rfw102 ETC-unknow, rfw102 Datasheet - Page 12

• Manufacturer Part Number: rfw102
• Description: Rfw102 Transceiver Chipset Shortrang
• Manufacturer: ETC-unknow

Datasheet
October 2002
Rev. 1.03
Receiving Link
The receiving link is a one stage down converting link, followed by a de-spreading function (implemented by
the SAW correlator) and an ASK receiver. All the signal processing is done in the IF, or in the base-band.
Basically, it consists of 4 elements:
•
•
•
•
Low Noise Block
The Low Noise Block is the input from the antenna on one side, and the output is attached to the SAW
correlator on the other side. Since there is no RF filter between the antenna and LNA1, other than a simple
printed filter, a wide dynamic range of transmitting/receiving is required, therefore, a very high dynamic
range is featured in this front – end block. After this block comes the SAW correlator, which functions also as
a filter that rejects out of band signals, and suppress in-band interference.
Low Noise Block (LNB) features:
•
•
•
•
•
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Peak Detector
The peak detector is the next stage after the SAW correlator. It functions as an envelope signal detector,
moving from IF directly to Base Band. It is the 1
high range of input signals, a high dynamic range is its main feature.
Two peak detectors are applied in parallel a ‘fast’ peak detector, and a ‘slow’ one. The difference between
the two is their output bandwidth. The ‘fast’ peak detector has a bandwidth of 10MHz. The ‘slow’ peak
detector has a bandwidth that will be determined by an external capacitor, connected between pin 17 and
system GND.
In order to maintain the high dynamic range that is required, a logarithmic peak detector is applied. It can be
modeled as V
© 2002, RFWaves LTD.
Antenna interface
A low noise block – this element is a low noise-amplifier and a down conversion unit
The SAW correlator – to be used as a de-spread function
A logarithmic peak detector
A decision stage
Gain: 38dB
Source = input impedance: Antenna 200Ω (differential)
Load (SAW Correlator): 200Ω, none differential
Compression points:
Noise figure: NF < 16dB
Image rejection > 30dB
o
o
Input IP1 > -35dBm
out
=α*P
in,
LNA1
where P
in
Figure 11: Receiving Link Block Diagram
is in dBm (logarithmic), and V
1952MHz
Low Noise Block
LNA2
st
stage of the ASK receiver. Since its input may have a very
SAW
out
is in volts (linear).
Detector
Peak
RFW102 ISM Transceiver Chipset
{optional AGC}
{optional AGC}
Decision
DATA out
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