| 摘要 |
PROBLEM TO BE SOLVED: To supply an impedance adapting system realizing precise impedance adaptation based on the actual impedance of a transmission line. SOLUTION: A CPU 2 sequentially turns on the switch elements 7a to 7n of a resistor selection controller 3. The resistors R1 to Rn of a resistor array block 5 are connected in series to a damping resistor Rt in series between the output terminal A of a transmission side signal source 11 and the output terminal B of the resistor array block 5 as sequential adjustment resistors. An adjusting resistor by which the voltage Vb of the output terminal B becomes 1/2 of the voltage Va of the output terminal A is selected at every connection. When Vb=Va/2 is not satisfied, a resistor value where Vb/Va is most close to 1/2 is selected. The characteristic impedance of the transmission line 12 connected to the output terminal B and the sum of the output impedance of the transmission side signal source 11, the damping resistor Rt and the adjusting resistor are approximately impedance-adapted and the reflection noise of the signal of the transmission line 12 can be prevented or can remarkably be reduced.
|
