Figure 4-18: Magnitude (Db) Vs. Frequency (Hz) Response; For Eight Settings Of Rxfer[9:7] - Xilinx RocketIO X User Manual

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Chapter 4: Analog Design Considerations
Figure 4-18 is a plot of the magnitude frequency response for RXFER[9:7], while the other
7 bits are all 1s. RXFER[9:0] = XXX1111111.
The frequency steps in this case do not follow LSB to MSB. The order of lowest weight bit
to highest weight bit is RXFER[8], RXFER[9] then RXFER[7]. Hence, the boost of the
transfer function is set at low to high frequencies by the bits RXFER[9:7] = 000, 010, 100,
110, 001, 011, 101, and 111, respectively.
ug035_ch4_18b_111003

Figure 4-18: Magnitude (dB) vs. Frequency (Hz) Response

for Eight Settings of RXFER[9:7]

It can be easily observed from Figure 4-17 and Figure 4-18 that the magnitude vs.
frequency curves for RXFER[9:7] are very similar to those curves for RXFER[6:4]. They
represent two identical cascaded stages. Changing all six bits results in a cumulative
change in the boost frequency.
110 www.xilinx.com RocketIO™ X Transceiver User Guide
1-800-255-7778 UG035 (v1.5) November 22, 2004