COMMUNICATION SOLUTIONS

PLL Clock Generation IC Has Superior Jitter Performance

For applications ranging from VGA graphics cards to Fibre Channel clock generation, the traditional method for generating the master clock signal has been to implement a single crystal oscillator. Historically, crystal oscillators have offered better jitter performance than silicon-based devices. However, these canned oscillators are complex to manufacture, and so are relatively expensive and require long lead times.

ON Semiconductor’s NB4N507A is a high-performance silicon PLL that delivers jitter performance comparable to crystal oscillators but offers far more design flexibility, a lower overall cost and greatly reduced lead times. With accuracy of 100 parts per million (ppm), the NB4N507A is a superior alternative to crystal oscillators with similar stability.



The device generates a clock signal ranging from 50MHz to 200MHz via an inexpensive reference crystal. With a maximum Root Mean Square (RMS) period jitter of less than 10ps, it delivers half the jitter (or noise) of competitive silicon PLL products.

Because the chip is fully configurable, it provides true design flexibility. For example, a single device can be used to generate different frequencies within a system and can be reused on future designs regardless of changes in timing requirements. In addition, silicon-based ICs like the NB4N507A are inherently much simpler to manufacture which leads to lower costs and vastly lower lead times.

The device can also be used to construct Voltage-Controlled and Temperature-Compensated Oscillators (VCXOs and TCXOs). Since the bandwidth of the PLL is guaranteed to be greater than 10MHz, it can track any modulation on the input up to this frequency. This property allows the construction of a low-frequency VCXO, whose output may be multiplied by the NB4N507A to produce a high-frequency operation. The principle can be extended into TCXO design because the output of the chip is phase-locked to the input, so that the NB4N507A has no temperature dependence.

Features

• Input crystal frequency of 10MHz to 27MHz
• Enables use of common low-cost crystal
• Differential PECL output clock frequencies of up to 200MHz
• Duty cycle of 48%/52%
• Operating range 3.0V to 5.5V
• Ideal for SONET applications and oscillator manufacturers
• Available in die form
• Lead-free packages available

Applications

• PECL clock generation
  • Networking
  • Communications
  • Computing
  • General purpose applications
• Crystal oscillator replacement

For further information, including the NB4N507A Datasheet, please click here.