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PECL,LVDS Crystal Oscillator

PECL,LVDS Crystal Oscillator. Update: 2005/07/27 Application Engineer: Arvin Chiang. What are ECL,PECL and LVPECL Circuits?. ECL an acronym that stands for ( E mitter- C oupled L ogic)

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PECL,LVDS Crystal Oscillator

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  1. PECL,LVDS Crystal Oscillator Update: 2005/07/27 Application Engineer: Arvin Chiang

  2. What are ECL,PECL and LVPECL Circuits? • ECL an acronym that stands for (Emitter-Coupled Logic) • The "P" in PECL stands for positive. PECL Circuits are generally identical to ECL circuits, except the VCC supply is 5 V and the VEE supply is ground. There are special PECL devices that are designed strictly for +5 V supply only. • LVPECL Circuits are PECL circuits designed for use with VCC = 3 V or 3.3 V, the same supply voltage as for Low Voltage CMOS devices.

  3. What is LVDS? • LVDS is defined in the ANSI/TIA/EIA-644. • LVDS,an acronym that stands for (Low Voltage Differential Signaling) • It is a low voltage, low power, low jitter,differential technology used primarily for point-to-point and multi-drop cable driving applications.

  4. Where are PECL LVDS used? • The LVDS standard was created to address applications in the data communications, telecommunications, server, peripheral and computer markets where high-speed data transfer is necessary.

  5. Supply Voltage 5V 4V 3V 2V 1V Signal Level Comparison Output Level VOH VOH VOH 4.1 4.10 90% VDD 3.20 VOL VOL 3.20 VOH_Min 2.4 VOH 2.35 VOH 1.42 1.60 VOL VOL 1.07 VOL_Max VOL 0.4 10% VDD TTL CMOS ECL PECL LVPECL LVDS

  6. Dual Design ! Out of Date Crystal Oscillator + Translator Buffers (Differential Output) CMOS Output Crystal Oscillator PECL, LVDS Differential Output IC VDD VDD Chipset Q_Bar Input Amplifier Oscillator AC coupling Q CMOS Output PECL or LVDS Output

  7. Single Design ! It is the Trend! PECL or LVDS Differential Output Crystal Oscillator VDD Q_Bar Chipset PECL or LVDS Oscillator IC Q PECL or LVDS Output

  8. Comparison of Design Design Dual Design Single Design Dimensions > 50 35 Area (mm2) Layout space Bigger Smaller Current (Max) 100~150 mA 50 ~ 100 mA RMS Phase Jitter Not so Good Very Good (12KHz ~20MHz) <4 ps <1 ps Win

  9. PECL / LVDS Crystal Oscillator Specification • OT Type • Standard Frequency : 38.88, 62.5, 77.76, 100, 106.25, 125, 155.52, 156.25 , 159.375, 161.1328, 164.355469, 167.3316, 187.5, 212.5 MHz • Frequency Stability : +/- 50 ppm (+/-25 ppm ,Available) • Temp. Range :-20oC ~ +70oC (-40 oC ~ +85 oC, Available) • Supply voltage : DC +3.3V / 2.5V • Supply Current : 100mA (max, PECL) , 80mA (max, LVDS) • Output Logic : PECL or LVDS • Symmetry : 50% +/- 5% • Rise/Fall Time : 1.0 nSec (max) • RMS Phase Jitter : 1ps (max) • (12KHz ~ 20MHz) • Dimensions :7.0 x 5.0 x 1.9 (mm)

  10. Conclusion Out of Date ! The dual design are include a CMOS output crystal oscillator and a PECL or LVDS differential output IC. And it have poor jitter performance and higher current ,bigger dimensions in this design. Now, Taitien have a signal design for PECL or LVDS differential output of oscillator crystal. It is the trend in the future. We propose the signal product in your new design. And it will support good performance in your application.

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