GDC21D003 Datasheet, PDF (55/77 Pages) Hynix Semiconductor – VSB Receiver

6.4.7 Coefficient Reading/Writing
The adaptive filter is able to initialize and freeze its
coefficients as well as download the coefficients
through I²C register by user. The following are
coefficient reading/writing routines through I²C
register, and the I²C control block in figure 6.4.6
supports this coefficient reading/writing function
Equalizer / Phase Tracker Coefficient Write
Routine
1) Freeze an equalizer and a phase tracker.
(Sets nFreezeEQI2 and nFreezePHI2 to ‘0’)
2) Sets the nCoefRead to a write mode.
(set this bit to ‘1’)
3) Writes the filter tap address to write the
coefficients.(TapAddress : Register37)
4) Write the coefficients.
(WrCoef : Register38, 39)
5) Sets the nMakeRingIN to ‘0’.
6) Sets the nMakeRingIN to ‘1’.
7) To write another coefficients, goes to the 3^rd step.
8) Sets nFreezeEQI2 and nFreezePHI2 to HIGH
and quits the write routine.
Equalizer Coefficient Read Routine
1) Freeze an equalizer and a phase tracker.
(Sets nFreezeEQI2 and nFreezePHI2 to ‘0’)
2) Set the nCoefRead to a read mode.
(Set this bit to ‘0’)
3) Writes the filter tap address to read the
coefficients. (TapAddress : Register37)
4) Set the nMakeRingIN to ‘0’.
GDC21D003
5) Read the coefficients.(RdCoef : Register38, 40)
6) Set the nMakeRingIN to ‘1’.
7) To read another coefficients, goes to the 3^rd step.
8) Set nFreezeEQI2 and nFreezePHI2 to HIGH and
quit the read routine.
6.5 Phase Tracker
The Phase Tracker corrects the untracked phase
noise in the receiver. It uses slice prediction
information that comes from the Viterbi Decoder
so that this phase tracker increases its performance
in severe noise environment. There are three loops;
gain correction loop, offset correction loop, and
phase correction loop. Phase Error Correction
block corrects the distortion caused by a phase
noise using an estimated error in the output of the
Phase Tracker.
User can control the gain of Phase Tracker by using
I²C register. There is a trade-off relation between
gain and noise enhancement in phase tracker. So
the phase tracker in this device change the gain
according to the noise condition. To increase the
performance the phase tracker is using the slice
predict information that comes from viterbi
decoder. Phase tracking range is -60° ~ 60° with
resolution of 0.004°. This means that phase error
estimation part can estimate phase error degree
with 0.004° resolution and phase tracker can track
the phase noise from -60° to 60° successfully. A
block diagram of the Phase Tracker is shown in
Figure 6.5.1.
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