Circuit and method for controlling on-die signal termination
First Claim
Patent Images
1. A control circuit for controlling the impedance of a pad termination comprising:
- a first input for inputting a variable impedance value;
a second input for inputting a fixed impedance value; and
a selector for selecting one of the fixed impedance value and the variable impedance value in response to a selection signal, and for outputting a selected impedance value to a pad termination circuit that provides the impedance of the pad termination in response to the selected impedance value.
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Abstract
A system and method allows for multiple modes of termination, including termination by a fixed value that is preprogrammed, and by a variable value that can, for example, be measured and determined by a self-calibration circuit. Multiple termination values can be achieved within a single device. This configuration is especially applicable to devices that have different loadings for address and data signals, for example in a configuration having a common, shared address bus, and multiple, localized data buses.
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Citations
54 Claims
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1. A control circuit for controlling the impedance of a pad termination comprising:
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a first input for inputting a variable impedance value;
a second input for inputting a fixed impedance value; and
a selector for selecting one of the fixed impedance value and the variable impedance value in response to a selection signal, and for outputting a selected impedance value to a pad termination circuit that provides the impedance of the pad termination in response to the selected impedance value. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18)
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19. A control circuit for controlling the impedance of a pad termination at first and second circuit pads comprising:
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a first circuit for generating a first selected impedance value comprising;
a first input for inputting a variable impedance value;
a second input for inputting a fixed impedance value; and
a first selector, for selecting one of the fixed impedance value and the variable impedance value in response to a selection signal, and for outputting a first selected impedance value to a first pad termination circuit that provides the impedance of the first circuit pad termination in response to the first selected impedance value; and
a second circuit for generating a second selected impedance value comprising;
a third input for inputting the first selected impedance value; and
a second selector, for outputting, in response to the first selected impedance value, a second selected impedance value to a second pad termination circuit that provides the impedance of the second pad termination in response to the second selected impedance value. - View Dependent Claims (20, 21, 22, 23, 24, 25, 26, 27, 28)
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29. A method for controlling the impedance of a pad termination comprising:
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inputting a variable impedance value at a first input;
inputting a fixed impedance value at a second input; and
selecting one of the fixed impedance value and the variable impedance value in response to a selection signal, and outputting a selected impedance value to a pad termination circuit that provides the impedance of the pad termination in response to the selected impedance value. - View Dependent Claims (30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44)
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45. A method for controlling the impedance of a pad termination at first and second circuit pads comprising:
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generating a first selected impedance value comprising;
inputting a variable impedance value at a first input;
inputting a fixed impedance value at a second input; and
selecting one of the fixed impedance value and the variable impedance value in response to a selection signal, and outputting a first selected impedance value to a first pad termination circuit that provides the impedance of the first circuit pad termination in response to the first selected impedance value; and
generating a second selected impedance value comprising;
inputting the first selected impedance value at a third input; and
outputting, in response to the first selected impedance value, a second selected impedance value to a second pad termination circuit that provides the impedance of the second pad termination in response to the second selected impedance value. - View Dependent Claims (46, 47, 48, 49, 50, 51, 52, 53, 54)
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Specification