cxa3235n Sony Electronics, cxa3235n Datasheet - Page 9

• Manufacturer Part Number: cxa3235n
• Description: All Band Tv Tuner Ic With On-chip Pll - Sony Corporation
• Manufacturer: Sony Electronics

Description of Functions
1. Mixer circuit
2. Local oscillator circuit
3. IF amplifier circuit
4. PLL circuit
The CXA3235/3236N is a terrestrial wave broadcast tuner IC which converts frequencies to IF in order to
tune and detect only the desired reception frequency of VHF, CATV and UHF band signals.
In addition to the mixer, local oscillator and IF amplifier circuits required for frequency conversion to IF, this
IC also integrates a PLL circuit for local oscillator frequency control onto a single chip.
The functions of the various circuits are described below.
This circuit outputs the frequency difference between the signal input to VHFIN or UHFIN and the local
oscillation signal.
A VCO is formed by externally connecting an LC resonance circuit composed of a varicap diode and
inductance.
This circuit amplifies the mixer IF output, and consists of an amplifier stage and low impedance output
stage.
This PLL circuit fixes the local oscillator frequency to the desired frequency. It consists of a prescaler, main
divider, reference divider, phase comparator, charge pump and reference oscillator. The control format
supports the I
frequency division values of the main and reference dividers.
Mode
2
B-0
B-1
B-2
B-3
B-4
C bus format. The following five modes can be selected according to the combination of the
Main divider
15 bit
14 bit
15 bit
15 bit
15 bit
—9—
512/1024 switching
Reference divider
1024 fixed
512 fixed
640 fixed
512 fixed
CXA3235/3236N