SI4836-A10 Datasheet, PDF (11/21 Pages) Silicon Laboratories – BROADCAST MECHANICAL TUNING AM/FM/SW RADIO RECEIVER

4. Functional Description
AM
ANT
FM
ANT
AMI
RFGND
FMI
LNA
AGC
0/90
XTALI
2.0~3.6V _VDD
AFC
REG
XTAL
OSC
Si4836-A10
Si4836
ADC
DAC
DSP
ADC
DAC
ADC
CONTROL INTERFACE
LOUT
ROUT
TUNE1/2
BAND
Figure 2. Si4836 Functional Block Diagram
4.1. Overview
The Si4836 is the high performance mechanical-tuned
digital CMOS AM/FM/SW radio receiver IC that
integrates the complete receiver function from antenna
input to audio output. The Si4836 extends Silicon
Laboratories multi-band tuner family, and further
increases the ease and attractiveness of design radio
reception to audio devices through small size and board
area, minimum component count, and superior, proven
performance. The Si4836 enhances the FM and SW
band coverage and further supports China TV channels
audio reception in FM band. The Si4836 removes any
requirements for manually tuning components during
the manufacturing process.
Leveraging Silicon Laboratories' proven and patented
digital low intermediate frequency (low-IF) receiver
architecture, the Si4836 delivers desired RF
performance and interference rejection in AM, FM, and
SW bands. The high integration and complete system
production test simplifies design-in, increases system
quality, and improves manufacturability.
4.2. FM Receiver
The Si4836 integrates a low noise amplifier (LNA)
supporting the worldwide FM broadcast band (64 to
109 MHz) and the TV audio stations within the
frequency range in China area are also supported.
Pre-emphasis and de-emphasis is a technique used by
FM broadcasters to improve the signal-to-noise ratio of
FM receivers by reducing the effects of high frequency
interference and noise. When the FM signal is
transmitted, a pre-emphasis filter is applied to
accentuate the high audio frequencies. All FM receivers
incorporate a de-emphasis filter which attenuates high
frequencies to restore a flat frequency response. Two
time constants are used in various regions. The de-
emphasis time constant can be chosen to be 50 or
75 µs. Refer to "AN738: Si4825/36-A Antenna,
Schematic, Layout, and Design Guidelines.”
The Si4836 also has advanced stereo blending that
employs adaptive noise suppression. As a signal quality
degrades, the Si4836 gradually combines the stereo left
and right audio channels to a mono audio signal to
maintain optimum sound fidelity under varying reception
conditions. The Si4836 can drive a stereo light with the
stereo/mono information so that the user can easily
Rev. 1.0
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