VES1820X 데이터 시트보기 (PDF) - Philips Electronics
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VES1820X Datasheet PDF : 40 Pages
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Philips Semiconductors
Single chip DVB-C channel receiver
Product specification
VES1820X
PWMA
SELAGC
ADCSEL
FELPWM
æ Range ö
ç10 10240
ç
- 1÷.AGCREF
Bw è
=
RS
ø
213 +2.Kagc
where Range is the total AGC range in dB.
PWMA indicates the polarity of the VAGC output. When PWMA =1 (default) the
higher the DC level is, after low pass filtering on VAGC output, the lower the gain
must be. It is the opposite when PWMA=0.
SELAGC determines which kind of information is provided on output pin VAGC.
When SELAGC = 0 (default), VAGC is the PWM encoded AGC value. When
SELAGC = 1, VAGC is the sign of the amplitude error. (See FIGURE 11 and
FIGURE 12 page 16).
ADCSEL selects if the internal ADC is used (ADCSEL = 0) or if an external ADC is
used (ADCSEL = 1).
FELPWM determines the functionality of output pin FEL.
When FELPWM = 0 (default), FEL is a front end lock indicator.
When FELPWM = 1, FEL is a PWM encoded output, which value is programmed
in register PWMREF (index 3416).
4. CLKCONF
CLK_C
DYN
0316 READ/WRITE
CLK_C[2:0] must be set to 216.
DYN determines if the acquisition range for clock recovery is ± 120 ppm (DYN = 0,
default) or ± 240 ppm (DYN = 1).
GAIN2
GAIN2 allows to program the gain of the second decimation filter. When GAIN2 =
0 (default), the gain is 1 and when GAIN2 = 1, the gain is 2.
GAIN3
GAIN3 allows to program the gain of the third decimation filter. When GAIN3 = 0
the gain is 1 and when GAIN3 = 1 (default) the gain is 2.
NDEC[1:0] NDEC[1:0] determines the number of decimations according to the following table
Symbol Rate (SR)
SACLK/8 < SR < SACLK/4
SACLK/16 < SR < SACLK/8
SACLK/32 < SR < SACLK/16
SACLK/64 < SR < SACLK/32
NDEC[1 :0]
00 (0)
01 (1)
10 (2)
11 (3)
5. CARCONF
CAR_P[2]
0416 READ/WRITE
CAR_P[2] determines whether the carrier acquisition range is ± 2.5% of the
Symbol Rate (CAR_P[2]=0) or ± 8% (CAR_P[2]=1). Default is CAR_P[2]=0.
CAR_P[1:0] CAR_P[1:0] must be set to 116.
CAR_C[3:0] CAR_C[3:0] configures the coefficients of the carrier recovery loop filter, according
to the table below :
1999 March 01
21
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