Driver with resistance calibration capability

A semiconductor device comprising:

• a driver circuit comprising:
• a first variable resistor having a resistance configured to be adjusted responsive to a first resistance control signal;
• a first switch connected in series with the first variable resistor and configured to couple an output node to a first power supply node via the first variable resistor responsive to an input signal;
• a second variable resistor having a resistance configured to be adjusted responsive to a second resistance control signal;
• and
• a second switch connected in series with the second variable resistor and configured to couple the output node to a second power supply node via the second variable resistor responsive to the input signal;
• and
• a calibration circuit comprising:
• a third variable resistor that is a duplicate of the first variable resistor;
• a fourth variable resistor that is a duplicate of the second variable resistor;
• and
• a control circuit configured to generate respective ones of the first and second resistance control signals responsive to voltages across respective ones of the third and fourth variable resistors, wherein the control circuit comprises:
• a first current source circuit;
• a second current source circuit;
• a third switch coupled in series with the third variable resistor and configured to couple the first current source circuit to the first power supply node via the third variable resistor;
• a fourth switch coupled in series with the fourth variable resistor and configured to couple the second current source circuit to the second power supply node via the fourth variable resistor;
• and
• a digital code generation circuit configured to sense respective voltages at respective terminals of the third and fourth switches and to generate respective one of the first and second digital resistance control signals responsive to the sensed voltages.

A semiconductor device comprising:

• a driver circuit having an output resistance that is controllable responsive to a resistance control signal, wherein the driver circuit comprises a first variable resistor and is configured to couple an output node to a power supply node via the first variable resistor responsive to an input signal, wherein the first variable resistor comprises:
• a fixed resistor;
• a plurality of resistors;
• and
• a switching circuit configured to selectively couple the plurality of resistors in parallel with the fixed resistor responsive to the resistance control signal;
• and
• a calibration circuit configured to duplicate a resistance behavior of the driver circuit and to generate the resistance control signal responsive to the duplicated resistance behavior, wherein the calibration circuit comprises a second variable resistor that is a duplicate of the first variable resistor.