| 摘要 |
PURPOSE:To reduce varition in output voltage owing to the voltage variation of an external voltage supply, by interposing a constant-volatage generating circuit between the external positive voltage supply and one terminal of a load connected to collectors of several transistors for current switching. CONSTITUTION:The constant-voltage generating circuit depending upon the ground potential is interposed between one terminal of load Rc and external positive voltage supply (potential Vcc) in the circuit, several couples of Trs of which are supplied with a reference voltage at their bases and with an input signal voltage at bases and are connected in common to a constant-current supply at emitters. The constant-voltage generating circuit and constant-current supply consist of Trs Q1 and Q2, TrQ3 operating as a constant-current supply, and resistances R1 to R5. Here, denoting the forward junction voltage by VBE results in that the emitter potential of high-level output VHO=TrQ2 of the logic circuit is nearly (R1+R2 +R3)VBE/R3 and low-level output VOL is nearly VHO-R2RcVBE/R3R5, so that the output voltage will be under little influence of power voltage Vcc. |
