| 摘要 |
PURPOSE:To ensure the stable working of a circuit which is obtained through integration of the high frequency DC connected multi-stage coupling, by leading a terminal outside an IC through a bonding wire of said IC and forming a filter circuit containing the inductance of the bonding wire from said terminal between the counter earths. CONSTITUTION:A sum current of the base current of a transistor (TR) Q2 and the current flowing through a resistance R12 is supplied to the emitter of the TRQ2. This sum current is also supplied to an earth (GND) through a resistance R13. Thus a potential decided by the product of the emitter current of the TRQ2 and the value of a resistance R13 is produced at the R13. This potential is fed back to the base of a TRQ1 through a resistance R14 and therefore the base potential of the TRQ1 is stabilized at a certain fixed point. Under such conditions, the input signals are amplified by both TRQ1 and Q2. However it is impossible to increase the gain by the emitter resistance R13 of the TRQ2 in terms of a high frquency. In this respect, a filter circuit 11 is inserted between earths from the emitter of the TRQ2. This reduces the feedback amount of a specific frequency and then stabilizes the circuit working.
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