Datasheet
Package Availability, Models, Samples & Pricing
General Description
The LMK04000 family of precision clock conditioners provides low-noise jitter cleaning, clock multiplication and distribution
without the need for high-performance voltage controlled crystal oscillators (VCXO) module. Using a cascaded PLLatinum architecture combined with an external crystal and varactor diode, the LMK04000 family provides sub-200 femtosecond (fs)
root mean square (RMS) jitter performance.
The cascaded architecture consists of two high-performance phase-locked loops (PLL), a low-noise crystal oscillator circuit,
and a high-performance voltage controlled oscillator (VCO). The first PLL (PLL1) provides a low-noise jitter cleaner function
while the second PLL (PLL2) performs the clock generation. PLL1 can be configured to either work with an external VCXO module
or use the integrated crystal oscillator with an external crystal and a varactor diode. When used with a very narrow loop
bandwidth, PLL1 uses the superior close-in phase noise (offsets below 50 kHz) of the VCXO module or the crystal to clean the
input clock. The output of PLL1 is used as the clean input reference to PLL2 where it locks the integrated VCO. The loop
bandwidth of PLL2 can be optimized to clean the far-out phase noise (offsets above 50 kHz) where the integrated VCO outperforms
the VCXO module or crystal used in PLL1.
The LMK04000 family features dual redundant inputs, five differential outputs, and an optional default-clock upon power up.
The input block is equipped with loss of signal detection and automatic or manual selection of the reference clock. Each
clock output consists of a programmable divider, a phase synchronization circuit, a programmable delay, and an LVDS, LVPECL,
or LVCMOS output buffer. The default startup clock is available on CLKout2 and it can be used to provide an initial clock
for the field-programmable gate array (FPGA) or microcontroller that programs the jitter cleaner during the system power up
sequence.
Design Tools
| Title | Size in Kbytes |
Date |
 |
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| Evaluation Board Instructions |
1416 Kbytes |
16-Jun-2009 |
View Online |
Download |
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Application Notes
| Title | Size in Kbytes |
Date |
 |
| AN-1734: Application Note 1734 Using the LMK03000C to Clean Recovered Clocks |
188 Kbytes |
2-May-08 |
Download |
AN-1734 (Chinese): Application Note 1734 Using the LMK03000C to Clean Recovered Clocks
|
338 Kbytes |
|
 |
| AN-1821: Application Note 1821 CPRI Repeater System |
1497 Kbytes |
15-May-08 |
Download |
| AN-1864: Application Note 1864 Phase Synchronization with Multiple Devices and Frequencies |
150 Kbytes |
24-Jun-08 |
Download |
| AN-1865: Application Note 1865 Frequency Synthesis and Planning for PLL Architectures |
151 Kbytes |
6-Feb-09 |
Download |
| AN-1910: Application Note 1910 LMK04000 Family Phase Noise Characterization |
6740 Kbytes |
15-Jan-09 |
Download |
[Information as of 4-Jul-2009]
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