Analysis of Electrothermal Effects in Bipolar Current Mirrors

An extensive electrothermal analysis of current mirrors fabricated in silicon-on-glass and GaAs bipolar technologies is presented. Experimental results demonstrate that pronounced electrothermal effects may arise, which lead not only to a poor mirroring action, but also to a thermal instability occurrence for the output transistor. A simple relation is derived for predicting the instability onset Circuit and numerical simulations are employed to provide a deep insight into the underlying physics and suggest alternative solutions to counteract the electrothermal feedback.