| 摘要 |
In an amplifying circuit using a grounded-emitter high frequency signal amplifying bipolar transistor, the value of impedance of a bias circuit as seen from the base terminal of the bipolar transistor is made optimum in the baseband frequency. More specifically, the resistance value of a base ballast resistor R<SUB>bias </SUB>connected to the base terminal of the bipolar transistor is set to a range within ±50% of [V<SUB>t</SUB>/I<SUB>bq</SUB>-(beta.R<SUB>e</SUB>+R<SUB>b</SUB>)] being "ideal resistance value", where I<SUB>bq </SUB>is static base current, beta is the gain of the transistor, R<SUB>e </SUB>and R<SUB>b </SUB>are parasitic resistance of the emitter terminal and base terminal, respectively, and V<SUB>t </SUB>is voltage defined by (kT/q).
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