Clock Jitter Attenuators, Jitter Cleaners, Phase-locked Oscillators, and VCXOs

IDT jitter attenuation and frequency translation products feature a PLL stage with VCXO technology to attenuate jitter and provide frequency translation. Jitter attenuators, also called jitter cleaners, are based on a low phase noise phase-locked oscillator (PLL) stage typically followed by a frequency divider. The integration of a jitter attenuator and frequency translator simplifies the circuit and minimizes the bill-of-materials (BOM). IDT’s rich portfolio of jitter attenuators and frequency translators come in varying levels of performance, power, and programmability to address the needs of virtually any application. IDT jitter attenuators support various single-ended and differential signalling levels such as LVCMOS, LVPECL, LVDS, HCSL, HSTL, or SSTL.

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About Jitter Attenuators (Jitter Cleaners)
A jitter attenuator (aka jitter cleaner) is used to reduce the magnitude of jitter on a given timing signal. Jitter can be defined as the undesired deviation from an ideal periodic timing signal, and may be observed in characteristics such as the frequency, phase, or amplitude of successive pulses. High levels of jitter can arise as a result of long traces, cables, and noisy system environments, producing undesired system behavior in high-performance applications. IDT’s jitter attenuators (jitter cleaners) use innovative phase-locked oscillators to lock on to a noisy clock signal and then output a high-quality signal to be sourced to other devices within the clock network.

About Voltage-controlled Oscillators (VCO oscillator) and VCXOs
A voltage-controlled oscillator (aka VCO oscillator) is an oscillator whose frequency or phase is immediately changed as a result of the voltage applied at the input. This feature makes VCO oscillators suitable as modulators, since a modulating signal can be applied at the input and will appear on the output as either a change in frequency or phase. VCO oscillators are typically integrated into the phase-locked oscillator. The integration of a voltage-controlled oscillator generally implies significant flexibility in the programmable output frequency range and system tuning, making them well suited for a wide range of applications.

A voltage-controlled crystal oscillator (VCXO) is optimized to oscillate a crystal instead of an input signal. Due to the high Q factor of quartz crystals, a VCXO allows for small variances in frequency, making them well-suited for fine adjustment of operating frequency. A VCXO is typically used for fine adjustment of the operating frequency. This can be useful to adjust the output frequency to match (or perhaps be some exact multiple of) an accurate external reference; or, where the system designer may want to reduce EMI by slightly changing the output frequency as a way to disperse the energy.