PL138-28 Datasheet, PDF (5/11 Pages) Micrel Semiconductor – 2.5V-3.3V Low-Skew 1-2 Differential PECL Fanout Buffer

PL138-28
2.5V-3.3V Low-Skew 1-2 Differential PECL Fanout Buffer
NOISE CHARACTERISTICS (Commercial and Industrial Temperature Devices)
Parameter
Description
Test Conditions
Min. Typ. Max. Unit
t_APJ Additive Phase Jitter
V DD=3.3V, Frequency=622.08MHz
Offset=12KHz ~ 20MHz
21
fs
REF Input PL138-28 Output
-60
-70
-80
-90
-100
-110
-120
-130
-140
-150
-160
100
1000
10000
100000
Offset Frequency (Hz)
1000000
10000000
100000000
When a buffer is used to pass a signal then the buffer will add a little bit of its own noise. The phase noise on the output of the
buffer will be a little bit more than the phase noise in the input signal. To quantify the noise addition in the buffer we compare the
Phase Jitter numbers from the input and the output. The difference is called "Additive Phase Jitter". The formula for the Additive
Phase Jitter is as follows:
2
2
Additive Phase Jitter = (Output Phase Jitter) - (Input Phase Jitter)
Micrel Inc. • 2180 Fortune Drive • San Jose, CA 95131 • USA • tel [phone] • fax [phone] • www.micrel.com Rev 11/26/13 Page 5