SI4831-B30-GU Datasheet, PDF (10/20 Pages) Silicon Laboratories – BROADCAST MECHANICAL TUNING AM/FM/SW RADIO RECEIVER

Si4831/35-B30
4. Functional Description
AM
ANT
FM/SW
ANT
AMI
RFGND
FMI
LNA
AGC
0/90
XTALI
2.0~3.6V _VDD1/2
AFC
REG
XTAL
OSC
S^Si4ⁱ⁴8⁸3³0^1//³3⁵4
ADC
DAC
LOUT
DSP
ADC
DAC
ROUT
ADC
CONTROL
INTERFACE
TUNE 1/2
BAND
Figure 2. Si4831/35-B30 Functional Block Diagram
4.1. Overview
The Si4831/35-B30 is the industry's most advanced
fully integrated, mechanical-tuned 100% CMOS
AM/FM/SW radio receiver IC. Offering unmatched
integration and PCB space savings, the Si4831/35-B30
requires minimum external components and a small
board area. The Si4831/35-B30 AM/FM/SW radio
provides space savings and low power consumption
while delivering the high performance and design
simplicity desired for all AM/FM/SW solutions.
Leveraging Silicon Laboratories' proven and patented
digital low intermediate frequency (low-IF) receiver
architecture, the Si4831/35-B30 delivers superior 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 Si4831/35-B30 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. Refer to "AN555: Si483x-B Antenna, Schematic,
Layout, and Design Guidelines."
The Si4831/35-B30 also has advanced stereo blending
that employs adaptive noise suppression. As a signal
quality degrades, the Si4831/35-B30 gradually
combines the stereo left and right audio channels to a
mono audio signal to maintain optimum sound fidelity
under varying reception conditions. The Si4831/35-B30
can drive a stereo light with the stereo/mono information
so that the user can easily discern the signal quality.
10
Rev. 1.0