| 摘要 |
PURPOSE:To improve the S/N of a waveform observed on a CRT by adding a series resistor to each emitter of transistors (TRs) constituting a differential amplifier and using a PN junction between the base and emitter of the TR as a load impedance. CONSTITUTION:One terminal of the 1st and 2nd resistors RA1, RA2 is connected respectively to the emitter of the 1st and 2nd TRs l, 2 and the PN junctin of TRs 4, 5 is used as the load impedance. Thus, the dynamic range of an input signal eA is increased by using the 1st and 2nd resistors RA1, RA2. Further, the resistance of the PN junction being the load impedance is varied attended with the change in a current 1c. Thus, the gain after a control amplifier CA is lowered more than a conventional value, and then the noise on a cathode ray tune CRT generated independently of the setting of an attenuator is lowered to be negligibly small.
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