FS8308 datasheet(9/15 Pages) PTC

부품명	FS8308

상세설명	Low Power PLL Frequency Synthesizer IC

PDF	15 Pages

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제조업체	PTC [Princeton Technology Corp]

홈페이지	http://www.princeton.com.tw

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9 / 15 page

Adv a nc e Inform ation

FS8308

Page 9

April 2003

Phase/Frequency Detector (PFD)

The PFD compares an internal input frequency divider output signal, f

V, with an internal

reference frequency divider output signal, f

R, and generates an error signal, DO, which is

proportional to the phase error between f

V and fR. The DO output is intended for use with

a passive filter as shown in Fig. 2.

Lock Detector (LD)

When phase comparator detects phase difference, LD terminal outputs “L”. When phase

comparator locks, LD terminal outputs “H”. On standby, outputs “H”. The criteria for lock

condition is that the phase difference between f

V and fR is less than 2/xin and continues for

more than three consecutive times.

The input/output waveforms for the PFD and LD are shown in Fig. 3.

Fig. 2 – Passive low-pass filter circuit

Fig. 3 – PFD input/output waveforms

to VCO

high-Z

< 2/xin

2/xin

FS8308 데이터시트(PDF) 9 Page - Princeton Technology Corp