. Also, by moving the source/drain/body node of transistors 301-304 to Node 2, leakage currents through transistors 301-304 are eliminated.
75 Citations
21 Claims
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1. An integrated circuit comprising a first impedance termination circuit, the first impedance termination circuit comprising:
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a first termination resistor coupled to a first input/output pin on the integrated circuit;
a common mode driver; and
a first transistor coupled between the first termination resistor and the common mode driver, the first transistor blocking current flow through the first termination resistor when the first transistor is OFF;
wherein a body of the first transistor is coupled to a first supply voltage. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. A method for providing termination impedance to a first pin using a first termination resistor on an integrated circuit, the method comprising:
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turning OFF a first pass gate to block current through the first termination resistor on the integrated circuit, wherein the first pass gate includes first and second transistors;
driving a voltage on the first pin to high and low supply voltages while the first pass gate is OFF; and
preventing leakage current from flowing through drain/source-to-body diodes of the first and the second transistors while the first pass gate is OFF. - View Dependent Claims (12, 13, 14, 15, 16, 17)
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18. A method for providing termination impedance on an integrated circuit, the method comprising:
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providing a current path through a first on-chip resistor to a pin of the integrated circuit;
blocking current flow through the first on-chip resistor by turning OFF a first transistor; and
preventing source/drain-to-body diodes of the first transistor from becoming forward biased in response to voltage changes on the pin. - View Dependent Claims (19, 20, 21)
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Specification