| 摘要 |
PURPOSE:To achieve 3-state or more switching softly and to prevent the production of pop tone, by alternatively operating a constant current transistor provided at a common emitter of three pairs of differential transistor circuits making the corresponding collectros common. CONSTITUTION:Further one pair of differential TRsQ5, Q6 are connected to 2 pairs of differential transistors (TRs)Q1-Q4 connected to the 1st and 2nd input terminals IN1, IN2, an input terminal IN3 is connected to the base of the TRQ5, and the base of the TRQ6 and the base of other TRsQ2, Q4 are connected to an output terminal OUT. Constant current sources TRsQ7-Q9 are connected to the common emitter of the TRsQ1, Q2 and Q3, Q4 and Q5, Q6 and also to a load constituting a current Miller circuit consisting of diode-connected TRsQ10, Q11. The TRsQ7-Q9 are alternatively operated with the constant current circuit I0 forming a control circuit and signals from the TRsQ13-Q19, allowing to perform switching 3-state or more softly and to avoid the production of pop tone. |
