a simplified temperature stabilized circuit provides a current which is proportional to a variable voltage by the use of branching transistor circuitry which fixes the voltage level of the supplied current , and controls its magnitude . the variable voltage is supplied through a reference resistor to the emitter of a first junction transistor having its base connected to the base of an identical junction transistor having its emitter grounded , thereby fixing the input voltage to the first transistor at a virtual ground potential . a third identical transistor has its base and emitter connected in parallel with the first transistor and carries an equal amount of current . current derived in parallel from the first and second transistor is positively proportioned relative to the current flowing in the collector path of the third transistor by a pair of mirror - connected transistors having suitable relative areas and load resistors . the desired temperature stabilized current is applied from the bases of the mirrored transistors to the ladder network of a digital to analog converter . two cascaded digital - to - analog circuits of this type provide a stable analog output voltage proportional to the product of the two numbers represented by the binary inputs .