| 摘要 |
<p>PURPOSE:To supply a stable clock signal to an identification circuit while forming a timing extraction circuit of a high speed PCM signal transmission system by using a surface acoustic wave filter with a high Q required for timing extraction in the area of 1/H frequency division ratio. CONSTITUTION:An RZ signal given to an input terminal 5 is fed to a 1st timing extraction filter 11, where the clock signal synchronously with the clock frequency f0 is extracted with rough accuracy by an equalizing waveform of the inputted RZ signal. Then the signal is counted down by an optional frequency division ratio in a 1/N frequency division circuit 12. The clock signal subject to 1/N frequency division by the circuit 12 is supplied to a 2nd timing extraction filter 13. The a surface acoustic wave filter made of a crystal is used for the filter, then the wavelength of the surface acoustic wave is nearly 6.3mum. In the selection of the strip width of interdigital electrode and the gap equally, the strip width is nearly 1.6mum and the electrode pattern is made by a conventional photoetching technology.</p> |
