| 摘要 |
PURPOSE:To stabilize operation against fluctuations of local oscillation electric power, by providing a circuit, composed of a quarter-wavelength line for an intermediate frequency and terminating resistance, between a connection point of a mixer diode and intermediate frequency amplification stage and the ground. CONSTITUTION:A signal inputted from input terminal 4 and local oscillation electric power are mixed by diode 1 and an intermediate frequency signal, after appearing at terminal 5 via microwave stopping filter 2, is amplified by intermediate- frequency preamplifier 3. Between terminal 5 and the ground, a quarter-wavelength line of high characteristic impedance for an intermediate frequency and a terminating resistance with a low resistance value are provided in series. Even if a decrease in local oscillation electric power increases the impedance of the diode, impedance variation viewed from the intermediate frequency amplifier decreases, and consequently the amplifier never gets unstable, so that a little characteristic deterioration occurs in normal operation. |
