| 摘要 |
PURPOSE:To improve the response speed against a change in the frequency or temperature by preparing the frequency characteristic or temperature characteristic of an amplifier in advance as a correction table, applying coarse gain correction through the use of the table and using minute adjustment of gain by a feedback loop in common. CONSTITUTION:Frequency correction and temperature correction tables 7, 9 are tables for gain correction based on the frequency characteristic and the temperature characteristic of an amplifier measured in advance and generate gain correction quantities VF, VT. The correction quantities VF, VT are added by an adder 10 to control a variable attenuator 1. Through the operation above, coarse output level control correcting the frequency characteristic and temperature characteristic of the amplifier 2 at a high speed is applied. Then the level is compared with a reference level VR from a reference voltage generator 6 at a level comparator 6 to obtain a gain correction VE correcting the residual error. The correction VE is added to the coarse correction quantities VF, VT at the adder 10 to apply accurate level control. |
