SM1211E915 Semtech, SM1211E915 Datasheet - Page 18

• Manufacturer Part Number: SM1211E915
• Description: Dev Kit Accessory
• Manufacturer: Semtech

Specifications of SM1211E915

• Modulation Type: FSK, OOK
• Data Rate Max: 200Kbps
• Frequency Range: 902MHz To 928MHz
• Supply Voltage Range: 2.1V To 3.6V
• Module Interface: SPI
• Supply Current: 25mA
• Accessory Type: RF Module
• Sensitivity: -105dBm
• Operating Temperature (min): -40C
• Operating Temperature (max): 85C
• Operating Temperature Classification: Industrial
• Package Type: TQFN EP
• Operating Supply Voltage (min): 2.1V
• Operating Supply Voltage (typ): 2.5/3.3V
• Operating Supply Voltage (max): 3.6V
• Sensitivity (dbm): -105dBm
• Rohs Compliant: NA
• Lead Free Status / RoHS Status: na
• Lead Free Status / RoHS Status: na

The SX1211 is set to transmit mode when MCParam_Chip_mode = 100.
The baseband I and Q signals are digitally generated by a DDS whose digital to analog converters (DAC) followed
by two anti-aliasing low-pass filters transform the digital signal into analog in-phase (I) and quadrature (Q)
components whose frequency is the selected frequency deviation (Fdev).
In FSK mode, the relative phase of I and Q is switched by the input data between -90° and +90° with co ntinuous
phase. The modulation is therefore performed at this initial stage, since the information contained in the phase
difference will be converted into a frequency shift when the I and Q signals are up-converted in the first mixer
stage. This first up-conversion stage is duplicated to enhance image rejection. The FSK convention is such that:
Rev 7 – Sept 2
ADVANCED COMMUNICATIONS & SENSING
RFIO
3.3. Transmitter Description
3.3.1. Architecture Description
nd
, 2008
PA
Amplification
RF
up-conversion
Second
Figure 8: Transmitter Architecture
Q
I
DATA
DATA
Figure 9: I(t), Q(t) Overview
LO1 Tx
IF
First up-conversion
Page 18 of 92
'
' '
' ' 1 '
' ' 0
⇒
⇒
Q
Q
I
I
Fdev
Frf
1
Frf
LO2 Tx
LO2 Tx
Fdev
Fdev
Interpolation
filters
I(t)
Q(t)
Baseband
DACs
Waveform
generator
DDS
www.semtech.com
SX1211
Data
Clock