| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a transimpedance type preamplifier capable of receiving signals of a plurality of transmission rates which are largely different from one another, securing a wide dynamic range with sensitivity according to the transmission rate and securing an optimal frequency band. <P>SOLUTION: In this preamplifier having an internal gain control part 13 and a transimpedance part 14, it has a decoder 15 which outputs a transmission rate information signal and controls the internal gain control part 13 and the transimpedance part 14 by the transmission rate information signal from the decoder. The internal gain control part 13 and the transimpedance part 14 are constituted so that a resistance value is digitally controlled by the on/off of switching elements by connecting the switching elements in parallel or in series to a plurality of resistors connected in parallel or in series. In addition, a feedback resistance value does not become zero or infinity by making at least one resistor among the plurality of resistors connected in series or in parallel always selected. <P>COPYRIGHT: (C)2006,JPO&NCIPI |
