Monolithic bipolar diodes and their models

The AC performance of the diode-connected, bipolar junction transistor (BJT) is examined. The discussion covers the BJT's most common connection, its small-signal behavior, and the current repeater that uses the diode as an input device. Looking at the AC behavior reveals the strengths and weaknesses of various models and simulators, primarily SPICE. It is shown that these common circuits are classic cases where models can fail.<>