Calibration device and memory system having the same
A calibration device for use in a memory system includes a bias circuit providing bias current, and a calibration unit generating a control signal for calibration. The bias circuit includes an internal resistor and measures a second bias current generated by mirroring a first bias current through the internal resistor, and adjusts the second bias current to generate the second bias current in a predetermined range as a third bias current. The calibration unit generates the control signal based on a comparison result between a reference voltage and a voltage generated based on the third bias current through an adjustable resistor.
1. A calibration device comprising:
a bias circuit configured to provide bias current; and
a calibration unit configured to generate a control signal for calibration,
wherein the bias circuit includes an internal resistor and is configured to measure a second bias current generated by mirroring a first bias current through the internal resistor, and adjust the second bias current to generate a third bias current in a predetermined range, an eFuse is configured to store a DAC code corresponding to the third bias current, an external device connection unit configured to provide an input DAC code via a serial port and sense the second bias current via a common test pin in a manufacturing phase of the calibration device; and
wherein the calibration unit is configured to generate the control signal based on a comparison result between a reference voltage and a voltage generated based on the third bias current through an adjustable resistor.
2. The device of claim 1 , wherein the bias circuit is configured to
measure the second bias current, and adjust the second bias current to generate the third bias current, during the manufacturing phase of the calibration device, and
output the third bias current to the calibration unit during a normal operation of the calibration device.
3. The device of claim 2 , wherein the bias circuit comprises:
a current generation block including the internal resistor, configured to generate the first bias current flow through the internal resistor; and
a current digital-to-analog converter (DAC) configured to receive an input DAC code, and output the second bias current and the third bias current based on the DAC code and the first bias current.
4. The device of claim 3 , wherein during the manufacturing phase, the current DAC is configured to receive the input DAC code from an external device, and output the second bias current to the external device, and
during the normal operation, the current DAC is configured to receive the input DAC code from the eFuse, and output the third bias current to the calibration unit.
5. The device of claim 4 , further comprising:
a multiplexer coupled between the current DAC and one of the external device and the eFuse, configured to provide the current DAC with the input DAC code from one of the external device and the eFuse; and
a demultiplexer coupled between the current DAC and one of the external device and the calibration unit, configured to output the second bias current to the external device and output the third bias current to the calibration unit.
6. The device of claim 3 , wherein the current generation block comprises:
a reference transistor coupled between the current DAC and the internal resistor in series;
a bandgap voltage generator configured to generate a bandgap voltage; and
a comparator configured to compare the bandgap voltage with a voltage of the internal resistor corresponding to the first bias current, and output the comparison result to the reference transistor.
7. The device of claim 1 , wherein the calibration unit comprises:
a calibration transistor coupled to the bias circuit;
a reference voltage generator configured to generate a reference voltage;
a comparator configured to compare the reference voltage with a voltage corresponding the third bias current through the calibration transistor; and
a control unit configured to generate the control signal based on the comparison result, and output the control signal to the calibration transistor as the adjustable resistor and a driver for calibration.
8. The device of claim 1 , wherein the internal resistor includes a low temperature-coefficient material.
9. A memory system comprising:
a driver circuit; and
a calibration device,
wherein the calibration device comprises:
a bias circuit configured to provide bias current; and
a calibration unit configured to generate a control signal for calibration of the driver circuit,
wherein the bias circuit includes an internal resistor and is configured to measure a second bias current generated by mirroring a first bias current through the internal resistor, and adjust the second bias current to generate the second bias current as a third bias current in a predetermined range, an eFuse is configured to store a DAC code corresponding to the third bias current, an external device connection unit configured to provide an input DAC code via a serial port and sense the second bias current via a common test pin in a manufacturing phase of the calibration device; and
wherein the calibration unit is configured to generate the control signal based on a comparison result between a reference voltage and a voltage generated based on the third bias current through an adjustable resistor.
10. The system of claim 9 , wherein the bias circuit is configured to
measure the second bias current, and adjust the second bias current to generate the third bias current, during the manufacturing phase of the calibration device, and
output the third bias current to the calibration unit during a normal operation of the calibration device.
11. The system of claim 10 , wherein the bias circuit comprises:
a current generation block including the internal resistor, configured to generate the first bias current flow through the internal resistor; and
a current digital-to-analog converter (DAC) configured to receive an input DAC code, and output the second bias current and the third bias current based on the DAC code and the first bias current.
12. The system of claim 11 , wherein during the manufacturing phase, the current DAC is configured to receive the input DAC code from an external device, and output the second bias current to the external device, and
during the normal operation, the current DAC is configured to receive the input DAC code from the eFuse, and output the third bias current to the calibration unit.
13. The system of claim 12 , further comprising:
a multiplexer coupled between the current DAC and one of the external device and the eFuse, configured to provide the current DAC with the input DAC code from one of the external device and the eFuse; and
a demultiplexer coupled between the current DAC and one of the external device and the calibration unit, configured to output the second bias current to the external device and output the third bias current to the calibration unit.
14. The system of claim 11 , wherein the current generation block comprises:
a reference transistor coupled between the current DAC and the internal resistor in series;
a bandgap voltage generator configured to generate a bandgap voltage; and
a comparator configured to compare the bandgap voltage with a voltage of the internal resistor corresponding to the first bias current, and output the comparison result to the reference transistor.
15. The system of claim 9 , wherein the calibration unit comprises:
a calibration transistor coupled to the bias circuit;
a reference voltage generator configured to generate a reference voltage;
a comparator configured to compare the reference voltage with a voltage corresponding the third bias current through the calibration transistor; and
a control unit configured to generate the control signal based on the comparison result, and output the control signal to the calibration transistor as the adjustable resistor and a driver for calibration.
16. The system of claim 9 , wherein the internal resistor includes a low temperature-coefficient material.