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Feb 16th, 2020, 10:56pm
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questions about eye diagram of transimpedance amplifier (Read 489 times)
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questions about eye diagram of transimpedance amplifier
Aug 03rd, 2018, 3:19pm
hi i designed a transimpedance amplifier for 10 Gbps application with cadence virtuoso . i simulated eye diagram and it seems right but i have some questions about it .
1-in the book "Design of integrated circuits for optical communications" by behzad razavi says "optimal bandwidth is 0.7*rb that means 7 GHz for 10 Gbps and decreasing bandwidth reduces both vertical and horizontal eye opening" but for my circuit when bandwidth in process corners ss and tt decreases down to 4 and 5 GHz from 7.8 GHz nominal the vertical eye opening increases from 5.3 mv-pp to about 7 mv-pp and only horizontal eye opening decreases.why is that ?
2-the input current amplitude is 20 uA p-p in sonnet oc-192 standard and thats the amplitude of current random bits that i applied to my circuit and simulated eye diagram with. the transimpedance gain is 53.6 db ohm and that means i should have a 9.57 mv-pp output but the eye opening is 5.3 mv-pp and the difference between best "1" and best "0" is 12 mv-pp why ?
3- how much vertical eye opening is necessary for 10Gbps tia ? by what i read about eye diagrams and tia papers i think horizontal eye opening should be less than bit period is this true ? what should be the minimum and maximum of horizontal eye opening ?  if you answer any of my questions it would be really helpful . if you need BER its 10^-12
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