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.


  • High-performance, flexible clock/data/1PPS fanout buffer
  • Low phase noise floor: -160dBc/Hz (156.56MHz clock)
  • Integrated phase noise of 50fs RMS typical (12kHz–20MHz)
  • Flexible input selection (single fanout, dual buffer, switch)
  • Eight differential outputs, organized in two banks of four outputs
  • Low-power LVPECL/LVDS outputs
  • Individually configured outputs through an I2C interface (style, amplitude, enable)
  • Supported clock frequency range: 0 to 3GHz
  • 3.3V/2.5V core and 3.3V/2.5V/1.8V output supply voltage
  • Selectable I2C 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

Product Options

Orderable Part ID Part Status Pkg. Code Pkg. Type Lead Count (#) Temp. Grade Pb (Lead) Free Carrier Type Buy Sample
8T79S308NLGI Active NLG40P2 VFQFPN 40 I Yes Tray
8T79S308NLGI8 Active NLG40P2 VFQFPN 40 I Yes Reel
8T79S308NLGI/W Active NLG40P2 VFQFPN 40 I Yes Reel

Technical Documentation

Title Other Languages Type Format File Size Date
Datasheets & Errata
8T79S308 Datasheet Datasheet PDF 511 KB Aug 10, 2018
Application Notes & White Papers
AN-828 Termination - LVPECL Application Note PDF 229 KB Jul 5, 2016
AN-846 Termination - LVDS Application Note PDF 50 KB May 12, 2014
AN-844 Termination - AC Coupling Clock Receivers Application Note PDF 82 KB May 12, 2014
AN-842 Thermal Considerations in Package Design and Selection Application Note PDF 403 KB May 11, 2014
AN-835 Differential Input with VCMR being VIH Referenced Application Note PDF 77 KB May 10, 2014
AN-840 Jitter Specifications for Timing Signals Application Note PDF 349 KB May 7, 2014
AN-834 Hot-Swap Recommendations Application Note PDF 67 KB May 5, 2014
AN-833 Differential Input Self Oscillation Prevention Application Note PDF 94 KB May 5, 2014
AN-836 Differential Input to Accept Single-ended Levels Application Note PDF 37 KB May 5, 2014
AN-827 Application Relevance of Clock Jitter Application Note PDF 1.06 MB Apr 23, 2014
AN-815 Understanding Jitter Units Application Note PDF 476 KB Apr 23, 2014
AN-805 Recommended Ferrite Beads Application Note PDF 38 KB Jan 14, 2014
Timing Solutions Products Overview Overview PDF 4.11 MB Oct 31, 2018
IDT Clock Generation Overview 日本語 Overview PDF 1.83 MB Apr 28, 2016
IDT Clock Distribution Overview 日本語 Overview PDF 3.79 MB Apr 24, 2016
IDT Fanout Buffers Product Overview Product Brief PDF 739 KB Feb 16, 2015
High-Performance, Low-Phase Noise Clocks Buffers product brief Product Brief PDF 378 KB Aug 13, 2012

Software & Tools

Title Other Languages Type Format File Size Date
8T79S308 IBIS Model Model - IBIS ZIP 124 KB Jan 9, 2019