Receiver Circuit Testing

• Test setup• Eye diagrams• BER measurement• Eye - BER relationship• Evaluation Boards

Circuit Test Setup

• Pattern Generator• Attenuator• Oscilloscope

Signal Monitoring

• Terminated 50 coax for > 1 Mbps• capacitance (NRZ data, 50 ohms):

– 1/2piRC > data rate

RF Oscillation Prevention

• Grounded coax for all inputs• Single ground point for bias

RF Circuit Test

• 50 transmission line to chip:– Stripline printed circuit boards– or short lines

• 50 output drivers

BER Measurement

• PRBS source• Attenuation• Error measurement

PRBS

Atten

BER

PRBS source

20 40 60 80 100 120 140

0.5

0

0.5

FDDI code 274213IIJKTTBand Passed FDDI CodeZero Crossing

• Pseudo random data is severe test of receiver• Length of zero or one string is critical (ISI)• Eye diagram is “open” for low ISI

Attenuation

• Sensitivity of receiver:– BER over a range of input power (Pin) and data

rates• Dynamic range of transimpeadance Amp

(TIA) limits maximum input power – May need to reduce Pin to get normal operation

Error Measurement

• Correlate PRBS and output data• BER = number of errors / data bits

sent

• BER = 10-9 or 10-11 typical

• i.e., 1 error per Gbit of data = 10-9

40 35 30 251 1011

1 1010

1 109

1 108

1 107

1 106

1 105

1 104

BER is related toEye Diagram

• Vertical eye opening – Proportional to x in BER 10-x

– Practically only good to 10-8

MAX 3266 Evaluation Kit

• Hook your input into J1 and your Limiting Amplifier into J2 and J3 and your ready to test.

MAX3264 Evaluation Kit

Connect your TIA to J4 and J5 and J2 and J3 to your output and your ready to go. LOS threshold programming also done here.

Test of Eval Boards