CMOS Optical Preamplifier Design Using Graphical Circuit Analysis
CMOS Optical Preamplifier Design Using Graphical Circuit Analysis
CMOS Optical Preamplifier Design Using Graphical Circuit Analysis
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6.1 A 1V <strong>Optical</strong> Receiver Front-End 149<br />
Figure 6.14 Eye diagram of free-space optical link at 75 Mb/s with an<br />
input signal greater than 3µA.<br />
The on-chip analog multiplexor also allowed us to observe the eye diagrams at<br />
both the output of the first gain stage and the output of the preamplifier. Figure 6.16a<br />
shows the eye diagram of the preamplifier for a 3µA input signal. Although the eye<br />
is open, the eye diagram reveals a significant signal at high-frequencies. The band-<br />
width of the oscilloscope was 250MHz. To better gauge the actual eye diagram<br />
within the signal band, the output signals were filtered to 100MHz; the result is<br />
shown in Figure 6.16b. The eye diagram is clear as expected.<br />
Figure 6.15 Eye diagram from free-space optical link at 75 Mb/s with<br />
input signal of about 1µA.
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