Clocks & Timing

Renesas FemtoClock™, FemtoClock Next Generation (NG), and FemtoClock 2 devices are advanced, high-performance clock-frequency synthesizers. Employing a simple, low-cost, fundamental-mode quartz crystal as the low-frequency reference these devices synthesize high-quality, low-jitter clock signals with less than 0.5 ps of RMS phase noise, up to 1.3GHz. The RC3 series also offers a jitter attenuation mode where it can take a noisy reference in and still provide 100fs jitter on its outputs.

FemtoClock devices are fully customizable, stand-alone solutions that generate reference frequencies allowing them to replace crystal and SAW oscillators in high-performance applications. This family of devices is often used to replace third overtone and high-frequency fundamental (HFF, inverted mesa) crystal oscillators or expensive surface acoustic wave (SAW) oscillators. They are more reliable, cost less, and are more readily available with shorter lead times.

Unlike fixed frequency oscillators, FemtoClocks are a frequency-synthesis technology (clock synthesizer) capable of multiple clock frequencies and more flexibility in any application. Because FemtoClocks are silicon IC-based clock devices, additional clock tree functions unavailable in a single function fixed-frequency oscillator can be integrated into a single device. The Renesas FemtoClock family delivers a wide range of device packages and capabilities, starting with small 8-pin TSSOP devices that provide one clean, low jitter clock signal, and 4mm x 4mm QFNs which provide 4 outputs. Also available are devices with more integrated functions, multiple outputs, multiple frequencies, and other more complex programmable synthesis functions.

PAM4 technology is enabling a major leap in data transmission rates in both communications and data center segments. This impacts the performance requirements of the timing source in such systems. The Renesas high-performance family of FemtoClock 2 delivers superior jitter performance with low power in a very small form factor, enabling placement of the clock anywhere on the board at the point of use. This greatly simplifies the design by eliminating the additive jitter associated with the extensive clock routing on the board.

Beyond PAM4, Renesas FemtoClock timing solutions are ideal reference clocks for almost any jitter-sensitive application. They are designed to provide a reference clock to PHYs, switches, ASICs, and network processors. The result is a simplified board design and layout, as well as improved time-to-market. Moreover, the FemtoClock family meets the low-jitter clock specification requirements of many interface standards, such as 10 Gigabit Ethernet, PCI Express®, Fibre Channel, and SONET. While generally optimized for synthesizing reference clock frequencies commonly used in communication applications, there are also a variety of FemtoClock devices with frequencies useful for CPU, memory, logic, and other general-purpose clocking applications, including ASICs, DSPs, CPUs, and memory; communication (including SONET/SDH and SPI4.2); HDTV video; networking (including 1Gb, 10 Gb, XAUI and 12Gb Ethernet); PCI Express; SERDES and PHY reference clocks; serial storage (SAS, SATA, fiber channel 4, 8 and 10Gb); and wireless infrastructure (including CPRI, RP3).

About Low-jitter Clocks

Jitter can be defined as the undesired deviation from an ideal periodic timing signal. Jitter may be observed in characteristics such as the frequency, phase, or amplitude of successive pulses. High levels of jitter can result in significant undesired system behavior in high-performance applications. Renesas offers the industry's leading portfolio of low-jitter clock synthesizers and phase-locked oscillators (PLL oscillators) to meet the needs of virtually any application.

Featured FemtoClock Devices

Part Number Description Datasheet Order
RC32504A FemtoClock™ 2 Jitter Attenuator or Clock Generator pdf_icon_for_table.png Buy Now arrow_icon_for_table.png
RC22504A FemtoClock™ 2 Clock Generator pdf_icon_for_table.png Buy Now arrow_icon_for_table.png

