RDA5820 Ver la hoja de datos (PDF) - Unspecified

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RDA5820

SINGLE-CHIP BROADCAST FM TRANSCEIVER

Unspecified 

RDA Microelectronics, Inc.

3 Functional Description

RDA5820 FM Transceiver V1.3

Figure 3-1. RDA5820 FM Transceiver Block Diagram

3.1 FM Transceiver Structure

The RDA5820 is a single-chip FM transceiver

(Rx/Tx). Based on RDA patented dual

synthesizers RF structure, it has perfectly FM

receive and transmit performances, also least

external components. The RDA5820 integrate 4K

memory, this make it have additional advantage

such as saving frequency or datas.

Except FM receive and transmit, the RDA5820

also have I2S input/output, audio amplify,

integrated PCB antenna functions. All these make

it very suitable for portable devices.

3.2 FM Receiver

The receiver uses a digital low-IF architecture that

avoids the difficulties associated with direct

conversion while delivering lower solution cost

and reduces complexity, and integrates a low

noise amplifier (LNA) supporting the FM

broadcast band (65 to 115MHz), a quadrature

image-reject mixer, a programmable gain control

(PGA), a high resolution analog-to-digital

converters (ADCs), an audio DSP and a high-

fidelity digital-to-analog converters (DACs).

The LNA has differential input ports, one for usual

FM antenna, and the other port connect with

FMOUT port, which support integrated PCB

antenna (small antenna). The two LNA ports can

be arbitrary selected by set according registers

bits (LNA_PORT_SEL[1:0]). It default input

common mode voltage is GND.

The quadrature mixer down converts the LNA

output differential RF signal to low-IF, it also has

image-reject function.

The PGA amplifies the mixer output IF signal and

then digitized with ADCs.

The DSP core finishes the channel selection, FM

demodulation, stereo MPX decoder and output

audio signal. The MPX decoder can autonomous

switch from stereo to mono to limit the output

noise.

The DACs convert digital audio signal to analog

and change the volume at same time. The DACs

has low-pass feature and -3dB frequency is about

30 KHz.

The PA (Power Amplifier) is power down. Its

output impedance is high resistance.

If use integrated PCB antenna (small antenna),

the FM signal input from FMOUT port. C_VAR is

autonomous tune when setting different receive

frequency.

The information contained herein is the exclusive property of RDA and shall not be distributed, reproduced, or disclosed in whole or in

part without prior written permission of RDA.

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