Description

The 8V19N490 is a fully integrated FemtoClock® NG jitter attenuator

and clock synthesizer designed as a high-performance clock solution

for conditioning and frequency/phase management of wireless base

station radio equipment boards. The device is optimized to deliver

excellent phase noise performance as required in GSM, WCDMA,

LTE, and LTE-A radio board implementations. The device supports

JESD204B subclass 0 and 1 clocks.

A two-stage PLL architecture supports both jitter attenuation and

frequency multiplication. The first stage PLL is the jitter attenuator

and uses an external VCXO for best possible phase noise

characteristics. The second stage PLL locks on the VCXO-PLL

output signal and synthesizes the target frequency.

The device supports the clock generation of high-frequency clocks

from the selected VCO and low-frequency synchronization signals

(SYSREF). SYSREF signals are internally synchronized to the clock

signals. Delay functions exist for achieving alignment and controlled

phase delay between system reference and clock signals and to

align/delay individual output signals. The four redundant inputs are

monitored for activity. Four selectable clock switching modes are

provided to handle clock input failure scenarios. Auto-lock,

individually programmable output frequency dividers, and phase

adjustment capabilities are added for flexibility.

The device is configured through a 3-wire SPI interface and reports

lock and signal loss status in internal registers and via a lock detect

(LOCK) output. Internal status bit changes can also be reported via

the nINT output. The 8V19N490 is ideal for driving converter circuits

in wireless infrastructure, radar/imaging, and

instrumentation/medical applications. The device is a member of the

high-performance clock family from IDT.

Features

▪ High-performance clock RF-PLL with support for JESD204B

▪ Optimized for low-phase noise: -150dBc/Hz (800kHz offset;

245.76MHz clock)

▪ Integrated phase noise of 80fs RMS typical (12kHz–20MHz)

▪ Dual-PLL architecture

▪ First PLL stage with external VCXO for clock jitter attenuation

▪ Second PLL with internal FemtoClock NG PLL: 2949.12MHz

▪ Six output channels with a total of 19 outputs, organized in:

— Four JESD204B channels (device clock and SYSREF output)

with two, four and six outputs

— One clock channel with two outputs

— One VCXO output

▪ Configurable integer clock frequency dividers

▪ Supported clock output frequencies include: 2949.12, 1474.56,

983.04, 491.52, 245.76, and 122.88MHz

▪ Low-power LVPECL/LVDS outputs support configurable signal

amplitude, DC and AC coupling and LVPECL, LVDS line

terminations techniques

▪ Phase delay circuits:

— Clock phase delay with 256 steps of 339ps and a range of 0 to

86.466ns

— Individual SYSREF phase delay with 8 steps of 169ps

— Additional individual SYSREF fine phase delay with 25ps

steps

— Global SYSREF signal delay with 256 steps of 339ps and a

range of 0 to 86.466ns

▪ Redundant input clock architecture with four inputs, including:

— Input activity monitoring

— Manual and automatic, fault-triggered clock selection modes

— Priority controlled clock selection

— Digital holdover and hitless switching

— Differential inputs accept LVDS and LVPECL signals

▪ SYSREF generation modes include internal and external trigger

mode for JESD204B

▪ Supply voltage: 3.3V

▪ SPI and control I/O voltage: 1.8V/3.3V (selectable)

▪ Package: 11  11mm 100-CABGA

▪ Temperature range: -40°C to +85°C