RFM66W Datasheet, PDF (27/87 Pages) List of Unclassifed Manufacturers – 868 & 915MHz Ultra Low Power High Link Budget Integrated UHF Transceiver

WIRELESS & SENSING
RFM66W
DATASHEET
3.5. Receiver Description
3.5.1. Overview
The RFM66W features a digital receiver with the analog to digital conversion process being performed directly following
the LNA-Mixers block. The Low-IF receiver is able to handle ASK, OOK, (G)FSK and (G)MSK modulation. All the filtering,
demodulation, gain control, synchronization and packet handling is performed digitally, which allows a very wide range of
bit rates and frequency deviations to be selected. The receiver is also capable of automatic gain calibration to improve
precision on RSSI measurement and enhanced image rejection.
Figure 8. Receiver Block Diagram
3.5.2. Automatic Gain Control - AGC
The AGC feature allows receiver to handle a wide Rx input dynamic range from the sensitivity level up to maximum input
level of 0dBm or more, whilst optimizing the system linearity.
The automatic LNA gain control is effective by setting the bit AgcAutoOn to '1'. The automatic adjustment of the LNA gain
can be perform on the Rx input level (Pin) at receiver start up and/or during the Preamble reception. The automatic
adjustment of the LNA during the Preamble is effective by setting the bit AgcOnPreamble to '1' otherwise it will be
performed only at the receiver start up.
The LNA gain can also be manually selected using LnaGain bits and by disabling the automatic LNA gain control by setting
the AgcAutoOn bit to '0'.
Table 15 hereafter shows typical NF and IIP3 performances for the different LNA gains.
Table 15 LNA Gain Control and Performances
RX input level (Pin)
Pin <= AgcThresh1
AgcThresh1 < Pin <= AgcThresh2
AgcThresh2 < Pin <= AgcThresh3
Gain
Setting
G1
G2
G3
LnaGain
„001‟
„010‟
„011‟
Relative LNA
Gain [dB]
0 dB
-6 dB
-12 dB
NF
[dB]
7
11
16
IIP3
[dBm]
-12
-8
-5
Page 27
Tel: [phone] Fax: [phone] E-mail: [e-mail] http://www.hoperf.com