Fully integrated wide range low-jitter crystal oscillator clock generator

The CDCE421A is a high-performance, low phase noise clock generator. It has two fully-integrated, low-noise, LC-based voltage-controlled oscillators (VCOs) that operate in the 1.750-GHz to 2.350-GHz frequency range. It also features an integrated crystal oscillator that operates in conjunction with an external AT-cut crystal to produce a stable frequency reference for the phase-locked loop (PLL) based frequency synthesizer.

The output frequency (fOUT) is proportional to the frequency of the input crystal (fXTAL). The prescaler divider, feedback divider, output divider, and VCO selection set the output frequency with respect to fXTAL.

In the CDCE421A, the feedback divider is set automatically with respect to the prescaler setting. The product of the prescaler and the feedback divider should be between 60 and 64 as shown in to maintain a stable control loop.

The CDCE421A supports one differential LVDS clock output or one differential LVPECL output. All device settings are programmable through a proprietary simple serial interface (SSI).

The device operates in 3.3-V supply environment for both LVPECL and LVDS outputs and is characterized for operation from -40°C to +85°C. The CDCE421A is available in a QFN-24 4-mm × 4-mm package.

CDCE421 Users: The CDCE421A provides several device enhancements to the CDCE421.