AT86RF233_14 Datasheet, PDF (13/225 Pages) ATMEL Corporation – Low Power, 2.4GHz Transceiver for ZigBee, RF4CE, IEEE

4 General Circuit Description
The Atmel AT86RF233 single-chip radio transceiver provides a complete radio
transceiver interface between an antenna and a microcontroller. It comprises the analog
radio, digital modulation and demodulation including time and frequency
synchronization, as well as data buffering. A single 128-byte TRX buffer stores receive
or transmit data. Communication between transmitter and receiver is based on direct
sequence spread spectrum with different modulation schemes and spreading codes.
The AT86RF233 block diagram is shown in Figure 4-1.
Figure 4-1. AT86RF233 Block Diagram.
DIG3/4
ext. PA and Power
Control
XOSC AVREG
Configuration Registers
PA
PLL
TX Data
TX BBP DVREG
SPI
RFP
(Slave)
FTN, BATMON
Frame
Buffer
RFN
LNA
PPF
BPF
Limiter
ADC
RX BBP
AES
DIG1/2
AD
Analog Domain
AGC
Antenna Diversity
RSSI
Control Logic
Digital Domain
/SEL
MISO
MOSI
SCLK
IRQ
CLKM
DIG2
/RST
SLP_TR
The number of external components is minimized such that only the antenna, the
crystal and decoupling capacitors are required. The bidirectional differential antenna
pins (RFP, RFN) are used for transmission and reception, thus no external antenna
switch is needed. Control of an external power amplifier is supported by two digital
control signals (differential operation).
The received RF signal at pin 5 (RFN) and pin 6 (RFP) is differentially fed through the
low-noise amplifier (LNA) to the RF filter (PPF) to generate a complex signal, driving the
integrated channel filter (BPF). The limiting amplifier provides sufficient gain to drive the
succeeding analog-to-digital converter (ADC) and generates a digital RSSI signal. The
ADC output signal is sampled by the digital base band receiver (RX BBP).
The transmit modulation scheme is offset-QPSK (O-QPSK) with half-sine pulse shaping
and 32-length block coding (spreading) according to [1], [2] and [3]. The modulation
signal is generated in the digital transmitter (TX BBP) and applied to the fractional-N
frequency synthesis (PLL), to ensure the coherent phase modulation required for
MCU Wireless AT86RF233 [PRELIMINARY DATASHEET] ¹³
Atmel-8351E-MCU_Wireless-AT86RF233_Datasheet_072014