A silicon diode can be used to measure temperature by...

A silicon diode can be used to measure temperature by operating the diode at a fixed forward-bias current. The forward-bias voltage is then a function of temperature. At $T=300 \mathrm{~K}$, the diode voltage is found to be $0.60 \mathrm{~V}$. Determine the diode voltage at (a) $T=310 \mathrm{~K}$ and (b) $T=320 \mathrm{~K}$.

A silicon diode can be used to measure temperature by operating the diode at a fixed forward-bias current. The forward-bias voltage is then a function of temperature. At $T=300 \mathrm{~K}$, the diode voltage is found to be $0.60 \mathrm{~V}$. Determine the diode voltage at
(a) $T=310 \mathrm{~K}$ and
(b) $T=320 \mathrm{~K}$.

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Key Concepts

Forward Bias Diode Operation

A forward-biased diode is one in which a small voltage is applied such that the p-n junction conducts current exponentially with respect to the applied voltage. This principle allows for predictable voltage behavior under a constant current, which is essential for applications like temperature sensing, where the diode's voltage drop serves as an indicator of changes in temperature.

Temperature Coefficient

The forward voltage drop of a silicon diode typically decreases with increasing temperature—an effect quantified by its temperature coefficient, often around -2 mV/°C for silicon. This predictable change in voltage as temperature varies enables the diode to act as a temperature sensor when operated at a fixed bias current, translating voltage measurements directly into temperature readings.

Semiconductor Junction Behavior

The operation of a diode is fundamentally governed by the behavior of the semiconductor p-n junction, which exhibits an exponential current-voltage relationship. The characteristics of the junction, including barrier potential and carrier concentration, are temperature-dependent. This dependency results in the forward voltage drop decreasing with increasing temperature, making the diode useful for monitoring temperature changes in electronic circuits.

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