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

TAITIEN ELECTRONICS CO., LTD. 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.

TAITIEN ELECTRONICS CO., LTD. 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.

TAITIEN ELECTRONICS CO., LTD. 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.

TAITIEN ELECTRONICS CO., LTD. Signal Level Comparison V OH V OL V OH V OL V 4V 3V 2V 1V Supply Voltage PECLLVPECLLVDSCMOSTTL V OH_Min V OL_Max V OH V OL 90% VDD 10% VDD ECL V OH V OL Output Level

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 Out of Date Input Amplifier AC coupling Oscillator CMOS Output PECL or LVDS Output Q Q_Bar VDD Crystal Oscillator + Translator Buffers (Differential Output) CMOS Output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

TAITIEN ELECTRONICS CO., LTD. Single Design ! It is the Trend! PECL or LVDS Oscillator IC VDD PECL or LVDS Differential Output Crystal Oscillator Q Q_Bar Chipset PECL or LVDS Output

TAITIEN ELECTRONICS CO., LTD. Comparison of Design Design Dual Design Single Design Dimensions > Area (mm 2 ) 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

TAITIEN ELECTRONICS CO., LTD. PECL / LVDS Crystal Oscillator Specification OT Type Standard Frequency : 38.88, 62.5, 77.76, 100, , 125, , , , , , , 187.5, MHz Frequency Stability : +/- 50 ppm (+/-25 ppm,Available) Temp. Range :-20 o C ~ +70 o C (-40 o C ~ +85 o C, 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)

TAITIEN ELECTRONICS CO., LTD. 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.

TAITIEN ELECTRONICS CO., LTD.