XRT8020

650 MHZ CLOCK & CRYSTAL MULTIPLIER WITH LVDS OUTPUTS

NOVEMBER 2003

REV. 1.0.2

DESCRIPTION

The XRT8020 is a monolithic analog phase locked

loop that provides a high frequency LVDS clock out-

put, using a low frequency crystal or reference clock.

It is designed for SONET/SDH and other low jitter ap-

plications.The high performance of the IC provides a

very low jitter LVDS clock output up to 650 MHz, while

operating at 3.3 volts. The XRT8020 has a selectable

8x, 16x or 32x internal multiplier for an external crys-

tal or signal source. The Output Enable pin provides

a true disconnect for the LVDS output. The very com-

pact (4 x 4 mm) low inductance package is ideal for

high frequency operation.

APPLICATIONS

• Gigabit Ethernet

• SONET/SDH

• SPI - 4 Phase 2

• 8x, 16x or 32x Clock Multiplier for Computer and

Telecommunication Systems

FEATURES

• 575 MHz to 675 MHz operating range

• Low Output Jitter: 9ps rms typical at 622 MHz

• On Chip Crystal Oscillator Circuit

• Optimized for 15 to 40 MHz crystals

• Uses parallel fundamental mode crystal

• Selectable 8x, 16x or 32x multiplier

• Selectable

÷ 1or ÷ 2 LVDS output

• LVDS output meets TIA/EIA 644A Specification

(2001)

• 3.3V ±10% Low power CMOS: 80 mW typical

• -40°C to +85°C operating temperature

• Extremely small 16-lead QFN package

O

GND

FS1

OE

AGND

PD

AGND

(Crystal)

FS0

AGND

15-40 MHz

Crystal

XTAL1

XTAL2

Oscillator

Circuit &

Input Buffer

VCO

Calibration Logic

Phase

Detector

Charge

Pump

Loop

Filter

VCO

Selectable

Divider

LVDS Output

Feedback Divider

Voltage Reference

&

Bias Generator

R

EXT

10k

Ω

AV

DD

AV

DD

OV

DD

+3.3V

12 - 20 pF

12 - 20 pF

XRT8020

OUTP

OUTN