GX4002 Datasheet, PDF (20/74 Pages) Gennum Corporation – Dynamic on-chip power management control

When the equalization setting is 0dB, the equalization function is bypassed and the
receive sensitivity performance is the same as that of a limiting amplifier.
8dB
-6dB
14dB
Boost
7GHz
Figure 3-3: Channel 1 Equalization
3.3.3 Ch1 PLL Variable Loop Bandwidth
The loop bandwidth of the channel 1 Phase Locked Loops (PLLs) can be varied through
the digital control interface. The loop bandwidths are individually controlled, and can
cover a range of 1MHz to 23MHz through the following 5-bit registers:
Register Name
CH1PLL_REG1
CH1PLL_REG2
CH1PLL_REG9
Register
Address^d
20
21
28
Parameter Name
CH1PLLLBWCURVT
CH1PLLLBWCURVBE
CH1PLLLBWMULT
Bit
Position
Access
4:0
RW
4:0
RW
7:6
RW
Reset Value^b
10011
01110
10
Valid
Range^d
Function
0-31
Adjusts LBW positive temperature
coefficient control.
0-31
Adjusts LBW negative temperature
coefficient control.
0-3
LBW multiplier;
00 = 0.67, 10 = 1, 01 = 1.33, 11 = 1.67
The temperature coefficient of the loop bandwidth can be adjusted by a weighted
summation of CH1PLLLBWCURVT, which has a positive temperature coefficient, and
CH1PLLLBWCURVBE, which has a negative temperature coefficient. The default reset
values of the above registers produce an approximate loop bandwidth of 7MHz.
Table 3-4: Typical Loop Bandwidths for Various Register Settings
CH1PLLLBWMULT CH1PLLLBWCURVT CH1PLLLBWCURVBE
00
10 (default)
01
10011
10011
10011
01110
01110
01110
Loop
Bandwidth
4.6MHz
7.3MHz
9.9MHz
GX4002 2x2 14.025Gb/s Crosspoint Switch with Trace
Equalization and Output De-Emphasis
Data Sheet
55972 - 0
March 2012
20 of 74
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