| 摘要 |
PURPOSE:To obtain a signal synthesizing circuit which can set an analog value independently by independently providing current sources corresponding to signals and by summing all current source outputs by turning ON-OFF the corresponding current sources by respective signals. CONSTITUTION:Since voltage VB across voltage source 25 is nearly equal to the high voltage of an input signals, transistor TR23a is OFF as far as an input potential at input terminal is high. Next, when an input potential at input terminal 4a decreases low, TR23a conducts and a current determined by emitter resistance 24a flows to the collector of TR23a via resistance 16. Then, TRs 23b-23d operate similarly and currents flowing to respective collectors are mixed by resistance 16 in one, which is output from output terminal 18 via TR30. |
