Fully Integrated Fixed Frequency Low-Jitter Crystal Oscillator Clock Generator


Product details


Function Clock generator Number of outputs 1 Output frequency (Max) (MHz) 156.25 Core supply voltage (V) 3.3 Output supply voltage (V) 3.3 Input type LVCMOS Output type LVPECL Operating temperature range (C) -40 to 85 Features Signal 3.3-V supply, Chip-enable control pin Rating Catalog open-in-new Find other Clock generators

Package | Pins | Size

VQFN (RGE) 24 16 mm² 4 x 4 open-in-new Find other Clock generators


  • Single 3.3-V Supply
  • High-Performance Clock Generator, Incorporating Crystal Oscillator Circuitry with Integrated Frequency Synthesizer
  • Low Output Jitter: As low as 380 fs (RMS integrated between 10 kHz to 20 MHz)
  • Low Phase Noise at 312.5 MHz:
    • Less than -120 dBc/Hz at 10 kHz and -147 dBc/Hz at 10-MHz offset from carrier
  • Supports Crystal or LVCMOS Input Frequencies at 31.25 MHz, 33.33 MHz, and 35.42 MHz
  • Output Frequencies: 100 MHz, 106.25 MHz, 125 MHz, 156.25 MHz, 212.5 MHz, 250 MHz, and 312.5 MHz
  • Differential Low-Voltage Positive Emitter Coupled Logic (LVPECL) Outputs
  • Fully-Integrated Voltage-Controlled Oscillator (VCO): Runs from 1.75 GHz to 2.35 GHz
  • Typical Power Consumption: 300 mW
  • Chip Enable Control Pin
  • Available in 4-mm × 4-mm QFN-24 Package
  • ESD Protection Exceeds 2 kV (HBM)
  • Industrial Temperature Range: -40°C to +85°C
    • Low-Cost, Low-Jitter Frequency Multiplier

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The CDC421Axxx is a high-performance, low-phase-noise clock generator. It has an integrated low-noise, LC-based voltage-controlled oscillator (VCO) that operates within the 1.75 GHz to 2.35 GHz frequency range. It has an integrated crystal oscillator that operates in conjunction with an external AT-cut crystal to produce a stable frequency reference for a phase-locked loop (PLL)-based frequency synthesizer. The output frequency (fOUT) is proportional to the frequency of the input crystal (fXTAL).

The device operates in 3.3-V supply environment and is characterized for operation from -40°C to +85°C. The CDC421Axxx is available in a QFN-24 4-mm × 4-mm package.

The CDC421Axxx differs from the CDC421xxx in the following ways:

  • Device Startup
  • The CDC421Axxx has an improved startup circuit to enable correct operation for all power-supply ramp times.

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Similar but not functionally equivalent to the compared device:
CDCM61001 ACTIVE 1:1 Ultra Low Jitter Crystal-In Clock Generator CDCM61001 has similar fucntionality with much wider frequency range. CDCM61001 shall recommended over CDC421A156.

Technical documentation

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Type Title Date
* Datasheet Fully-Integrated, Fixed Frequency, Low-Jitter Crystal Oscillator Clock Generator datasheet May 05, 2009
Technical articles How to select an optimal clocking solution for your FPGA-based design Dec. 09, 2015
Technical articles Clocking sampled systems to minimize jitter Jul. 31, 2014
Technical articles Timing is Everything: How to optimize clock distribution in PCIe applications Mar. 28, 2014

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