| 摘要 |
PROBLEM TO BE SOLVED: To simply extend a frequency range of an emitter follower circuit and adjust the frequency band. SOLUTION: The emitter output of a transistor(TR) 1 is fed to the base of a TR 2, and also fed to the base of a TR 3 via a resistor 6, the emitters of the TRs 2, 3 are connected in common, current mirror TRs 4, 5 supply the collector current of the TRs 2, 3, and the current mirror current is variably controlled with a control voltage from a control terminal 14 to control the frequency range. An emitter follower circuit consists of the TR 1 and resistors 6, 7, bases of the TRs 2, 3 are respectively connected across the resistor 6 and a base-emitter capacitance of the TRs 2, 3 is used for a speedup capacitor to extend the frequency range. |
