Frequency Synthesizing Tuning System with Saw Device

Recently many kinds of TV digital tuning systems have been developed. Especially in the United States the PLL frequency synthesizing method has been widely used. This system has advantages such as 10-key direct addressing, digital channel indication, high stability and accuracy of the local oscillator frequency, and so on. However it has also disadvantages such as harmonic interferences caused by a 1000 MHz ECL prescaler, and radiation from the prescaler which needs a large input level of 0.3 ~ 1 Vp-p.