EC5701 – MILLIMETER AND OPTICAL
WAVE COMMUNICATION
SEMINAR
TRANSCEIVER WITHOUT MIXER
DONE BY:
KARTHICK K - 2021504013
TRANSCEIVER WITHOUT MIXER
• It refers to a six port radio that uses no mixers in transceivers.
• Six port technology is a passive linear device with two input ports
and three outputs.
• A phase shifter is used to adjust the phase between RF and LO
• Diode detectors are used on the output ports as the frequency
converters, instead of a mixers.
• Five port technology has been extended to be a direct digital
transmitter and can be used for SDRs (Software defined Radio)
since it can accommodate different wireless modulation standards
without requiring hardware modification.
PIONEERING SIX-PORT INTERFEROMETER
(SPI) RADIO RECEIVER
• First use of six-port radio in SPI receiver at millimetre-wave
frequencies.
• Required new design approaches for radio functionality.
• Initial modifications enabled narrow-band, single-carrier digital
demodulation.
• Led to advancements in phase spectrum modulation/demodulation
(PSMS/PSDS) using SPI modulators and demodulators.
ANALOG SIGNAL PROCESSING IN SIX-PORT
RADIO MODULATOR AND DEMODULATOR
Modulator: Performs vector-based analog signal processing on phase-
modulated pulse waves using the phase spectrum of reference pulses.
Demodulator: Reverses signal processing to retrieve original data
directly from interferometer outputs, using an analog or digital decoder.
CHANGES MADE IN SIX PORT RADIO
• The six-port interferometer radio receives the reference and
modulated (or unknown) signals at different input ports,
accommodating both single and multiple carrier signals.
• A new Phase Spectrum Modulation Scheme (PSMS) is
introduced, enabling phase modulation of digital data across
the entire phase spectrum of a monocycle pulse, on either a
single frequency carrier or multiple carriers—making the six-
port radio adaptable for communication applications.
SIX PORT RADIO WITH FOUR
INTERFEROMETER OUTPUT POWER
FIVE PORT RADIO
KEY FEATURES OF SIX-PORT RADIO FOR
QPSK/BPSK TESTING
• New modulator circuit developed for PSMS.
• Simple, fast decoder (analog/digital) retrieves signals from digital data
demodulation.
• DSP algorithms designed for PSMS modulation and PSDS demodulation.
• Demonstrated digital data transmission (wired & wireless) in lab with
phase-linear antennas.
• Unique six-port radio hardware and software for broadband
communication.
SIX PORT DATE RATA AND LIMITATIONS
• The test data rate can be limited by rectangular pulse generator
• The digital or analog decoders in demodulator , speed of switch
matrix in modulator and speed of DSP in radio platform are the
ultimate data rate limiting factors for digital transmission in ideal
propagation .
• Speed can be increased by upgrading the present technology with
meta materials , fast acting switch matrices , rapid signal processing
algorithms and coding.
• Six port radios can work with QPSK/BPSK. More research is going on
for QAM/MPSK.
SIX-PORT RADIO RESEARCH AND
MODULATION TECHNIQUES
• Research conducted with QPSK/BPSK data; ongoing development for
QAM/MPSK.
• Primarily uses PSMS modulation to directly modulate/demodulate
digital data.
• Unlike traditional radios, no need for nonlinear mixing
(heterodyne/superheterodyne).
• Six-port radios with PSMS/PSDS enable digital data transmission over
wireless channels.
• Linear phase Tx/Rx antennas and six-port platform sufficient for radio
testing
PLATFORM COMPONENTS AND CAPABALITIES
• The platform includes two six-port interferometers (for
modulation and demodulation), a four-channel DSP, four
SPDT switches, two Rx/Tx antennas, and components such as
wideband, short, and open circuit terminations.
• It provides cognitive radio hardware and software at a low
cost, supporting both wideband and narrow-band performance
with integrated chips for QPSK/BPSK, and the potential to
extend to QAM/MPSK and other digital formats.
DEMODULATOR
• The demodulator is housed in a black box with two inputs: a
reference signal and a modulated or unknown signal.
• It performs linear analog vector addition and division on the input
signals (CW or pulsed) within a wide operating bandwidth defined by
pulse shape and component limitations.
• The results are routed to four output ports, with one port potentially
having zero amplitude and the remaining three having nonzero
amplitudes, useful for QPSK/BPSK demodulation.
QPSK/BPSK MODULATION DETECTION USING DSP
OR ANALOG COMPARATOR
• A 90° phase shift in the input signal results in one output port
having zero amplitude, and the remaining ports having
nonzero amplitudes.
• Feeding the four output signals to a DSP or four-channel
analog amplitude comparator enables rapid detection of
QPSK/BPSK modulation states.
• Simple DSP algorithms or analog comparators can quickly
identify the modulation state of the data.
DETECTION AND MODULATION STATE
DETERMINATION IN SIX-PORT RADIO
• The amplitudes of the four RF output signals from the demodulation
interferometer can be detected using Schottky diodes or high-speed
amplitude sensors.
• These outputs allow for rapid determination of the modulation state
for QPSK/BPSK data.
• With DSP circuitry and appropriate algorithms, QAM/MPSK
modulation states can be determined using four nonzero output power
levels.
SPI CIRCUIT ARCHITECTURES AND INTEGRATION
• Planar SPI circuits integrated with planar antennas enable low-cost,
mass fabrication of miniature radio chips.
• Interferometer circuits consist of passive linear components like
power dividers, hybrid couplers, and transmission lines.
• Example: A six-port circuit with four Rat-Race couplers and 50Ω
microstrip transmission lines offers low loss, good phase and
amplitude balance, and high output isolation.
SUBSTRATE AND WAVEGUIDE
TECHNOLOGIES IN SIX-PORT RADIO
• For millimeter-wave applications, rectangular waveguides, substrate
integrated waveguides (SIWs), or dielectric waveguides can be used.
• Optical integrated waveguides are applicable for submillimeter-wave
and optical frequencies.
• Six-port receivers allow arbitrary frequency selection, though
nonlinearity in diode detectors may cause distortion, which can be
mitigated using nonlinearity compensation methods.
DEMODULATORS
SIMULATION OF S PARAMETERS PHASE
MODULATOR DESIGN AND REFLECTION
COEFFICIENTS FOR QPSK/BPSK AND QAM/MPSK
• The modulator for BPSK/QPSK modulation includes switches and
output terminations (shorts or open circuits).
• Switch activation is controlled by DSP output signals.
• For BPSK/QPSK, terminal shorts provide reflection coefficients (-1),
and open circuits provide reflection coefficients (+1).
• For QAM/MPSK, passive circuit reflection coefficients must be less
than unity, with C having an angle between 0° and 360°.
• High data rates can be achieved with quality switches and fast
terminations for QPSK/BPSK
CONTD.
PERFORMANCE COMPARISON AND SIX-
PORT RECEIVER ADVANTAGES
• Simulated output signal constellations for QPSK at different SNRs (30
dB and 10 dB) are shown.
• A comparison between the six-port receiver and homodyne receiver
at 60 GHz shows the six-port receiver has superior bit error rate (BER)
performance.
• The six-port architecture is less sensitive to LO power variations and
phase errors compared to the homodyne receiver.
• The six-port receiver requires significantly less LO power for a similar
bandwidth, making it ideal for compact, high-performance, low-cost
wireless millimeter-wave communication devices.
CONTD.
THANK YOU
