High efficiency base current helper

摘要

High efficiency base current helper to improve the accuracy of current mirrors particularly useful for current mirror utilizing relatively low beta bipolar junction transistors. The high efficiency base current helper utilizes two feedback loops, the first attempting to force the bias rail voltage to a mirror reference voltage and the second sensing excess current in the first loop and forcing it to match a reference level. This causes the first loop to be biased with no more excess current than desired for any process or temperature condition yielding dramatic reductions in wasted bias current. A specific exemplary embodiment is disclosed.