18

Am79761

PRELIMINARY

MEASUREMENTS (Continued)

Figure 25.

Transmitter Jitter Measurement Method

BERT

Pattern

Generator

CLK = 1.25 GHz

DATA = 00000 0000011111 11111

DATA

PAT SYNC

Am79761

TXD[0:9]

REFCLK

TX+

TX-

Digitizing

Scope

Trigger

1.25 Gbps

Single-Ended Measurement

125 MHz

125 MHz

TRIGGER

DATA

2 bit time

7 bit time

8 bit time

9 bit time

12 bit time

17 bit time

19 bit time

20 bit time

18 bit time

10 bit time

BERT

Pattern

Generator

CLK = 1.25 GHz

DATA = 00000 0000011111 11111

DATA

DATA

Am79761

TXD[0:9]

REFCLK

TX+

TX-

Digitizing

Scope

Trigger

1.25 Gbps

Single-Ended Measurement

125 MHz

125 MHz

RJ

-K28.7

0011111000

Random Jitter Measurement

Random jitter (RJ) measurements performed according to Fibre Channel 4.3 Annex A, Test Methods, Section

A.4.4. Measure standard deviation of all 50% crossing points. Peak to peak RJ is

±7 sigma of distribution.

Deterministic Jitter Measurement

Deterministic jitter (DJ) measurements

performed according to Fibre Channel

4.3 Annex A, Test Methods, Section A.4.3.

Measure time of all the 50% points of

all ten transitions. DJ is the range of

the timing variation from expected.

-K28.7

0011111000

DJ

-K28.5

0011111010

K28.5

1100000101

21560A-11

Transmitter Output Jitter Allocation

Serial data output random jitter

(RMS)

RMS, tested on a sample basis

(refer to Figure 8)

—20

ps

Serial data output deterministic

jitter (p-p)

Peak to peak, tested on a sample

basis (refer to Figure 8)

—

100

ps