Low-Noise Phase-Locked Loop Filter

The CLC5801 is extremely useful as a Phase-Locked Loop

filter in such applications as frequency synthesizers and data

synchronizers. The circuit of

Figure 14 implements one pos-

sible PLL filter with the CLC5801.

Printed Circuit Board Layout

Generally, a good high-frequency layout will keep power

supply and ground traces away from the inverting input and

output pins. Parasitic capacitances on these nodes to

ground will cause frequency response peaking and possible

circuit oscillation, see OA-15 for more information. National

includes an evaluation board with samples as a guide for

high frequency lay-out and as an aid in device testing and

characterization.

DS101307-43

FIGURE 13. Equalizer Frequency Response

DS101307-44

FIGURE 14. Phase-Locked Loop Filter

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