| 摘要 |
PURPOSE:To hold the level of a signal which appears at an output terminal invariably constant by using an FET, etc., as a switching element and controlling the gains of switching parts at switching time. CONSTITUTION:Gains, when switching circuits included in switching parts 8-1- 8-4 composed of variable gain amplifier circuits using FETs, etc. are on, are denoted as G1-G4, and the degrees of coupling of coupling parts are equalized to C. In this case, path gains between input terminals 2-1 and 2-2, and output terminals 2-3 and 2-4 are as shown in a table. In case the gains G1-G4, when the switching circuits are on, are set by a control signal so that (1-C)G1=G2= (1-C)<2>G3=(1-C)G4 in the table, the output levels at the output terminals 2-3 and 2-4 are held invariably constant regardless of connection states by inputting signals with the same level to the input terminals 2-1 and 2-2. |
