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BER Tester with Jitter Injection for Stressed Eye Testing

The N4962A serial BERT 12.5 Gb/s also has the capability to inject jitter

onto the output PRBS datastream; an important component of IEEE-specified

stressed eye tests. This is accomplished by applying an external signal to the

JitterI input port as illustrated in Figure 8.

Oscilloscope

LF TrigO

HF TrigO

JitterI

EXT CKI

TX CKO

~IN

~OUT

OUT

DUT

Function

generator

RX CKI

RX CKO

TX CKI

N4962A serial BERT

12.5 Gb/s

Precision

trigger

input

Data

input

Figure 8. Block diagram – BER measurement with jitter injection for stressed eye testing

The function generator generates the signal that the BERT FM modulates onto

the full-rate clock. This is typically a sinusoid, but the JitterI input could be

a square wave, a Gaussian noise source, and even an uncorrelated PRBS bit

stream.

The JitterI input bandwidth is DC to 100 MHz; the N4962A serial BERT

12.5 Gb/s User Guide spells out the amount of UI that can be injected in

Section 2.2. The UI injection vector is also supplied, relating the input voltage

to UI of jitter injected.

The jitter is applied to the TX CKO and HF TrigO outputs. The RX CKO and LF

TrigO outputs are not jittered. The JitterI input requirements range from 0 to 2 V.

Consult the BERT User Guide for detailed procedures regarding the use of the

jitter injection feature: change the jitter option to 1.

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Agilent Technologies N4962A Betriebsanweisung Seite 7