ICS813001I Просмотр технического описания (PDF) - Integrated Circuit Systems

Номер в каталоге

Компоненты Описание

производитель

ICS813001I

DUAL VCXO W/3.3V, 2.5V LVPECL FEMTOCLOCK™ PLL

Integrated Circuit Systems 

Integrated

Circuit

Systems, Inc.

ICS813001I

DUAL VCXO W/3.3V, 2.5V LVPECL

FEMTOCLOCK™ PLL

VCXO CRYSTAL SELECTION

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 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.

➤ VC

Control Voltage

CV

➤

C

S1

Oscillator

VCXO (Internal)

XTAL

VC

- Control voltage used to tune

frequency

CV

- Varactor capacitance, varies due to

➤CV

the

change in control voltage

C C - Load tuning capacitance used for fine

L1, L2

tuning or centering nominal

frequency

CS1, CS2 - Stray Capacitance caused by pads,

C

S2

vias, and other board parasitics

CL1

CL2

➤

Optional

FIGURE 3. VCXO OSCILLATOR CIRCUIT

TABLE 6. EXAMPLE CRYSTAL PARAMETERS

Symbol Parameter

fN

Nominal Frequency

fT

Frequency Tolerance

f

Frequency Stability

S

Operating Temperature Range

CL

CO

C1, C2

ESR

Load Capacitance

Shunt Capacitance

Pullability Ratio

Equivalent Series Resistance

Drive Level

Aging @ 25°C

Mode of Operation

Test Conditions

Minimum Typical Maximum

14

24

±20

±20

0

70

12

4

220

240

20

1

±3 per year

Fundamental

Units

MHz

ppm

ppm

°C

pF

pF

mW

ppm

813001AGI

www.icst.com/products/hiperclocks.html

9

REV. A SEPTEMBER 2, 2005

Share Link: