| 摘要 |
PROBLEM TO BE SOLVED: To provide an attenuator the number of components of which can be reduced by easily available elements.SOLUTION: An attenuator includes an input resistor 190 having one end connected with the input terminal and the other end connected with an output terminal 191, and a variable resistor 100 connected with an output terminal 192. The variable resistor has at least a first transistor 131, a second transistor 132, first through fourth resistors 111-114, a first variable current source 151, a second variable current source 152, a first power supply 101, a second power supply 102, a feedback point 182, and an output point 181. The output point is connected with the output terminal. The first variable current source and second variable current source are changed so that a bias voltage appearing between the base-emitter of the first transistor is equal to a bias voltage appearing between the base-emitter of the second transistor. The first through fourth resistors, first power supply and second power supply are determined so that the voltage at the output point goes 0 V when the voltage inputted to the input terminal is 0 V. |
