The sensitivity of a diode thermometer depends on how much the voltage changes for a given temperature change, with the current remaining constant. What is the sensitivity for this diode thermometer, operated at 100 mA, for a temperature change from 25°C to 150°C?

(a) +0.2 mV/°C;

(b) +2.0 mV/°C;

(c) -0.2 mV/°C;

(d) -2.0 mV/°C.

The current€“voltage characteristics of a forwardbiased p-n junction diode depend strongly on temperature, as shown in the figure. As a result, diodes can be used as temperature sensors. In actual operation, the voltage is adjusted to keep the current through the diode constant at a specified value, such as 100 mA, and the temperature is determined from a measurement of the voltage at that current.

0.15 0.10 0.05 T = 150 C T = 25 C 0.2 0.4 0.6 0.8 Voltage (V) Current (A)