L64780 LSI Logic Corporation, L64780 Datasheet - Page 23

• Manufacturer Part Number: L64780
• Description: Dvb-t Cofdm Demodulator Technical Manual 2/00
• Manufacturer: LSI Logic Corporation

2.3.2 AGC External Loop Filter
Since the recommended RMS value is
value is
(0b0111.0100). Thus:
Also see the description in
page
The input power control signal drives the Sigma Delta modulated output,
AGCOUT. Use the AGCOUT signal to drive an external passive RC filter
that feeds the gain control stage, as shown in
Figure 2.3
AGCOUT
The R and C values for the low-pass filter must meet the following
requirement:
Equation 2.2
See
Automatic Gain Control (AGC)
AGC_TARGET_LSB = 0x4 (0b100)
AGC_TARGET_MSB = 0x0E (0b01110)
Figure 2.3
4-23.
=
AGC Loop Pass Filter
5V
0.226
R
for the recommended values.
R= 5.6 k
AGC
, resulting in an AGC_TARGET initial value of 0x74
C
AGC
Section 4.4.4, “Address Line 0x0A,”
R
= 560 s
AGC
= 56 k
=
C
AGC
0.283
= 10 nF
Figure
, the recommended
2.3.
2-5
T