| 摘要 |
PURPOSE:To realize not only the miniaturization but the enhancement of the performance for the amplifier, by scuring a direct coupling for both the input signal switching part to share the gain control part of the color signal for the recording and reproduction and then avoiding the fluctuation of the DC bias of the electronic switch circuit at the switching part against the change of temperature. CONSTITUTION:Transistors TRQ10 and Q11 function as the exculsive switching TR to each other, and is thus turned on or off exclusively by the switch signal applied to the switch signal input terminals 21 and 22. At the same time, the TRQ3 forms the emitter-follower circuit which functions as a tempeature compensating dummy for the base-emitter voltage VBF of the TRs Q1 and Q2. And the 3rd DC bias power source E3 is selected so that the equation (2) may be satisfied under the base- emitter voltage defined as VF, the absolute temperature as T and the conditions of 0<=alpha<=1. As a result, no fluctuation is caused for the DC potential Eout of the output terminal and even with the change of temperature. |
