| 摘要 |
PURPOSE:To attain stable circuit operation in the circuit integration of high frequency DC connection multi-stage coupling by inserting and using the 1st and 2nd filters. CONSTITUTION:The 1st filter circuit 11 is placed at the outside of an IC package, resonated with an inductance LG2, the function absorbing it is provided, then the 2nd filter circuit 12 is provided and an AC negative feedback is applied at frequencies other than specific frequencies. A series resonance circuit is constituted with a bonding inductance LG2 and a capacitor C1 in an example shown in Fig. in the 1st filter circuit 11, the effect of the LG2 is eliminated, the effect of an emitter resistor R13 of a transistor Q2 is eliminated near a desired frequency, a characteristic as shown in broken lines B in Fig. and a gain of a low frequency band is suppressed. Further, the characteristic of the amplifier circuit is as shown in Fig. D or D' by setting the 2nd filter circuit 12 shown in Fig., the selecting characteristic of the circuit is improved and the stability of the circuit is improved further.
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