AD9154 datasheet(35/124 Pages) AD

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Data Sheet

AD9154

Rev. C | Page 35 of 124

Equalization

To compensate for signal integrity distortions for each PHY

channel due to insertion loss caused by PCB trace characteristics,

the AD9154 employs an easy to use, low power equalizer on each

JESD204B channel. The AD9154 equalizers can compensate for

insertion losses far greater than required by the JESD204B

specification. The equalizers have two modes of operation

determined by the EQ_POWER_MODE register setting in

Bits[7:6] = 2b’01) and operating at the maximum lane rate, the

equalizer can compensate for up to 12 dB of insertion loss. In

normal mode (Register 0x268, Bits[7:6] = 2b’00), the equalizer can

compensate for up to 17.5 dB of insertion loss. This performance is

shown in Figure 44 as an overlay to the JESD204B specification for

insertion loss. Figure 44 shows the equalization performance at

10.0 Gbps, near the maximum baud rate for the AD9154.

Figure 45 and Figure 46 are provided as points of reference for

hardware designers and show the insertion loss for various

lengths of well laid out stripline and microstrip transmission

lines on FR-4 material.

Low power mode is recommended if the insertion loss of the

JESD204B PCB channels is less than that of the most lossy

supported channel for lower power mode (shown in Figure 44).

If the insertion loss is greater than that, but still less than that of

the most lossy supported channel for normal mode (shown in

Figure 44), use normal mode. At 10 Gbps operation, the equalizer

in normal mode consumes about 4 mW more power per lane

used than in low power equalizer mode. Note that either mode

can be used in conjunction with transmitter preemphasis to

ensure functionality and/or to optimize for power.

FREQUENCY (GHz)

5.0

7.5

2.5

AD9154 ALLOWED

CHANNEL LOSS

(NORMAL MODE)

AD9154 ALLOWED

CHANNEL LOSS

(LOW POWER MODE)

JESD204B SPEC ALLOWED

CHANNEL LOSS

EXAMPLE OF

JESD204B

COMPLIANT

CHANNEL

EXAMPLE OF

AD9154

COMPATIBLE

CHANNEL (LOW

POWER MODE)

EXAMPLE OF

AD9154

COMPATIBLE

CHANNEL

(NORMAL MODE)

Figure 44. Insertion Loss Allowed

–40

–35

–30

–25

–20

–15

–10

–5

FREQUENCY (GHz)

STRIPLINE = 6”

STRIPLINE = 10”

STRIPLINE = 15”

STRIPLINE = 20”

STRIPLINE = 25”

STRIPLINE = 30”

Figure 45. Insertion Loss of 50 Ω Striplines on FR-4

–40

–35

–30

–25

–20

–15

–10

–5

FREQUENCY (GHz)

6” MICROSTRIP

10” MICROSTRIP

15” MICROSTRIP

20” MICROSTRIP

25” MICROSTRIP

30” MICROSTRIP

Figure 46. Insertion Loss of 50 Ω Microstrips on FR-4

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