| 摘要 |
PURPOSE:To obtain an attenuation circuit having the capacity for phase inverting control and wide input dynamic range by using an attenuator having a mixer whose operating region is decided by carrier so as to mix a signal wave at a control signal with a sign and attenuate the result. CONSTITUTION:A signal wave A and a carrier signal C which has a sufficiently large level to a level of the signal wave A and a frequency selected taking a frequency component formed by multiplying the signal wave A and the carrier C at an attenuator 21 of the post-stage into consideration and decides the operating region of the attenuator 21, are coupled by a coupler 31. The phase of a coupled signal D is controlled for shift by 0 deg. or 180 deg. depending on the positive or negative sign of a control signal B having a sign at the attenuator 21, and the attenuation is controlled by a voltage (current) and outputted. An output signal D1 is inputted to a filter circuit 32, a required signal wave only is extracted and outputted. |
