8

ICS81006AKI REV A OCTOBER 2, 2006

ICS81006I

VCXO-TO-6 LVCMOS OUTPUTS

Oscillator

V

C

C

V

C

S1

C

L1

C

S2

C

L2

C

V

XTAL

VCXO (Internal)

Optional

➤

➤

➤

➤

Control Voltage

l

o

b

m

y

Sr

e

t

e

m

a

r

a

Ps

n

o

i

t

i

d

n

o

C

t

s

e

Tm

u

m

i

n

i

Ml

a

c

i

p

y

Tm

u

m

i

x

a

Ms

t

i

n

U

f

N

y

c

n

e

u

q

e

r

F

l

a

n

i

m

o

N

4

4

.

9

1z

H

M

f

T

e

c

n

a

r

e

l

o

T

y

c

n

e

u

q

e

r

F

0

2

±m

p

p

f

S

y

t

il

i

b

a

t

S

y

c

n

e

u

q

e

r

F

0

2

±m

p

p

e

g

n

a

R

e

r

u

t

a

r

e

p

m

e

T

g

n

i

t

a

r

e

p

O

00

7C

°

C

L

e

c

n

a

t

i

c

a

p

a

C

d

a

o

L

2

1F

p

C

O

e

c

n

a

t

i

c

a

p

a

C

t

n

u

h

S

4F

p

C

,

o

i

t

a

R

y

t

il

i

b

a

ll

u

P

0

2

20

4

2

R

S

Ee

c

n

a

t

s

i

s

e

R

s

e

i

r

e

S

t

n

e

l

a

v

i

u

q

E

0

2

l

e

v

e

L

e

v

i

r

D

1W

m

C

°

5

2

@

g

n

i

g

A

r

a

e

y

r

e

p

3

±m

p

p

n

o

i

t

a

r

e

p

O

f

o

e

d

o

M

l

a

t

n

e

m

a

d

n

u

F

Choosing a crystal with the correct characteristics is one of the

most critical steps in using a Voltage Controlled Crystal Oscillator

(VCXO). The crystal parameters affect the tuning range and

V

C

Control voltage used to tune frequency

C

V

Varactor capacitance, varies due to the change in

control voltage

accuracy of a VCXO. Below are the key variables and an example

of using the crystal parameters to calculate the tuning range of

the VCXO.

C

Load tuning capacitance used for fine tuning or

centering nominal frequency

C

Stray Capacitance caused by pads, vias, and other

board parasitics