| 摘要 |
PURPOSE: To provide a fast preamplifier circuit which can process a large common mode input area by using a single integrated circuit device form that contains plural input pads and at least a single output pad to be connected to a display. CONSTITUTION: This preamplifier circuit is formed in a single integrated circuit, and the amplifiers 42 (a to b), 44 and 46 and their Z-Comp external circuits 48, 50, 52 and 54 are harmonic or substantially equal to each other. When the length of a selected cable is kept within a range of 0 to 333 feet, an appropriate signal is supplied to an input pad 28 and a multiplexer 34 connects an input line 56 to an output line 58. If the cable length is set between 333 to 666 feet, an appropriate signal concerning a pad 30 instructs the multiplexer 34 to select a line 62 that is connected to the output side of the amplifier 44. If the cable length is included in a range of 666 to 1000 feet shown by an appropriate signal concerning an input pad 32, the multiplexer 34 selects a line 64 that is connected to the output side of the amplifier 46. |
