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Apply low-cost, easy-to-use, low-noise crystal buffers

Crystal oscillators (XO) or voltage-controlled crystal oscillators (VCXO) enjoy great popularity in today’s consumer applications. There are crystals attached to the main processors, graphic chip, connectivity devices (GPS, WLAN, WiMAX, GbE) and application processors as well. Crystal oscillators are easy to use, feature very low noise, and are available in a wide range of frequencies. Often, however, there is a need for one frequency only, but with multiples copies of it, so using a simple clock buffer or a crystal-based clock-buffer solution can pay off. This article takes a closer look into “low-noise clock generation and buffering” in a single device.

The choice of using discrete crystals only, or a “crystal and buffer” solution, depends on a number of factors including how many devices need to be clocked, what are the frequencies, the board layout and jitter requirements. For multi-media applications, a typical 27MHz clock is required for the application-processor, the video-chip, and the audio-device. Instead of using three single 27MHz crystal-oscillators, one crystal combined with a buffer device can do it, and saves money as well. But, can a single crystal-buffer solution keep up with the low-noise performance of a discrete crystal?

This article will explore these issues and is presented at a single pdf file (no registration required). To read it, click here .

About the Author
Georg Becke is a system engineer with the Clock Products group at Texas Instruments Incorporated. He is Senior Member of Technical Staff at Texas Instruments. He received his MSEE and BSEE in Electronics and Data Processing from University (FH) in Munich, Germany. Georg can be reached at ti_gbecke@list.ti.com.

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