| 摘要 |
PURPOSE:To perform the gain control and the bias control independently of each other and at the same time to secure the high frequency wide range characteristics, by providing a current adding circuit at the next stage of a variable gain circuit and amplifying the output signal of the current adding circuit to perform the bias control. CONSTITUTION:The signal given from a waveform signal source 1 is supplied to a variable gain circuit 2 to undergo the gain control through a gain variable signal source 5 and then supplied to a current adding circuit 3. A bias variable voltage source 6 is connected to the circuit 3 for execution of the bias control. The output of the circuit 3 is amplified by an amplifier circuit 4 for signal amplification. Then a desired signal is delivered. In other words, the circuit 2 is connected directly with the circuit 4 via the circuit 3 without using a coupling capacitor. Thus the gain control and the bias control are carried out independently of each other. The circuit 3 supplies the signal underwent the gain control through the circuit 2 and gives the voltage/current conversion to the gain controlled signal together with the bias control through the voltage source 6. Then the signal underwent both the gain and bias controls is delivered.
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