| 摘要 |
PROBLEM TO BE SOLVED: To provide a hybrid circuit apparatus usable up to a high frequency and for producing low noise. SOLUTION: The hybrid circuit apparatus includes: a reception amplifier for outputting a differential signal between first and second reception terminals; two variable gain amplifiers respectively driving first and second transmission terminals; and four resistors for interconnecting the first and second transmission terminals and the first and second reception terminals. One of the resistors connected to the same transmission terminal has a lower resistance than that of the other resistor and the resistors with a high resistance and a low resistance connected to the different transmission terminals are connected to the same reception terminal. Further, the resistance of the resistors is selected so that the impedance viewed from the first reception terminal is equal to an impedance equivalent to the impedance of a transmission line. Noise generated in the variable gain amplifiers is respectively supplied to the two reception terminals, wherein the noise is cancelled with each other, resulting in attaining low noise. COPYRIGHT: (C)2006,JPO&NCIPI
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