GDC21D003 Datasheet, PDF (58/77 Pages) Hynix Semiconductor – VSB Receiver

GDC21D003
6.5.4 I2C Bus I/F
User can initialize the resulting phase tracking
value through I2C register33[6] (InitPHI2) bit.
There are three loops in phase tracker; gain
correction loop, offset correction loop, and phase
correction loop. The following table shows
contents of register address 33 and these three
loops can be turned on/off through this
register[5:4] (PHASmodeIN). The mean squared
errors are calculated at phase tracker output and
can be read using I²C bus through MeanErrOUTPH.
Table 6.5.1 Contents of I²C Bus Register33 for Phase Tracker
7
nFreezePHI2
6
InitPHI2
[5:4]
PHASmodeIN
[1:0]
‘0’ : Freezes the Phase Tracker in the device, which means phase tracking does
not occur.
W/R ‘1’ : normal operation
If you want to control Phase Tracker fast, use external input pins.
Default value is ‘1’.
‘1’ : Initializes the Phase Tracker in the device.
W/R
‘0’ : normal operation
If you want to control Phase Tracker fast, use external input pins.
Default value is ‘0’.
There are three loops in the Phase Tracker, gain, offset, and phase loop.
00 : all loops on
W/R
01 : offset loop off
10 : offset and gain loops off
11 : all loops off
Default value is “00”.
There are 4 different modes for phase tracking gain
control as seen in the table 6.5.2. There is a trade-
off relation between gain and noise enhancement in
phase tracker. So the phase tracker in this device
changes the gain according to the noise condition.
As shown in table, if LOOPgainIN is set to “000”
gain is changed automatically according to the
noise condition. This means that this routine has
noise calculator and selects a gain by using the
calculated noise information. User can also control
the gain of phase tracker by setting to “001”, “010”,
or “011”. The default is “000” with this automatic
gain mode.
Table 6.5.2 Contents of I²C Bus Register36 for Gain Control
[5:3]
LOOPgainIN
[2 : 0]
Determines the use of automatic gain routine and the type of loop gain used in
Phase Tracker. Default value is “000”.
“000” : Automatic gain change.
W/R “001” : phase tracker is OFF.
“010” : smaller gain.
“011” : normal gain.
“1xx” : not use.
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