MC44S803EP FREESCALE [Freescale Semiconductor, Inc], MC44S803EP Datasheet - Page 28

• Manufacturer Part Number: MC44S803EP
• Description: Low Power CMOS Broadband Tuner
• Manufacturer: FREESCALE [Freescale Semiconductor, Inc]

the signal level so that it is high enough for the tuner to be
directly connected to the demodulator. The output of Post
Amp 2 is routed off chip through the channel SAW and back
on chip to the second IF amplifiers. A switch is provided to
route the signal to either a digital or an analog demodulator
for settop box applications. The performance at the analog
and digital IF output ports are identical. The IF Amplifier gain
has some level of programmability. This is not intended for
Table 38. Second IF Amplifier Performance
MC44S803
28
Post Amplifier 2 Gain Settings
IF Amplifier Gain Settings
IF AGC Amplifier Gain at 0.5 V AGC
IF AGC Amplifier Gain at 3.3 V AGC
The Second IF consists of the on chip amplifiers that boost
Parameter
Mix 2
80
75
70
65
60
55
50
45
40
35
30
0
Figure 32. Tuner Gain versus IF AGC Voltage
Post
Amp 2
0.5
1
BPF
Figure 31. Second IF
SECOND IF
IF AGC Voltage (V)
1.5
IF Amp
Automatic Gain Control (AGC), but as a way to optimize the
gain distribution. It is envisioned that this gain would be fixed
at a certain level for the particular application. Since typical
analog demodulators have a high range of AGC control built
into them, the IF AGC control voltage will need to be fixed at
some level when using these demodulators. When using a
digital demodulator, the AGC control voltage is fed from the
digital demodulator. This is usually a filtered PWM signal.
2
2.5
IF AGC
Amp
6.0, 12, 18, or 20
3
6.0 or 8.3
Typ.
36
0
Output
Switch
3.5
Freescale Semiconductor
Unit
dB
dB
dB
dB