Q-Tech SINE WAVE - Manual (Page 6)

6
Q-TECH Corporation - 10150 W. Jefferson Boulevard, Culver City 90232 - Tel: 310-836-7900 - Fax: 310-836-2157 - www.q-tech.com
SINE WAVE SOURCES
DUAL-IN-LINE CRYSTAL CLOCK OSCILLATORS
5.0 to 15Vdc - 10Hz to 450MHz
Q-TECH
CORPORATION
Sine Wave Sources (Revision E, August 2010 ) (ECO# 9936)
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 QT957S, +5Vdc, 150MHz and QT957S8M, +5Vdc, 69.4MHz clock at off-
set frequencies 10Hz to 10MHz, and phase jitter integrated over the bandwidth of 12kHz to 1MHz.
Phase Noise and Phase Jitter Integration
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.
QT957S, +5Vdc, 150MHz QT957S8M, 5.0Vdc, 69.4 MHz
Frequency vs. Temperature Curve
-50
-40
-30
-20
-10
0
10
20
30
40
50
-55 -50 -45 -40 -35 -30 -25 -20 -15 -10 -5 0 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95 100 105 110 115 120 125
Temperature (°C)
1_12 2_12
Frequency Stability (PPM)
FREQUENCY STABILITY VS. TEMPERATURE QT957S-64MHz