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 |
---|---|---|---|
VG-4501CA
CMOS output |
7.0×5.0×1.6t | optical networking and base station | |
VG-4513CA
LV-PECL output |
7.0×5.0×1.6t | optical networking and base station |
Basic Circuit Block Diagram
Configuration
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 122MHz |
VG-4513CA 122MHz |
---|---|---|
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 |
VG-4513CA 122.88MHz LV-PECL output |
---|---|---|
KV | 15.7KHz/V | 9.55KHz/V |
R2_A1 | 10K | 18K |
C1_A1 | 390nF | 220nF |
C2_A1 | 2700nF | 1000nF +470nF |
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
Materials
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 122.88/245.76/491.52MHz |
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 |
---|---|---|---|
VG-4513CA 122.88MHz LV-PECL |
91.9fsec | 93.7fsec | +1.8fsec |
VG-4501CA 122.88MHz CMOS |
92.4fsec | 92.1fsec | -0.3fsec |