U74HCT7046

CMOS IC

UNISONICTECHNOLOGIESCO.,LTD

16 of 16

www.unisonic.com.tw

QW-R502-851.A

APPLICATION INFORMATION(Cont.)

PLL Frequency Capture Range

(Phase comparator: PC1, PC2)

Loop filter component selection

ω

τ

)

(

j

τ

τ

π

π

/

f

2

1

f

2

L

Fig.13 Simple loop filter for PLL without offset; R3 ≥ 500 Ω.

R3

C2

INPUT

OUTPUT

ω

(a)

R4

1/ 3

τ

1/ 2

τ

m

)

(

j

(b) Amplitude Characteristic

(c) Pole-Zero Diagram

τ

-1/ 2

τ

-1/ 3

R4

R3

R4

m

+

=

Fig.14 Simple loop filter for PLL with offset; R3 + R4 ≥ 500 Ω.

Subject

Phase comparator Design considerations

PLL Locks on Harmonics at Centre Frequency

PC1

Yes

PC2

No

Noise Rejection at Signal Input

PC1

High

PC2

Low

AC Ripple Content when PLL is Locked

PC1

PC2

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exceed, even momentarily, rated values (such as maximum ratings, operating condition ranges, or

other parameters) listed in products specifications of any and all UTC products described or contained

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