Calibration devices for i/o driver circuits having switches biased differently for different temperatures

A calibration circuit is connected to an input/output driver, a voltage bias generator is connected to the calibration circuit and the input/output driver, and a temperature sensor is connected to the voltage bias generator. The calibration circuit and input/output driver each include a bank of resistors and corresponding switches. Bodies of the switches are connected to the voltage bias generator, and the switches are biased by a bias signal output from the voltage bias generator. The calibration circuit includes a comparator device connected to the switches and to a reference resistor. Activation and deactivation of selected ones of the switches is made to match the reference resistor. Also, the voltage bias generator adjusts the bias signal when a temperature change is sensed by the temperature sensor. Thus, the switches change current flow as the bias signal changes, without changing which of the switches are activated or deactivated.