The RFID interrogator further comprises a microcontroller module adapted to
provide high level commands to the interrogator, a DSP module for
processing received/transmitted data and controlling radio operations, and
a radio module for transmitting and receiving RF signals to/from an RFID
transponder. A first embodiment of the RFID interrogator comprises an RF
carrier source providing a carrier signal, a processor providing an
information signal, and plural modulation stages coupled to the RF carrier
source for modulating the information signal onto the carrier signal using
on/off keying modulation. The plural modulation stages are controlled in
unison by control signals the said processor. The plural modulation stages
provide dynamic range of greater than 25 dB between respective on and off
states of the modulated signal. A second embodiment of the RFID
interrogator comprises an RF carrier source providing a carrier signal, a
modulator receiving the carrier source and modulating an information
signal thereon to provide a modulated RF signal, and an amplification
stage coupled to the modulator. The amplification stage splits the
modulated RF signal into first and second components, and amplifies the
first and second components separately. The first and second components
are thereafter recombined. The split operation of the amplification stage
provides a better match with the downstream transmission path than an
individual amplifier. A third embodiment of the RFID interrogator
comprises an RF carrier source providing a carrier signal, a demodulator
combining a received signal with the RF carrier to provide a baseband
signal, and an attenuator coupled to the demodulator for absorbing high
frequency components of the baseband signal. The baseband signal further
comprises in phase (I) and quadrature phase (Q) components. The high
frequency components of the baseband signal pass through the high-pass
filter to the resistor termination, where they are absorbed.