On-die termination device

Abstract

An on-die termination includes: a code generator configured to generate a calibration code in response to a voltage of a first node and a reference voltage; a calibration resistor unit connected to the first node, and configured to be turned on and off in response to the calibration code; and a reference resistor unit coupled to the calibration resistor unit, and configured to be turned on and off in response to a control signal.

What is claimed is: 
     
       1. An on-die termination (ODT) device, comprising:
 a code generator configured to generate a calibration code in response to a voltage of a first node and a reference voltage; 
 a calibration resistor unit, including a plurality of calibration resistors, connected to the first node, and configured to be turned on and off in response to the calibration code; and 
 a reference resistor unit coupled, including a reference resistor that is different than the plurality of calibration resistors, connected to the calibration resistor unit, and configured to be turned on or off in response to a control signal, 
 wherein the calibration resistor unit has a plurality of calibration resistors and the reference resistor unit maintains a are connected in parallel connection with the calibration resistor unit during a calibration operation of the plurality of calibration resistors. 
 
     
     
       2. The ODT device as recited in  claim 1 , wherein the control signal is controlled to turn on the reference resistor unit during the calibration operation and turn off the reference resistor unit when the calibration operation is terminated. 
     
     
       3. The ODT device as recited in  claim 1 , wherein the reference resistor unit is provided singularly or in plurality. 
     
     
       4. The ODT device as recited in  claim 1 , wherein the reference resistor unit comprises:
 a basic resistor; 
 a parallel resistor connected to the basic resistor in parallel; and 
 a switch configured to open or close one end of the parallel resistor. 
 
     
     
       5. The ODT device as recited in  claim 1 , wherein the reference resistor unit comprises:
 a basic resistor, 
 a serial resistor connected to the basic resistor in series; and 
 a switch configured to open or close both ends of the serial resistor. 
 
     
     
       6. The ODT device as recited in  claim 1 , wherein the reference resistor unit comprises:
 a basic resistor; 
 a serial resistor connected to the basic resistor in series; 
 a parallel resistor connected to the basic resistor in parallel; and 
 switches configured to open or close both ends of the serial resistor and one end of the parallel resistor, respectively. 
 
     
     
       7. The ODT device as recited in  claim 6 , wherein the switch is provided with a metal option. 
     
     
       8. The ODT device of  claim 6 , wherein the switch comprises:
 a transistor configured to perform a switching operation; and 
 a fuse set configured to store a logic value inputted into the transistor. 
 
     
     
       9. The ODT device as recited in  claim 1 , wherein the code generator comprises:
 a comparator adapted to compare the reference voltage and the voltage of the first node with each other; and 
 a counter adapted to count the calibration code depending on the comparison result of the comparator. 
 
     
     
       10. The ODT device as recited in  claim 1 , wherein the calibration operation is performed such that a total resistance of the calibration resistor unit and the reference resistor unit are equal to a resistance of an external resistor. 
     
     
       11. The ODT device as recited in  claim 1 , wherein the ODT device performs a pull-up termination operation. 
     
     
       12. The ODT device as recited in  claim 1 , wherein the ODT device performs a pull-down termination operation. 
     
     
       13. An on-die termination (ODT) device, comprising:
 a calibration unit connected to an external resistor, including a plurality of calibration resistors, connected in parallel, and a calibration reference resistor that is different than the plurality of calibration resistors to perform a calibration operation and generate a calibration code; and 
 a termination unit, connected with the calibration unit, the termination unit including a plurality of termination resistors, connected in parallel, and a termination reference resistor that is different than the plurality of termination resistors and is connected to an input/output pad, and configured to receive the calibration code to perform impedance matching, 
 wherein each of the calibration reference resistor and the termination units comprises a reference resistor that reference resistor is turned on irrespective independent of the calibration code when the calibration and termination units operate, and 
 wherein each of the calibration unit and the termination units further includes a plurality of resistors connected in parallel and unit is configured to turn on/off in response to the calibration code, and  
 wherein the calibration reference resistor and the termination reference resistor each of the reference resistors maintains a parallel connection with the plurality of calibration resistors and the plurality of termination resistors during a calibration operation of the plurality of calibration resistors. 
 
     
     
       14. The ODT device as recited in  claim 13 , wherein the reference resistor is provided singularly or in plurality. 
     
     
       15. The ODT device as recited in  claim 13 , wherein the calibration and termination units operate as a pull-up resistor. 
     
