| 摘要 |
PURPOSE:To avoid increase of the circuit scale and to suppress the distrubance produced at an intermediate frequency signal band, by supplying a difference frequency signal to a PLL circuit from an output circuit which is connected approximately at the center of a microstrip line equal to 1/2 wavelength of the 2nd local oscillation signal and delivers a difference frequency signal between the 1st and 2nd local oscillation signals. CONSTITUTION:A microstrip line 60 is equal to 1/2 wavelength of the 2nd local oscillation signal and forms a 180 deg.-phase shifter 28. The 1st local oscillation signal is picked up from a +B power supply line by a series circuit consisting of a resistance 39 and a DC preventing capacitor 61 and a microstrip line and supplied to the junction between diodes 76 and 77. A mixer consisting of diodes 76 and 77 and the line 60 produces a difference signal between the input 1st and 2nd local oscillation signals. This difference signal is delivered approximately through the center of the line 60 and supplied to an amplifier consisting of a transistor 73 via an LPF consisting of a coil 51 and a capacitor 66. |
