Q-Tech QT84 - Manual (Page 6)

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Q-TECH Corporation - 10150 W. Jefferson Boulevard, Culver City 90232 - Tel: 310-836-7900 - Fax: 310-836-2157 - www.q-tech.com
LOW PROFILE QT84
MINIATURE SMD CRYSTAL OSCILLATORS
1.8 to 5.0Vdc - 500kHz to 160MHz
Q-TECH
CORPORATION
QPDS-0003, Rev G, February 2013 (ECO# 10720)
Phase noise is measured in the frequency domain, and is expressed as a ratio of signal power to noise power measured in a 1Hz bandwidth
at an offset frequency from the carrier, e.g. 10Hz, 100Hz, 1kHz, 10kHz, 100kHz, etc. Phase noise measurement is made with an Agilent
E5052A Signal Source Analyzer (SSA) with built-in outstanding low-noise DC power supply source. The DC source is floated from the
ground and isolated from external noise to ensure accuracy and repeatability.
In order to determine the total noise power over a certain frequency range (bandwidth), the time domain must be analyzed in the frequency
domain, and then reconstructed in the time domain into an rms value with the unwanted frequencies excluded. This may be done by
converting L(f) back to Sφ(f) over the bandwidth of interest, integrating and performing some calculations.
The value of RMS jitter over the bandwidth of interest, e.g. 10kHz to 20MHz, 10Hz to 20MHz, represents 1 standard deviation of phase
jitter contributed by the noise in that defined bandwidth.
Figure below shows a typical Phase Noise/Phase jitter of a QT84L11, 3.3Vdc, 106.25MHz clock at offset frequencies 10Hz to 1MHz,
and phase jitter integrated over the bandwidth of 12kHz to 1MHz.
Phase Noise and Phase Jitter Integration
QT84L11, 3.3Vdc, 106.25MHz
Symbol Definition
∫L(f) Integrated single side band phase noise (dBc)
Sφ (f)=(180/Π)x √ 2 ∫L(f)df Spectral density of phase modulation, also known as RMS phase error (in degrees)
RMS jitter = Sφ (f)/(fosc.360°) Jitter(in seconds) due to phase noise. Note Sφ (f) in degrees.
ECO REV REVISION SUMMARY Page
10452 E
Change date code marking format to YYWW (year/week)
3
Corrected landing pattern dimensions
10623 F
Add Solder Dip option G 1
Modified Package Material From 90% AL2O3 to 91% AL2O3 3
10720 G
Features: Modified 36000G shock to half sine, 0.5ms
1
Ordering Information: Added Frequency vs. Temperature code 17 & 18
Change Rise and Fall Time from 30MHz to 40MHz 2
Revision History