SI4824-DEMO Datasheet, PDF (11/20 Pages) List of Unclassifed Manufacturers – 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 _VDD1/2
AFC
REG
XTAL
OSC
Si4820/24-A10
Si4^S8ⁱ⁴3⁸²0⁰/^/23⁴4
ADC
DSP
DAC
AOUT
ADC
ADC
CONTROL INTERFACE
TUNE1/2
BAND
Figure 2. Si4820/24-A10 Functional Block Diagram
4.1. Overview
The Si4820/24-A10 is the entry level mechanical-tuned
digital CMOS AM/FM/SW radio receiver IC that
integrates the complete receiver function from antenna
input to audio output. The Si4820/24-A10 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 Si4820/24-A10 is drop-in replaceable
to the existing Si4831/35 tuner, requires a simple
application circuit, and removes any requirements for
manually tuning components during the manufacturing
process. It is a very simple product to design,
manufacture, and support across multiple product lines.
Leveraging Silicon Laboratories' proven and patented
digital low intermediate frequency (low-IF) receiver
architecture, the Si4820/24-A10 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 Si4820/24-A10 integrates a low noise amplifier
(LNA) supporting the worldwide FM broadcast band (64
to 109 MHz).
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.
Rev. 1.0
11