SX1231 SEMTECH [Semtech Corporation], SX1231 Datasheet - Page 64

• Manufacturer Part Number: SX1231
• Description: Low Power Integrated UHF Transceiver
• Manufacturer: SEMTECH [Semtech Corporation]

6.4. Receiver Registers
Table 24 Receiver Registers
Rev 2 - Nov 2009
ADVANCED COMMUNICATIONS & SENSING
Name
(Address)
RegAgcRef
(0x14)
RegAgcThresh1
(0x15)
RegAgcThresh2
(0x16)
RegAgcThresh3
(0x17)
RegLna
(0x18)
Bits Variable Name
5-0
7-5
4-0
7-4
3-0
7-4
3-0
5-3
2-0
7
6
7
6
-
AgcAutoReferenceOn
AgcReferenceLevel
AgcSnrMargin
AgcStep1
AgcStep2
AgcStep3
AgcStep4
AgcStep5
LnaZin
LnaLowPowerOn
LnaCurrentGain
LnaGainSelect
Mode
rw
rw
rw
rw
rw
rw
rw
rw
rw
rw
rw
r
r
Page 64
(-80dBm)
Default
000000
(16dB)
(11dB)
(11dB)
10000
Value
(5dB)
(7dB)
(9dB)
1011
1001
1011
0111
101
001
000
0
1
1
0
*
+10.log(2* RxBw ) + AgcSnrMargin , with:
Description
unused
To be set as close as possible to the receiver sensitivity
when AgcAutoReferenceOn = 0:
AGC Reference [dBm] = -80 - AgcReferenceLevel [dB]
SNR margin used in the receiver sensitivity calculation
when the AgcAutoReference = 1
Defines the first AGC Threshold:
AgcThresh1 = Agc Reference + AgcStep1
Defines the second AGC Threshold:
AgcThresh2 = AgcThresh1 + AgcStep2
Defines the third AGC Threshold:
AgcThresh3 = AgcThresh2 + AgcStep3
Defines the fourth AGC Threshold:
AgcThresh4 = AgcThresh3 + AgcStep4
Defines the fifth AGC Threshold:
AgcThresh5 = AgcThresh4 + AgcStep5
LNA’s input impedance
0
1
LNA and mixers low-power mode:
0
1
decreased
Current LNA gain, set either manually, or by the AGC
LNA gain setting:
000
001
010
011
100
101
110
111
0
1
AGC Reference [dBm] = -174 + NF + DemodSnr
- NF = 7: LNA’s Noise Figure at maximum gain
- DemodSnr = 8 dB, SNR needed by the demodulator
- AgcSnrMargin , as set in RegAgcThresh1
- RxBw : single sideband channel filter bandwidth
50 ohms
200 ohms
normal mode
low-power mode enabled. Power consumption is
AGC Reference is forced in AgcReferenceLevel
AGC Reference automatically computed by the chip:
reserved
G3 = highest gain – 12 dB
G6 = highest gain – 48 dB
gain set by the internal AGC loop
G1 = highest gain
G2 = highest gain – 6 dB
G4 = highest gain – 24 dB
G5 = highest gain – 36 dB
DATASHEET
www.semtech.com
SX1231