| 摘要 |
PURPOSE:To prevent effectively leakage of local oscillation frequency, by providing an N type epitaxial layer between the 1st and 2nd separation layers and connecting a power supply line with the highest potential to this epitaxial layer. CONSTITUTION:A chip is divided into a block 1 of a local oscillation circuit and a block 2 other than the oscillation circuit. The block 1 is surrounded with an N type epitaxial layer 4 clipped with separation layers 8, 8' by P<+> diffusion, aluminum wiring 3 is made along the layer 4 and the wiring is connected with the layer 4 at a contact window 5. The wiring 3 is connected to the highest potential. This constitution can be expressed with an equivalent circuit as shown in figure. In this circuit, the impedance between other circuit blocks connected to a signal source 12 and an output terminal 13 is higher and since the intermediate part of each capacitor Cj is grounded with a comparatively low impedance, the leakage from the local oscillation block can remarkably be reduced. |
