SI4827-A10 Datasheet, PDF (14/25 Pages) Silicon Laboratories – BROADCAST ANALOG TUNING DIGITAL DISPLAY AM/FM/SW RADIO RECEIVER

Si4827-A10
4.2. FM Receiver
The Si4827-A10 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. The
FM band can also be configured to be wider range such
as 64–108 MHz in one band.
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 "AN602: Si4822/26/27/40/44 Antenna,
Schematic, Layout, and Design Guidelines."
4.3. AM Receiver
The highly integrated Si4827-A10 supports worldwide
AM band reception from 504 to 1750 kHz with five sub-
bands using a digital low-IF architecture with a minimum
number of external components and no manual
alignment required. This patented architecture allows
for high-precision filtering, offering excellent selectivity
and SNR with minimum variation across the AM band.
Similar to the FM receiver, the Si4827-A10 optimizes
sensitivity and rejection of strong interferers, allowing
better reception of weak stations.
To offer maximum flexibility, the receiver supports a
wide range of ferrite loop sticks from 180–450 μH. An
air loop antenna is supported by using a transformer to
increase the effective inductance from the air loop.
Using a 1:5 turn ratio inductor, the inductance is
increased by 25 times and easily supports all typical AM
air loop antennas, which generally vary between 10 and
20 μH.
A 9, 10 kHz tuning step can be chosen by the external
resistor or host MCU according to the different regions,
and AM soft mute level can be programmed by the host
MCU to have different tuning experiences. One of the
AM bands can be configured as a universal AM band
that simultaneously supports 9 kHz and 10 kHz channel
spaces for all regional AM standards. Refer to “AN610:
Si48xx ATDD Programming Guide” and "AN602:
Si4822/26/27/40/44 Antenna, Schematic, Layout, and
Design Guidelines" for more details.
4.4. SW Receiver
The Si4827 supports short wave band receptions from
2.3 to 28.5 MHz in 5 kHz step size increments. It can
also be configured to have wide SW band that can be
used in SW radio with 1 or 2 SW bands. The Si4827
supports extensive short wave features such as minimal
discrete components and no factory adjustments. The
Si4827 supports using the FM antenna to capture short
wave signals. Refer to “AN610: Si48xx ATDD
Programming Guide” and "AN602: Si4822/26/27/40/44
Antenna, Schematic, Layout, and Design Guidelines"
for more details.
4.5. Frequency Tuning
A valid channel can be found by tuning the
potentiometer that is connected to the TUNE1 and
TUNE2 pin of the Si4827-A10 chip.
To offer easy tuning, the Si4827-A10 also outputs the
tuned information to the MCU with LCD/LED driver to
display. It will light up the icon on display if the RF signal
quality passes a certain threshold when tuned to a valid
station. Refer to "AN610: Si48xx ATDD Programming
Guide" for more details.
4.6. Band Select
The Si4827-A10 supports worldwide AM band with five
sub-bands, US/Europe/Japan/China FM band with five
sub-bands, and SW band with 16 sub-bands. Si4827-
A10 provides the flexibility to configure the band and
band properties at either the MCU side or the tuner
side, enabling masked MCU for multiple projects. For
details on band selection, refer to "AN602:
Si4822/26/27/40/44 Antenna, Schematic, Layout, and
Design Guidelines" and "AN610: Si48xx ATDD
Programming Guide".
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Rev. 1.0