Organize and Share your Electronics the way you want. Sign-Up for a free account now. It takes only 30 seconds!

Assess Power-Supply Noise Rejection in Low-Jitter PLL Clock Generators

Assess Power-Supply Noise Rejection in Low-Jitter PLL Clock Generators

This article discusses the effects of power-supply noise interference on PLL-based clock generators, and describes several measurement techniques for evaluating the resulting deterministic jitter (DJ). Derived relationships show how frequency-domain spur measurements can be used to evaluate timing-jitter behavior. Laboratory bench-test results are used to compare the measurement techniques, and demonstrate how to reliably assess the power-supply noise rejection (PSNR) performance of a reference clock generator.

Clock generators that employ PLLs are widely used in network equipment for generating high-precision and low-jitter reference clocks or for maintaining a synchronized network operation. Most clock oscillators give their jitter or phase-noise specification using an ideal, clean power supply. In a practical system environment, however, the power supply can suffer from interference due to on-board switching supplies or noisy digital ASICs. To achieve the best performance in a system design, it is important to understand the effects of such interference.

First we will examine the basic power-supply noise rejection (PSNR) characteristics of a PLL-based clock generator. We will then explain how to extract timing-jitter information from measurements taken in the frequency domain. These techniques are then applied and several different measurement methodologies are compared using lab bench testing. Finally, we will summarize the merits of the preferred approach.

Read more Here

 

More Articles to Read

Skill Sunday: Power Over Ethernet for Arduino
Skill Sunday: Power Over Ethernet for Arduino
More on Color TFT Displays ~ The Big Ones — 240 X 320
More on Color TFT Displays ~ The Big Ones — 240 X 320
Vertical Pole Climbing Robot
Vertical Pole Climbing Robot
ESP8266 Weather Station Projects
ESP8266 Weather Station Projects
Single tube Lethal Nixie clock
Single tube Lethal Nixie clock
How to make a simple 1 watt audio amplifier (LM386 based)
How to make a simple 1 watt audio amplifier (LM386 based)
Flashing Binaries to DRA7xx Factory Boards Using Device Firmware Upgrade
Flashing Binaries to DRA7xx Factory Boards Using Device Firmware Upgrade
Dot² isn’t your typical coffee table
Dot² isn’t your typical coffee table
Debugging ARM Cortex-M0+ HardFaults
Debugging ARM Cortex-M0+ HardFaults
EMP Jammer build
EMP Jammer build

Top




Shares