The temperature dependence of PIN diode attenuators

The results of a study on PIN diode electrical parameters that ultimately affect the temperature dependence of PIN diode attenuators are presented. It is shown that device passivation and geometry play a major role in governing the resistance-temperature coefficient in PIN diodes. Large capacitance diodes of any passivation are shown to tend toward negative resistance coefficients, indicating that shunt attenuators constructed with these devices will show attenuation levels increasing with temperature. Low-capacitance silicon dioxide passivated diodes (0.1 pF and smaller) typically exhibit resistance-temperature coefficients in the range of -0.1% to +0.1%/ degrees C, corresponding to very small changes of attenuation with temperature. The variation of stored charge with temperature is shown to be a good predictor of the temperature dependence of the PIN diode resistance and ultimately its performance in attenuator applications.<>