SPICE SIMULATIONS OF CURRENT SOURCES BIASING OF LOW VOLTAGE

In this paper are presented simulation results for some bias circuits that operate at very low-voltage. It was started from two current mirror circuits: Nagata and Widlar. A Nagata current mirror is very suitable for battery operation because of current regulation and also for superior start-up circuitry. An inverse-Widlar current mirror is a non-linear current mirror for which the temperature characteristic is an inverse of the Widlar current mirror. A Nagata/inverse-Widlar current mirror is a proportional to absolute temperature (PTAT) current mirror or an inverse PTAT current mirror, depending on the relation between two resistors of circuit. As an application of these current mirrors, are presented a self-biasing Nagata current reference with start-up circuitry and a mutual-biasing Nagata/inverse-Widlar current reference with start-up circuitry. Also, a self-biasing Nagata voltage reference that is derived from the selfbiasing Nagata current reference by inserting a resistor is presented.