Stability and Startup of Non Linear Loop Circuits

The reliable analysis of DC operating point in circuits with positive feedback topology is often challenging, and frequently performed with ad hoc methods. These techniques are often error prone and lead to the frequent use of sub-optimal or unnecessary additional circuits for the stabilization or determination of the operating point (startup circuits). We present a simple and reliable technique for the determination of “stable” circuit solutions, that is based on the use of available circuit simulators and hence takes advantage of accurate device models. The method has been experimentally validated on a self-biasing current generator fabricated with a standard 0.18 μm CMOS process.