For customers designing Texas Instruments
Ultra Low Jitter Synthesizer and Jitter Cleaner "LMK04828B"

EPSON VCXO matching trial for Texas Instruments Jitter Cleaner LMK04828B
Comparison with Texas Instruments simulator (National Clock Design Tool) and measurement data.

Matching Results

The simulation results matched the measured data well.
As conclusion, VCXOs (VG-4513CA,VG4501CA) have good performance with TI LMK04828B.
For more information, please see the following:

Epson Crystal Product Lineups

Product Size[mm]Applications Images
CMOS output
7.0×5.0×1.6t optical networking and base station
LV-PECL output
7.0×5.0×1.6t optical networking and base station

Basic Circuit Block Diagram


TI LMK04828B Jitter Cleaner(Dual PLL typ.)

LMK04828 Configuration PLL1

VCXO parameter (measured data)

PLL1 Loop Filter - before adjustment (original Value)

VCXO frequency VG-4501CA
KV 15.7KHz/V 9.55KHz/V
lcp 15.7KHz/V 9.55KHz/V
LOOP BW 40.564Hz 28.265Hz
Phase Margin 40.673degrees 46.888degrees
Gamma Optimaztion Factor 5.857 2.844
Natural Frequency 17.851Hz 13.922Hz
Damping Factor 1.487 1.16

PLL1 Loop Filter adjustment for EPSON VCXOs

Components VG-4501CA
122.88MHz CMOS output
122.88MHz LV-PECL output
KV 15.7KHz/V 9.55KHz/V
R2_A1 10K 18K
C1_A1 390nF 220nF
C2_A1 2700nF 1000nF
I ChargePump 100uA 100uA
LOOP BW 14.148Hz 15.195Hz
Phase Margin 50.5degrees 50.2degrees

Adjust Res and Cap value.

LMK04828B Configuration PLL2

PLL2 Loop Filter

Evaboard default value – no change

C1_A2 0.047nF Evaboard original
C2_A2 3.9nF Evaboard original
C3 Internal 10pF minimum
C4 Internal 10pF minimum
R2_A2 0.62Kohm Evaboard original
R3 Internal 0.2Kohm minimum
R4 Internal 0.2Kohm minimum
I ChargePump 3200uA maximum

PLL2 Loop Filter Characteristics

VCXO frequency 122MHz R=1 N=8
KV 18.3734MHz/V
LOOP BW 245.515KHz
Phase Margin 70.86degrees
Gamma Optimaztion Factor 0.269
Natural Frequency 0.2Kohm
R4 Internal 125.07KHz
Damping Factor 0.95

PLL2 Bode Plot PFD2=122.88MHz

Output Setup


Evaluation Board LMK04828BEVAL 1pcs
OCXO OX-6501GG 30.72MHz
ESC Signal Generator E4438C 30.72MHz
FM Noise Mod
Power Supply 5V E363A and othwes
VCXO1 VG-4513CA Epson
VCXO2 VG4501CA Epson
122.88MHz CMOS
PC Thinkpad X32 WindowsXP
Chip Control Application CodeLoader4 Version4.7.5
Part File v1.8.5
Simulator NCDT Clock Disign Tool Version1.3.5

Simulation Results

CN curve w/VG-4513CA 122MHz -> 245MHz OUT

CN curve w/VG-4513CA 245MHz -> 245MHz OUT

CN curve w/VG-4501CA 122MHz -> 245MHz OUT

Phase jitter w/VG-4501CA 122MHz -> 245MHz OUT

Comparison Results - Simulator vs Measurement

Phase jitter results

VCXO simulation Measured value Difference
122.88MHz LV-PECL
91.9fsec 93.7fsec +1.8fsec
122.88MHz CMOS
92.4fsec 92.1fsec -0.3fsec

PLL OUT 245.76MHz / VG-4513CA 122.88MHz

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