cx24118a NXP Semiconductors, cx24118a Datasheet - Page 15

• Manufacturer Part Number: cx24118a
• Description: Advanced Modulation Digital Satellite Tuner
• Manufacturer: NXP Semiconductors

2.1
Figure 2.
2.2
CX24118A_N_2
Product data sheet
CKREF_OUT
XTAL1
XTAL2
RF_IN
XSEL
AGC
General Description
Downconverter and Baseband Filtering
Detailed Block Diagram
Control
VCA
AGC
OUTRefDiv
The CX24118A is a highly integrated direct conversion tuner requiring a minimum of off-chip
components. It incorporates a low-noise amplifier with integrated Voltage Controlled
Attenuator (VCA), quadrature down converter, variable bandwidth base-band filter/amplifier,
fractional synthesizer, crystal oscillator with buffered output, and an automatic tuning system.
The chip is controlled through a multi-byte read/write enabled I
A CX24118A detailed block diagram is shown in
The L band input from the LNB is fed into the CX24118A either differentially or single-ended.
The input signal goes through a low-noise amplification block and is downconverted to a
baseband frequency by quadrature downconversion. The output of the downconverter is
band limited by a variable bandwidth filter that can be set to 35, 40, 65, or 100 MHz. A
CX24118A
Chapter 2: Functional Descriptions
Rev. 02 — 8 September 2009
0
1
Square Wave
Mixer
0
I/Q
o
90
Sine Wave
o
Filter 1
: 2
Rev. 02 — 8 September 2009
VGA1 Filter 2
PLLRefDiv
Cancellation
1
0
DC Offset
Cancellation
DC Offset
VGA2
PFD
Prescaler
18 Bit
DSM
Figure
LODivSel
Control
Final Amplifier
Filter
Charge
2.
Pump
: 2
2
Interface
C
:
:
Logic
®
2,
4
-compatible interface.
Product data sheet
VCO
© NXP B.V. 2009. All rights reserved.
I_OUT
Q_OUT
CP_OUT
VTUNE
SDA
SCL
SADD
102322_007
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