receiver circuit testing
DESCRIPTION
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. - PowerPoint PPT PresentationTRANSCRIPT
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