Description
The 8T79S308 is a fully integrated signal fanout buffer for
high-performance, low additive phase noise applications. The
main function of the device is the distribution and fanout of
high-frequency clocks or low-frequency synchronization signals.
The 8T79S308 is optimized to deliver very low phase noise clocks
and precise, low-skew outputs, low device-to-device skew
characteristics and fast output rise/fall times help the system
design to achieve deterministic clock phase relationship across
devices.
The device distributes the input signals (IN_0, IN_1) to two fanout
banks. A input select logic allows the device to operate as
1:8 buffer, dual 1:4 buffers, and to cross the input signals.
The propagation delay in both outputs banks is designed for equal
delay to support fixed phase relationships between both banks. All
outputs are very flexible in LVPECL/LVDS output style
configuration, output signal termination, and allow both DC and
AC coupling. Outputs can be individually disabled through a serial
interface.
The device is packaged in a lead-free (RoHS 6) 40-VFQFPN
package. The extended temperature range supports wireless
infrastructure, telecommunication, and networking end equipment
requirements. The 8T79S308 is a member of the
high-performance clock family from IDT.

Features
▪ High-performance, flexible clock/data/1PPS fanout buffer
▪ Low phase noise floor: -160dBc/Hz (156.256MHz clock)
▪ Integrated phase noise of < 65fs RMS typical (12kHz–20MHz)
▪ Flexible input selection
• 1:8 Fanout modes
• Dual 1:4 Buffer fanout modes
▪ Eight differential outputs, organized in two banks of four
outputs
▪ Low-power LVPECL/LVDS outputs support DC and AC
coupling and LVPECL, LVDS line terminations techniques
▪ Individually configured outputs through an I2
C interface
• LVPECL/LVDS output style, HCSL compatible (AC-coupled)
• Output amplitude
• Output enable
▪ Supported clock frequency range: 0 to 3GHz
▪ Core and output supply voltage modes:
• 3.3V core, 3.3V, 2.5V, and 1.8V output supply
• 2.5V core, 2.5V, and 1.8V output supply
▪ Selectable I2
C I/O interface voltage: 1.8V and VDD
▪ Integrated low dropout regulators (LDOs) for excellent power
supply noise rejection
▪ Package: 6 × 6 mm 40-VFQFPN
▪ Temperature range: -40°C to +105°C