Advance Data Sheet

W3000 PLL Dual-Band Frequency Synthesizer

December 1999

Lucent Technologies Inc.

20

General rules for the values of these components have been derived many times

for reference. If:

p

tan

sec

1

T

ω

φ

−

φ

=

)

3

T

1

T

(

*

1

2

T

2

c

+

ω

=

2

REF

20

/

attn

)

F

*

2

(

1

10

3

T

π

−

=

where

φ = Phase margin required, normally 45° for a critically damped response.

p

c

(

)

(

)

[

]

















−

+

φ

+

+

+

+

+

+

φ

=

ω

1

)

3

T

1

T

(

*

tan

3

T

*

1

T

)

3

T

1

T

(

1

*

T3

*

T1

T3)

(T1

T3)

(T1

*

tan

2

2

2

c

atten = Attenuation provided by the third pole at the reference frequency.

The loop filter values can then be derived as:

2

/

1

2

2

c

2

2

c

2

2

c

2

c

PD

)

3

T

*

1

)(

1

T

*

1

(

)

2

T

*

1

(

*

N

*

Kvco

*

K

*

2

T

1

T

1

C

















ω

+

ω

+

ω

+

ω

=













−

=

1

1

T

2

T

*

1

C

2

C

2

C

2

T

1

R

=

The final pole, consisting of R2 and C3, should be chosen such that the following guidelines are followed:

10

1

C

3

C

≤

and

1

R

*

2

2

R

≥

1. Rohde, Ulrich L., Digital PLL Frequency Synthesizers Theory and Design, Prentice-Hall, 1983.