Set-top Box Solutions
Satellite
Digital Satellite Dual Tuner RF IC
CX24128
Industry鈥檚 First Dual Tuner for DVR Applications
Conexant鈥檚 portfolio includes a comprehensive suite of semiconductor solutions for
broadband communications, enterprise networks and the digital home. The CX24128
is Conexant鈥檚 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.
Distinguishing Features
鈥?Dual stream RF-to-baseband
satellite receiver
PLL Dividers, Phase
Detector and Charge Pump
Variable Low
AGC
Pass Filter
Amplifier
VCO VCA
RF INPUT
A
90
0
I Channel
Output A
鈥?State-of-the-art architecture that
provides for up to 60 decibel (dB)
isolation between two channels
鈥?Zero-IF architecture eliminates the
need for image reject filtering
鈥?Very low phase noise for 8PSK and
DVB-S2 applications
鈥?Variable baseband filters for optimal
interference rejection
鈥?Auto-tuning machine eliminates need
for software calibration
鈥?Very low power consumption
Q Channel
Output A
Variable Low
AGC
Amplifier Pass Filter
VCA
RF INPUT
B
VCO
Reference
Oscillator
PLL Dividers, Phase
Detector and Charge Pump
Reference
to Demod
Programming
and Control
90
0
I Channel
Output B
Q Channel
Output B
鈥?Small (7 mm x 7 mm) footprint
鈥?Lead-free package
Part Number
CX24128
Description
Digital Satellite Dual Tuner RF IC
CX24128 Block Diagram
CONEXANT
1
2
