CX24128 Datasheet, PDF (1/2 Pages) Conexant Systems, Inc – Digital Satellite Dual Tuner RF IC

Set-top Box Solutions
Satellite
Digital Satellite Dual Tuner RF IC
CX24128
Industry’s First Dual Tuner for DVR Applications
Conexant’s portfolio includes a comprehensive suite of semiconductor solutions for
broadband communications, enterprise networks and the digital home. The CX24128
is Conexant’s innovative dual stream direct down-conversion satellite tuner RF IC
intended for high-volume digital video, audio, and data receivers. The CX24128 offers
excellent phase noise performance and very low implementation loss, required for
advanced modulation systems such as 8PSK and DVB-S2. The CX24128 provides
bill of materials (BOM) savings over two single tuners and simplifies layout for DVR
set-top boxes (STBs).
The CX24128 has a built-in auto-tuning machine that eliminates the need for software
calibration routine and accelerates the calibration time. The on-chip fractional
synthesizers enable fine frequency step size without adversely affecting lock time.
The CX24128 requires a single 3.3 V power supply and has an improved power
supply rejection ratio (PSRR) that reduces the need for power supply conditioning
components required for proper operation. The CX24128 does not require a Balun,
thus reducing external BOM cost. Its highly integrated design saves valuable board
space and simplifies RF layout.
RF INPUT
A
PLL Dividers, Phase
Detector and Charge Pump _{Variable Low}
AGC _{Pass Filter}
Amplifier
VCO _VCA
90
0
AGC ^{Variable Low}
Amplifier ^{Pass Filter}
RF INPUT
B
Reference
Oscillator
VCA
VCO
90
0
PLL Dividers, Phase
Detector and Charge Pump
Reference Programming
to Demod and Control
CX24128 Block Diagram
I Channel
Output A
Q Channel
Output A
I Channel
Output B
Q Channel
Output B
Distinguishing Features
• Dual stream RF-to-baseband
satellite receiver
• State-of-the-art architecture that
provides for up to 60 decibel (dB)
isolation between two channels
• Zero-IF architecture eliminates the
need for image reject filtering
• Very low phase noise for 8PSK and
DVB-S2 applications
• Variable baseband filters for optimal
interference rejection
• Auto-tuning machine eliminates need
for software calibration
• Very low power consumption
• Small (7 mm x 7 mm) footprint
• Lead-free package
Part Number CX24128
Description Digital Satellite Dual Tuner RF IC