     
       16. The ODT device as recited in  claim 13 , wherein the calibration and termination units operate as a pull-down resistor. 
     
     
       17. The ODT device as recited in  claim 13 , wherein the reference resistor comprises:
 a basic resistor; 
 a serial resistor connected to the basic resistor in series; 
 a parallel resistor connected to the basic resistor in parallel; and 
 switches configured to open and close both ends of the serial resistor and one end of the parallel resistor, respectively. 
 
     
     
       18. The ODT device as recited in  claim 13 , further comprising:
 an ODT off signal generator adapted to generate an ODT off signal when the external resistor has a high resistance; and 
 an output unit adapted to turn off all the resistors in the calibration unit and the termination unit in response to the ODT off signal. 
 
     
     
       19. The ODT device as recited in  claim 18 , wherein the ODT off signal generator activates the ODT off signal when the calibration code turns off all the resistors under control of the calibration code. 
     
     
       20. The ODT device as recited in  claim 18 , wherein, when the ODT off signal is activated, the output unit turns off all the resistors in the calibration unit and the termination unit by adjusting the calibration code and a control signal controlling the reference resistor. 
     
     
       21. The ODT device as recited in  claim 13 , further comprising:
 an ODT off signal generator configured to activate an ODT off signal when the external resistor has a high resistance; 
 a mode register set (MRS) input unit configured to receive an ODT enable signal set by an MRS to output an MRS signal; 
 a controller configured to output an ODT control signal for turning off or enabling the calibration unit and the termination unit in response to the ODT off signal and the MRS signal; and 
 an output unit configured to control the calibration unit and the termination unit in response to the ODT control signal. 
 
     
     
       22. The ODT device as recited in  claim 21 , wherein the ODT off signal generator activates the ODT off signal when the calibration code turns off all the resistors under control of the calibration code. 
     
     
       23. The ODT device as recited in  claim 21 , wherein the MRS input unit receives the ODT enable signal when an MRS pulse is inputted. 
     
     
       24. The ODT device as recited in  claim 23 , wherein the MRS input unit latches the inputted ODT enable signal to output the MRS signal. 
     
     
       25. The ODT device as recited in  claim 21 , wherein the controller outputs an ODT control signal that turns off all the resistors in the calibration unit and the termination unit when the ODT off signal is activated, and
 the ODT controller outputs an ODT control signal that enables the calibration unit and the termination unit when the ODT enable signal is inputted to the MRS input unit. 
 
     
     
       26. The ODT device as recited in  claim 21 , wherein the output unit turns off all the resistors in the calibration unit and the termination unit by adjusting the calibration code and a control signal controlling the reference resistor when receiving the ODT control signal, which turns off the resistors, from the controller, and
 the output unit controls the calibration unit and the termination unit so as to perform a normal calibration operation when the ODT control signal for enabling the calibration and termination units is inputted. 
 
     
     
       27. A termination circuit for connecting to a calibration circuit, the termination circuit comprising:
 a plurality of resistors connected to a pad and configured to be turned on/off in response to a calibration code; and   a reference resistor that is different than the plurality of resistors connected to the pad and configured to be turned on independent of the calibration code during a termination operation,   wherein the plurality of resistors and the reference resistor are connected to each other in parallel when the plurality of resistors and the reference resistor are turned on, and   wherein the termination reference resistor is connected in parallel with the plurality of resistors during a calibration operation of the calibration circuit.   
     
     
       28. A termination circuit for connecting to a calibration circuit, the termination circuit comprising:
 a plurality of pull-up resistors connected to a pad and configured to be turned on/off in response to a pull-up calibration code;   a pull-up reference resistor connected to the pad and configured to be turned on irrespective of the pull-up calibration code during a pull-up termination operation;   a plurality of pull-down resistors connected to the pad and configured to be turned on/off in response to a pull-down calibration code;   a pull-down reference resistor connected to the pad and configured to be turned on irrespective of the pull-down calibration code during a pull-down termination operation,   wherein the pull-up termination reference resistor and the pull-down reference resistor are connected in parallel with the plurality of pull-up resistors and the plurality of pull-down resistors, respectively, during a calibration operation of the calibration circuit.   
     
     
       29. The termination circuit as recited in claim 28, wherein the plurality of pull-up resistors and the pull-up reference resistor are connected in parallel when the plurality of pull-up resistors and the pull-up reference resistor are turned on, and
 the plurality of pull-down resistors and the pull-down reference resistor are connected in parallel when the plurality of pull-down resistors and the pull-down reference resistor are turned on.