Receiver Circuit Testing
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Transcript of Receiver Circuit Testing
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Receiver Circuit Testing
• Test setup• Eye diagrams• BER measurement• Eye - BER relationship• Evaluation Boards
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Circuit Test Setup
• Pattern Generator• Attenuator• Oscilloscope
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Signal Monitoring
• Terminated 50 coax for > 1 Mbps• capacitance (NRZ data, 50 ohms):
– 1/2piRC > data rate
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RF Oscillation Prevention
• Grounded coax for all inputs• Single ground point for bias
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RF Circuit Test
• 50 transmission line to chip:– Stripline printed circuit boards– or short lines
• 50 output drivers
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BER Measurement
• PRBS source• Attenuation• Error measurement
PRBS
Atten
BER
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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
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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
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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
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BER is related toEye Diagram
• Vertical eye opening – Proportional to x in BER 10-x
– Practically only good to 10-8
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MAX 3266 Evaluation Kit
• Hook your input into J1 and your Limiting Amplifier into J2 and J3 and your ready to test.
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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.
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Test of Eval Boards