Logic circuit for use in D/A converter having ECL-type gate structure.

摘要

A logic circuit outputs state signals of seven different kinds, on the basis of first, second and third digital signals. A first composite gate circuit (11) outputs a logical OR among the first to third digital signals as a first state signal. A first gate circuit (14) outputs a logical OR between the second and third digital signals as a second state signal. A second composite gate circuit (15) is supplied with a logical AND between the first and second digital signals, and outputs a logical OR between the supplied logical AND and the third digital signal as a third state signal. A third composite gate circuit (18) is supplied with a logical OR between the first and second digital signals, and outputs a logical AND between the supplied logical OR and the third digital signal as a fifth state signal. A second gate circuit (21) outputs a logical AND between the second and third digital signals as a sixth state signal. A fourth composite gate circuit (22) is supplied with a logical AND between the first and second digital signals, and outputs a logical AND between the supplied logical AND and the third digital signal as a seventh state signal. The third digital signal is output as a fourth state signal without being processed. Each of the above circuits has an emitter coupled logic structure. <IMAGE>