| 摘要 |
PURPOSE:To attain broad band with effective feedback and peaking by constituting a feedback resistor with a series circuit of the 1st and 2nd feedback resistors in a parallel feedback amplifier circuit, connecting a base of the 3rd transistor (TR) to a connecting point between the 1st and 2nd feedback resistors, a collector to a high potential power terminal and an emitter to the emitter of the 1st TR. CONSTITUTION:A feedback rate muA of a feedback path A is expressed in equation I with a voltage dividing ratio of an AC voltage and a feedback ratio muB of a feedback path B is expressed in equation II because an AC signal of a connecting point between feedback resistors RF1, RF2 is given to a base of a TR6, where Zin1, Zin2 are input impedances of TRs 6, 15 from the base when the RF1, RF2 are disconnected. Thus, the feedback ratio mut of the total circuit is given as mut=muA+muB. Since the Zin2 is the capacitive impedance in equation IIthe value at high frequency is small and the feedback ratio is decreased, the frequency is brought in broad band by the peaking acting like increasing the gain.
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