AT86RF212 Atmel Corporation, AT86RF212 Datasheet - Page 106

• Manufacturer Part Number: AT86RF212
• Manufacturer: Atmel Corporation

Specifications of AT86RF212

• Max. Operating Frequency: 0 MHz
• Crypto Engine: AES
• Operating Voltage (vcc): 1.8 to 3.6
• Frequency Band: 700/800/900MHz
• Max Data Rate (mb/s): 1
• Antenna Diversity: No
• External Pa Control: Yes
• Power Output (dbm): 10
• Receiver Sensitivity (dbm): -110
• Receive Current Consumption (ma): 9.0
• Transmit Current Consumption (ma): 18 at 5dBm
• Link Budget (dbm): 120

106
AT86RF212
Table 7-13. Register 0x05 (PHY_TX_PWR)
• Bit 7 – PA_BOOST
This bit enables the PA boost mode where the TX output power is increased by
approximately 5 dB when PA_BOOST = 1. In PA boost mode, the PA linearity is
decreased compared to the normal mode when PA_BOOST = 0. This leads to higher
spectral side lobes of the TX power spectrum and higher power of the harmonics.
Consequently, the higher TX power settings do not fulfill the regulatory requirements of
the European 868.3 MHz band regarding spurious emissions in adjacent frequency
bands (see ETSI EN 300 220-1, ERC/REC 70-03, and ERC/DEC/(01)04).
• Bit 6:5 – GC_PA
These register bits control the gain of the PA by changing its bias current. GC_PA
needs to be set in TRX_OFF mode only. It can be used to reduce the supply current in
TX mode when a reduced TX power is selected with the TX_PWR control word. A
reduced PA bias current causes lower RF gain and lowers the 1 dB- compression point
of the PA. Hence, it is advisable to use a reduced bias current of the PA only in
combination with lower values of TX_PWR. A reasonable combination of TX_PWR and
GC_PA is shown in Table 7-15.
Table 7-14. PA Gain Reduction Relative to the Gain at GC_PA=3
• Bit 4:0 – TX_PWR
These register bits control the transmitter output power. The value of TX_PWR
describes the power reduction relative to the maximum output power. The value
GC_TX = 0 provides the maximum output power. The resolution is 1 dB per step. Since
TX_PWR adjusts the gain in the TX path prior to the PA, the PA bias setting is not
optimal for increased values of TX_PWR regarding PA efficiency.
PA power efficiency can be improved when PA bias is reduced (decreased GC_PA
value) along with the TX power setting (increased TX_PWR value). A recommended
combination of TX power control (TX_PWR), PA bias control (GC_PA), and PA boost
mode (PA_BOOST) is listed in Table 7-15. It is a recommended mapping of intended
TX power to the 8-bit word in register 0x05. The value of TX_PWR shall be within the
range of 0 to 13 to guarantee the transmit signal quality.
Bit
Name
Read/Write
Reset Value
Bit
Name
Read/Write
Reset Value
Register Bits
GC_PA
7
PA_BOOST
R/W
0
3
TX_PWR[3]
R/W
0
Value
0
1
2
3
6
GC_PA[1]
R/W
1
2
TX_PWR[2]
R/W
0
5
GC_PA[0]
R/W
1
1
TX_PWR[1]
R/W
0
PA Gain [dB]
-2.9
-1.3
-0.9
0
8168C-MCU Wireless-02/10
4
TX_PWR[4]
R/W
0
0
TX_PWR[0]
R/W
0