| 摘要 |
PURPOSE:To change the transmission speed dependent on the bands without exchanging the parts when a preamplifier is applied to a receiving data link by changing the resistance value of a variable resistor of a power control part to apply the changed resistance value to an amplifying part, thereby changing the band of the amplifying part. CONSTITUTION:The value of the power voltage applied to the power terminal 1 of an amplying part II for LPF characteristics is changed with the conversion of the resistance value of a variable resistor R1. Consequently, the band of the part II is also changed. Therefore the resistance value of the resistor R1 is changed in accordance with the change of the transmission speed and the frequency band is changed to cope with the change of the resistance value. Thus it is possible to obtain a preamplifier which is used to constitute a receiving data link so as to secure the communication of data at different transmission speeds without exchanging the parts. |