Product Selection Table

    Processing table
    Outputs (#)
    Output Type
    Output Freq Range (MHz)
    Inputs (#)
    Input Type
    Phase Jitter Max RMS (ps)
    Input Freq (MHz)
    Output Banks (#)
    Core Voltage (V)
    Output Voltage (V)
    Phase Jitter Typ RMS (ps)
    Part Number
    RC22504A
    FemtoClock™ 2 Clock Generator    		 4 HCSL, LVCMOS, LVDS 10 - 1000 2 Crystal, HCSL, LVCMOS, LVDS 0.1 25 - 312.5 4 1.8, 3.3 1.8 0.079
    RC22514A
    FemtoClock™ 2 Clock Generator    		 4 HCSL, LVCMOS, LVDS 10 - 1000 0 0.1 4 1.8, 3.3 1.8 0.079
    RC32504A
    FemtoClock™ 2 Jitter Attenuator or Clock Generator    		 4 HCSL, LVCMOS, LVDS 10 - 1000 3 Crystal, HCSL, LVCMOS, LVDS 0.1 5 - 1000 4 1.8, 3.3 1.8 0.079
    RC32514A
    FemtoClock™ 2 Jitter Attenuator or Clock Generator    		 4 HCSL, LVCMOS, LVDS 10 - 1000 3 Crystal, HCSL, LVCMOS, LVDS 0.1 1 - 800 4 1.8, 3.3 1.8 0.079
    841N4830I
    FemtoClock™ NG Crystal-To-HCSL Frequency Synthesizer    		 6 HCSL, LVCMOS, LVPECL 25 - 100 2 Crystal, HCSL, LVDS, LVPECL 0.34 25 4 3.3 3.3
    843N571I
    FemtoClock NG™ Clock Synthesizer    		 10 LVCMOS, LVPECL 25, 33.33, 100, 125, 156.25 2 Crystal, LVCMOS 25 5 3.3 3.3 0.212
    8T49N004I
    Programmable FemtoClock™ NG LVPECL/LVDS Clock Generator with 4-Outputs    		 4 LVDS, LVPECL 15.16 - 1250 2 Crystal, HCSL, LVDS, LVPECL 0.292 10 - 312.5 1 2.5, 3.3 2.5, 3.3 0.212
    8T49N006I
    Programmable FemtoClock™ NG LVPECL/LVDS Clock Generator with 6-Outputs    		 6 LVDS, LVPECL 15.16 - 1250 2 Crystal, HCSL, LVDS, LVPECL 0.292 10 - 312.5 1 2.5, 3.3 2.5, 3.3 0.212
    8T49N008I
    Programmable FemtoClock™ NG LVPECL/LVDS Clock Generator with 8-Outputs    		 8 LVDS, LVPECL 15.16 - 1250 2 Crystal, HCSL, LVDS, LVPECL 0.292 10 - 312.5 1 2.5, 3.3 2.5, 3.3 0.212
    8T49N012I
    FemtoClock™ NG Crystal-to-3.3V, 2.5V LVPECL/LVCMOS Clock Generator with Fanout Buffer    		 12 CMOS, LVPECL 15.16 - 1250 2 Crystal, HCSL, LVDS, LVPECL 0.26 10 - 312.5 3 2.5, 3.3 2.5, 3.3 0.19
    8T49N028
    Crystal-to-3.3V, 2.5V Multiple Frequency Clock Generator with Fanout Buffer    		 8 LVDS, LVPECL 15.16 - 1250 2 Crystal, HCSL, LVDS, LVPECL 0.292 10 - 312.5 4 2.5, 3.3 2.5, 3.3 0.212
    8T49N366I
    FemtoClock NG Triple Universal Frequency Translator    		 6 LVDS, LVPECL 0.98 - 1300 7 HCSL, LVCMOS, LVDS, LVHSTL, LVPECL, LVTTL 0.465 0.008 - 710 3 2.5 2.5 0.333
    8V41NS0412
    FemtoClock™ NG 12-Output Clock Generator    		 12 HCSL 10.91 - 2500 2 Crystal, HCSL, HSTL, LVCMOS, LVDS, LVHSTL, LVPECL 5 - 1000 4 3.3 3.3 0.095
    8V44N003I
    FemtoClock™ NG LVDS Clock Synthesizer    		 2 LVDS 50 - 1200 1 HCSL, LVCMOS, LVDS, LVPECL, Sine Wave 0.45 20 - 500 1 3.3 3.3 0.3
    8V49NS0312
    FemtoClock™ NG 12-Output Clock Generator    		 12 LVDS, LVPECL 10.91 - 2500 2 Crystal, HCSL, HSTL, LVCMOS, LVDS, LVHSTL, LVPECL 5 - 1000 4 3.3 3.3 0.089
    8V49NS0412
    FemtoClock™ NG 12-Output Clock Generator    		 12 LVDS, LVPECL 10.91 - 2500 2 Crystal, HCSL, HSTL, LVCMOS, LVDS, LVHSTL, LVPECL 5 - 1000 4 3.3 3.3 0.08
    RC22112A
    FemtoClock Clock Generator
    RC32508A
    FemtoClock 2 Jitter Attenuator or Clock Generator    		 8 HCSL, LVCMOS, LVDS 10 - 1000 3 Crystal, HCSL, LVCMOS, LVDS -2, 0.1 1 - 800 8 1.8, 3.3 1.8 0.067
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    Lab on the Cloud Demo for FemtoClock®2 Ultra-Low Phase Noise Synthesizer and Jitter Attenuator

    Demonstration of Renesas’ Lab on the Cloud virtual environment for FemtoClock®2 ultra-low phase noise synthesizer and jitter attenuator.

    Video List
    Lab on the Cloud Demo for FemtoClock®2 Ultra-Low Phase Noise Synthesizer and Jitter Attenuator
    FemtoClock2 Portfolio of Industry’s Smallest, Lowest Power 75fs Jitter Clocks

    News & Blog Posts

    Benefits of a Point-of-Use Clock for Jitter Optimization Blog Post Apr 27, 2021
    Renesas Expands FemtoClock Timing Portfolio for High-Performance Communications and Data Center Applications News Apr 26, 2021