FemtoClock® NG Jitter Attenuator
and Clock Synthesizer
8V19N490B
Datasheet
Description
Features
The 8V19N490B 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.
▪ 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 to 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:
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.
• Four JESD204B channels (device clock and SYSREF
output) with two, four and six outputs
• One clock channel with two outputs
• One VCXO output
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.
▪ 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
The device is configured through a three-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 8V19N490B 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 Renesas.
• 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
Typical Applications
▪ Wireless infrastructure applications: GSM, WCDMA, LTE,
LTE-A
• Digital holdover and hitless switching
• Differential inputs accept LVDS and LVPECL signals
▪ SYSREF generation modes include internal and external
trigger mode for JESD204B
▪ Ideal clock driver for jitter-sensitive ADC and DAC circuits
▪ Low-phase noise clock generation
▪ Ethernet line cards
▪ Supply voltage: 3.3V
▪ SPI and control I/O voltage: 1.8V/3.3V (selectable)
▪ Package: 11 11 mm 100-CABGA
▪ Temperature range: -40°C to +85°C
▪ Radar and imaging
▪ Instrumentation and medical
©2021 Renesas Electronics Corporation
1
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