AT86RF212B_14 Datasheet, PDF (14/212 Pages) ATMEL Corporation – Fully integrated 769 – 935MHz transceiver including

In this example, a balun (B1) transforms the differential RF signal at the
Atmel AT86RF212B radio transceiver RF pins (RFP/RFN) to a single ended RF signal,
similar to the Basic Application Schematic; refer to Figure 5-1. The RF switches (SW1,
SW2) separate between receive and transmit path in an external RF front-end. These
switches are controlled by the RX/TX Indicator, represented by the differential pin pair
DIG3/DIG4; refer to Section 11.4.
During receive, the corresponding microcontroller may search for the most reliable RF
signal path using an Antenna Diversity algorithm or stored statistic data of link signal
quality. One antenna is selected by an RF switch (SW2) controlled by pin 9 (DIG1)⁽¹⁾.
The RF signal is amplified by an optional low-noise amplifier (N2) and fed to the radio
transceiver using an RX/TX switch (SW1).
During transmit, the AT86RF212B TX signal is amplified using an external PA (N1), low
pass filtered to suppress spurious harmonics emission, and fed to the antennas via an
RF switch (SW2). In this example, RF switch SW2 further supports Antenna Diversity
controlled by pin 9 (DIG1)⁽¹⁾.
Note: 1. DIG1/DIG2 can be used as a differential pin pair to control an RF switch if RX
Frame Time Stamping is not used; refer to Section 11.3 and Section 11.5.
The Security Module (AES), Random Number Generator, Frame Buffer Empty
Indicator, Dynamic Frame Buffer Protection or Alternate Start-Of-Frame Delimiter do
not require specific circuitry to operate, for details refer to Section 11.1, Section 11.2,
Section 11.6, Section 11.7 and Section 11.8.
14 _AT86RF212B
42002C–MCU Wireless–08/13