| 摘要 |
PURPOSE:To reduce the loss while holding the double reflection waves less than a given value, by performing low impedance drive for the surface acoustic wave filter. CONSTITUTION:The signal received with the antenna 31 is fed to the intermediate frequency circuit 35 constituted with the surface acoustic wave filter device via the high frequency amplifying circuit 32, frequency conversion circuit 33, and interface tank circuit 34, and this output is fed to the video amplification and detection circuit 40. With this constitution, the circuit 35 is constituted with the surface acoustic filter 39 and the compensation amplifying circuit 36. The emitter follower circuit 37 having very small output impedance is newly inserted between them as well known to drive the filter 39. Thus, the insertion loss of the filter 39 can be reduced, and suitable filter device for television receivers can be obtained with small transmission loss. |
