A CMOS current-input current-output binary hysteresis circuit is presented. The two switching values for output current to swing from high to low, and from low to high, are controlled externally and independently by two current sources. Also, the output high and low are controlled independently by another two current sources. Therefore, this circuit has full external controls. Also, through the use of bi-directional current mirrors, the operational range is extended to all four quadrants of the input-output plane. (C) 2002 Elsevier Science Ltd. All rights reserved.