Circuit and method for controlling on-die signal termination

Claim 2

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.

Claim 3

The control circuit of claim 1 wherein the fixed impedance value is generated in response to an open or closed state of a fuse, hard-wired state, or bonding state.

Claim 4

The control circuit of claim 1 wherein the fixed impedance value comprises a first fixed impedance value and further comprising a third input for inputting a second fixed impedance value, and wherein the selector selects one of the first fixed impedance value, the second fixed impedance value and the variable impedance value in response to the selection signal, and outputs the selected impedance value to the pad termination circuit.

Claim 5

The control circuit of claim 1 further comprising a fourth input for inputting a deactivation impedance value, and wherein the selector selects one of the fixed impedance value, the variable impedance value, and the deactivation impedance value in response to the selection signal, and outputs the selected impedance value to the pad termination circuit.

Claim 6

The control circuit of claim 4 wherein the pad termination circuit applies the deactivation impedance value by removing the applied impedance.

Claim 7

The control circuit of claim 1 wherein the selector comprises a multiplexer.

Claim 8

The control circuit of claim 1 wherein the variable impedance value is generated by a self-calibration circuit.

Claim 9

The control circuit of claim 7 wherein the self-calibration circuit comprises: a reference node that is coupled to a bonding pad having a reference impedance; a first comparator having a first input coupled to the reference node and a second input coupled to a reference voltage, the comparator comparing the first input and the second input to generate a comparison output; a plurality of impedance loads in parallel between the reference node and a first reference voltage; the plurality of impedance loads being selectively activated in response to the comparison output to provide a combined impedance that substantially matches the reference impedance.

Claim 10

The control circuit of claim 1 wherein the fixed and variable impedance values comprise a plurality of binary bits.

Claim 11

The control circuit of claim 9 wherein the pad termination circuit comprises a bank of resistors, individually selectable according to the binary bits of the fixed or variable impedance values.

Claim 12

The control circuit of claim 10 wherein the plurality of resistors have resistance values that are binary multiples of each other and are connected to a common node that is coupled to a bonding pad, and wherein the impedance of the pad termination is determined by the combined selected resistance values.

Claim 13

The control circuit of claim 1 wherein the selected impedance value comprises a first selected impedance value and further comprising a second selector for receiving the first selected impedance value, and for outputting a second selected impedance value to a second pad termination circuit that provides a second impedance of a second pad termination in response to the second selected impedance value.

Claim 14

The control circuit of claim 12 wherein the second selected impedance value is one of the same as the first selected impedance value, a multiple of the first selected impedance value, a deactivation value, or is independent of the first selected impedance value.

Claim 15

The control circuit of claim 12 wherein one of the first selected impedance value and second selected impedance value is used for termination of one of data and address pads and the other of the first selected impedance value and second selected impedance value is used for termination of the other of data and address pads.

Claim 16

The control circuit of claim 14 wherein at least one of the first and second selected impedance values is further used for termination of command signal pads.

Claim 17

The control circuit of claim 15 wherein the command signal pads comprise pads for at least one of a chip select signal (CSB), a row address signal (RASB), a column address strobe signal (CASB) and a write enable signal (WEB).

Claim 18

The control circuit of claim 1 wherein the selection signal is generated in response to a mode register set (MRS) command used for setting the operation mode of a memory device.

Claim 19

The control circuit of claim 1 wherein the impedance value comprises pull-up and pull-down impedance values.

Claim 20

A control circuit for controlling the impedance of a pad termination at first and second circuit pads comprising: 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.

Claim 21

A control circuit for controlling the impedance of a pad termination at first and second circuit pads comprising: 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.

Claim 22

The control circuit of claim 19 wherein the second selected impedance value is one of the same as the first selected impedance value, a multiple of the first selected impedance value, a deactivation value, or is independent of the first selected impedance value.

Claim 23

The control circuit of claim 19 wherein one of the first selected impedance value and second selected impedance value is used for termination of one of data and address pads and the other of the first selected impedance value and second selected impedance value is used for termination of the other of data and address pads.

Claim 24

The control circuit of claim 21 wherein at least one of the first and second selected impedance values is further used for termination of command signal pads.

Claim 25

The control circuit of claim 22 wherein the command signal pads comprise pads for at least one of a chip select signal (CSB), a row address signal (RASB), a column address strobe signal (CASB) and a write enable signal (WEB).

Claim 26

The control circuit of claim 19 wherein the selection signal is generated in response to a mode register set (MRS) command used for setting the operation mode of a memory device.

Claim 27

The control circuit of claim 19 wherein the second selector further outputs the second selected impedance value in response to a second selection signal.

Claim 28

The control circuit of claim 25 wherein the second selection signal is generated in response to a mode register set (MRS) command used for setting the operation mode of a memory device.

