MAX2108 Maxim, MAX2108 Datasheet - Page 9

• Manufacturer Part Number: MAX2108
• Description: Direct-Conversion Tuner IC
• Manufacturer: Maxim

Figure 2. Lowpass Filtering Example
PASSBAND FILTER REQUIREMENTS:
(1) <20% OF BAUD PERIOD DELAY RIPPLE
(2) <0.1dB GAIN RIPPLE
FOR POINTS 1, 2, 3, 4, REFER TO FIGURE 1
TRANSITION BAND FILTER REQUIREMENTS:
< 2dB GAIN RIPPLE
AT POINT
AT POINT
AT POINT
AT POINT
1
4
2
3
_______________________________________________________________________________________
dBc
dBc
dBc
dBc
-30
-30
-30
-30
0
0
0
0
0
0
0
DIGITAL MATCHED FILTER
DATA NYQUIST
CHANNEL
CHANNEL
(20Msps)
(20Msps)
DESIRED
DESIRED
LOWPASS FILTER RESPONSE
CHANNEL
CHANNEL
(20Msps)
(20Msps)
DESIRED
DESIRED
TRANSPONDER SPACING = 29.16 MHz
10
10
10
10 12
NYQUIST FOR ADC
12
12
12
= 0.2
Direct-Conversion Tuner IC
17.16
17.16
FOLDOVER
CHANNEL
17.16
ADJ
20
20
20
FILTER CUTOFF
ADC NYQUIST
UNDESIRED ADJACENT CHANNEL
28
TRANSPONDER BW = 24MHz
29.16
ADC SAMPLING
ADC SAMPLING
ADC SAMPLING
ADC SAMPLING
40
40 41.16
40
40
MHz
MHz
MHz
MHz
9