III.
Receiver Characteristics
Acceptable Input Voltage Range
Testing of the RadioProcessor with C680 removed showed that the receiver is linear
within the tested range of 0.5V to 2.0V.
The input voltage to the RadioProcessor must be positive. To measure a range of
voltages from negative to positive, introducing a DC offset that will shift the required voltage
range into the linear operating region of the RadioProcessor is acceptable.
Frequency Characteristics
Illustration 2 below demonstrates the characteristics of the RadioProcessor at low
frequencies. The green line represents the characteristics with capacitor C680 and the CIC
filter enabled. The capacitor leads to a large attenuation at low frequencies, while the CIC
filter attenuates higher frequencies.
The red line represents the characteristics of the receiver once the capacitor C680 has
been removed from the receiver circuit. Once the capacitor has been removed, low
frequencies down to DC can be acquired by the RadioProcessor. The CIC filter was enabled
for this test, leading to attenuation at higher frequencies.
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2010-01-29
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Illustration 2:
Low frequency characteristics of the RadioProcessor receiver.
Capacitor Removed
With Capacitor
