14.4.3.1 Overview

The AT86RF212B transmitter utilizes a direct up-conversion topology. The digital transmitter (TX BBP) generates the in-phase (I) and quadrature (Q) component of the modulation signal. A digital-to-analog converter (DAC) forms the analog modulation signal. A quadrature mixer pair converts the analog modulation signal to the RF domain. The power amplifier (PA) provides signal power delivered to the differential antenna pins (RFP, RFN). Both, the LNA of the receiver input and the PA of the transmitter output are internally connected to the bidirectional differential antenna pins so that no external antenna switch is needed.

Using the default settings, the PA incorporates an equalizer to improve its linearity. The enhanced linearity keeps the spectral side lobes of the transmit spectrum low in order to meet the requirements of the European 868.3MHz band.

If the PA boost mode is turned on, the equalizer is disabled. This allows to deliver a higher transmit power of up to +11dBm at the cost of higher spectral side lobes and higher harmonic power.

In Basic Operating Mode, a transmission is started from PLL_ON state by either writing TX_START to the TRX_CMD bits in the TRX_STATE regoster (TRX_STATE.TRX_CMD) or by a rising edge of pin 11 (SLP_TR).

In Extended Operating Modes, a transmission might be started automatically depending on the transaction phase of either RX_AACK or TX_ARET.