Agilent Technologies N4962A Podręcznik Użytkownika Pobierz pdf (Strona 53)

Operation

Serial BERT 12.5 Gb/s User Guide 53

• Record the second phase value; the optimum point is halfway between

the two values

• Press the Adjust > Ø - button and adjust the phase offset to the

optimal point

• Observe the Error ε light (should remain off, indicating no errors

detected)

Depending on the DUT characteristics, the optimal sampling point may occur at

different detector phase adjustment values. You may need to repeat the phase

adjustment procedure when changing the DUT use characteristics, or if you

change the operating frequency.

4.7 Basic BER Measurement

The N4962A can quickly be used for basic BER measurements as follows:

connect the OUT/OUT¯¯¯ ports to the DUT input, connect the IN/IN¯¯ ports to the

DUT output, use the internal clock, power the system, enable the PRBS output,

adjust the detector clock phase, and turn on the error detector.

When connecting the OUT/OUT¯¯¯, and IN/IN¯¯ ports, use a short 50 Ω coaxial

cable. To test single-ended DUTs, terminate the OUT¯¯¯ and IN¯¯ ports with 50 Ω

terminations.

• Connect TX CKO to TX CKI with coaxial cable (included; default)

• Connect RX CKO to RX CKI with coaxial cable (included; default)

• Connect OUT to DUT input with short 50 Ω coax cable

• Optionally connect OUT¯¯¯to DUT input¯¯¯¯ with short phase-balanced 50 Ω

coax cable

• Connect DUT output to IN with short 50 Ω coax cable

• Optionally connect DUT output¯¯¯¯ to IN¯¯ with short phase-balanced 50 Ω

coax cable

Add appropriate attenuation or gain to DUT output, output¯¯¯¯ signals

• Terminate all unused RF connectors with 50 Ω terminations

• Turn on the power switch from the back panel

• Adjust the DUT for the best chance for error-free operation (turn

attenuators off, etc)

• Press the Data Path > Select Path button and select Enabled

• If the DUT is inverting, press the Data Path > PRBS¯¯¯¯ button to invert the

output

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Agilent Technologies N4962A Podręcznik Użytkownika Strona 53