Switch-controllable OTRA-based bistable multivibrators

Two bistable multivibrators based on the operational transresistance amplifier (OTRA) are presented. The first topology consists of only one OTRA and a positive feedback network. The second multivibrator utilises a single-pole double-throw (SPDT) switch along with a bias voltage source to shift the hysteresis loop into either the right-half-part or the left-half-part of the nu_i-nu_o plane. These two proposed circuits have a common attractive feature. That is, both clockwise and counter-clockwise hysteresis operations can be fulfilled with an additional SPDT switch connected to different configurations. In order to extend the applications, a general multiple-output configuration is also suggested. The presented bistable multivibrators are simple and versatile. The operation principles are described in detail. Theoretical analyses are verified by the experimental results on the prototype circuits.