Claim 29

The control circuit of claim 19 wherein the fixed impedance value comprises a first fixed impedance value and wherein the first circuit further comprises a fourth input for inputting a second fixed impedance value, and wherein the selector selects one of the first fixed impedance value, the second fixed impedance value and the variable impedance value in response to the selection signal, and outputs the selected impedance value to the first pad termination circuit.

Claim 30

The control circuit of claim 19 wherein the first circuit further comprises a fifth input for inputting a deactivation impedance value, and wherein the selector selects one of the fixed impedance value, the variable impedance value, and the deactivation impedance value, in response to the selection signal, and outputs the selected impedance value to the first pad termination circuit.

Claim 33

The method of claim 29 wherein the fixed impedance value is generated in response to an open or closed state of a fuse, hard-wired state, or bonding state.

Claim 34

The method of claim 29 wherein the fixed impedance value comprises a first fixed impedance value and further comprising: inputting a second fixed impedance value at a third input; selecting one of the first fixed impedance value, the second fixed impedance value and the variable impedance value in response to the selection signal; and outputting the selected impedance value to the pad termination circuit.

Claim 35

The method of claim 29 further comprising: inputting a deactivation impedance value at a fourth input; selecting one of the fixed impedance value, the variable impedance value, and the deactivation impedance value in response to the selection signal; and outputting the selected impedance value to the pad termination circuit.

Claim 36

The method of claim 32 wherein the pad termination circuit applies the deactivation impedance value by removing the applied impedance.

Claim 37

The method of claim 29 wherein further comprising generating the variable impedance value at a self-calibration circuit.

Claim 38

The method of claim 29 wherein the fixed and variable impedance values comprise a plurality of binary bits.

Claim 39

The method of claim 35 wherein the pad termination circuit comprises a bank of resistors, individually selectable according to the binary bits of the fixed or variable impedance values.

Claim 40

The method of claim 36 wherein the plurality of resistors have resistance values that are binary multiples of each other and are connected to a common node that is coupled to a bonding pad, and wherein the impedance of the pad termination is determined by the combined selected resistance values.

Claim 41

The method of claim 29 wherein the selected impedance value comprises a first selected impedance value and further comprising outputting a second selected impedance value in response to the first selected impedance value to a second pad termination circuit that provides a second impedance of a second pad termination in response to the second selected impedance value.

Claim 42

The method of claim 38 wherein the second selected impedance value is one of the same as the first selected impedance value, a multiple of the first selected impedance value, a deactivation value, or is independent of the first selected impedance value.

Claim 43

The method of claim 38 wherein one of the first selected impedance value and second selected impedance value is used for termination of one of data and address pads and the other of the first selected impedance value and second selected impedance value is used for termination of the other of data and address pads.

Claim 44

The method of claim 40 wherein at least one of the first and second selected impedance values is further used for termination of command signal pads.

Claim 45

The method of claim 41 wherein the command signal pads comprise pads for at least one of a chip select signal (CSB), a row address signal (RASB), a column address strobe signal (CASB) and a write enable signal (WEB).

Claim 46

The method of claim 29 wherein the selection signal is generated in response to a mode register set (MRS) command used for setting the operation mode of a memory device.

Claim 47

The method of claim 29 wherein the impedance value comprises pull-up and pull-down impedance values.

Claim 50

The method of claim 45 wherein the second selected impedance value is one of the same as the first selected impedance value, a multiple of the first selected impedance value, a deactivation value, or is independent of the first selected impedance value.

Claim 51

The method of claim 45 wherein one of the first selected impedance value and second selected impedance value is used for termination of one of data and address pads and the other of the first selected impedance value and second selected impedance value is used for termination of the other of data and address pads.

Claim 52

The method of claim 47 wherein at least one of the first and second selected impedance values is further used for termination of command signal pads.

Claim 53

The method of claim 48 wherein the command signal pads comprise pads for at least one of a chip select signal (CSB), a row address signal (RASB), a column address strobe signal (CASB) and a write enable signal (WEB).

Claim 54

The method of claim 45 wherein the selection signal is generated in response to a mode register set (MRS) command used for setting the operation mode of a memory device.

Claim 55

The method of claim 45 wherein further comprising outputting the second selected impedance value in response to a second selection signal.

Claim 56

The method of claim 51 wherein the second selection signal is generated in response to a mode register set (MRS) command used for setting the operation mode of a memory device.

Claim 57

The method of claim 45 wherein the fixed impedance value comprises a first fixed impedance value and wherein generating a first selected impedance value comprises: inputting a second fixed impedance value at a fourth input; selecting one of the first fixed impedance value, the second fixed impedance value and the variable impedance value in response to the selection signal; and outputting the selected impedance value to the first pad termination circuit.

Claim 58

The method of claim 45 wherein generating a first selected impedance value further comprises: inputting a deactivation impedance value at a fifth input, selecting one of the fixed impedance value, the variable impedance value, and the deactivation impedance value in response to the selection signal; and outputting the selected impedance value to the first pad termination circuit.