phase modulator definition of phase modulator in the Free Online Encyclopedia.

phase modulator [′fāz ‚mäj·ə‚lād·ər]

(electronics)

An electronic circuit that causes the phase angle of a modulated wave to vary (with respect to an unmodulated carrier) in accordance with a modulating signal.

Phase modulator

An electronic circuit that causes the phase angle of the modulated wave to vary (with respect to the unmodulated carrier) in accordance with the modulating signal. Since frequency is the rate of change of phase, a phase modulator will produce the characteristics of frequency modulation (FM) if the frequency characteristics of the modulating signal are so altered that the modulating voltage is inversely proportional to frequency. Commercial FM transmitters normally employ a phase modulator because a crystal-controlled oscillator can then be used to meet the strict carrier-frequency control requirements of the Federal Communications Commission. The chief disadvantage of phase modulators is that they generally produce insufficient frequency-deviation ratios, or modulation index, for satisfactory noise suppression. Frequency multiplication can be used, however, to increase the modulation index to the desired value, since the frequency deviation is multiplied along with the carrier frequency. See Phase-modulation detector

Many types of phase modulators have been devised. A simple modulator is shown in the illustration. In this circuit the modulating voltage changes the capacitance of the varactor diode. The phase shift depends upon the relative magnitudes of the capacitive reactance of the varactor diode and the load resistance R. Therefore the phase shift varies with the modulating voltage and phase modulation (PM) is accomplished. However, the phase shift is not linearly related to the modulating voltage if the PM exceeds a few degrees, because the phase shift is not linearly related to the capacitance and the capacitance of the varactor diode is not linearly related to the modulating voltage. See Varactor

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No references found	There are intensity modulators for converting input electrical signals to optical intensity signals and phase modulators for converting them to optical phase signals. Fujitsu To Release the World's Lowest Drive Voltage (4.0v) DQPSK LN ... by JCN Newswires Yi-Hsin Lin, University of Central Florida Polarization-independent liquid crystal phase modulator with a large phase shift and low operating voltage Summary: A polarization-independent liquid crystal phase modulator with a large phase shift and low operating voltage is demonstrated for the first time. The Optical Society of America and Bookham New Focus Announce ... by Business Wire The Mach-Zehnder interference type, lithium niobate (LN) modulator has been used as a binary intensity or phase modulator in high-speed transmitters, but there is a trade-off between driving voltage and bandwidth and it was considered to be virtually impossible to raise the operation speed to at least 100 Gbps. NTT Announces Successful Demonstration of World's Largest Capabcity ... by JCN Newswires	phase equalizer phase equilibria Phase Equilibrium phase excursion phase factor Phase Fixation phase front phase function phase generator phase inequality phase integral phase integral method phase inversion Phase Inverter phase jitter phase lag phase lead phase localizer phase lock phase magnet phase margin phase matching phase meter phase modifier Phase Modulation phase modulator Phase of the Moon Phase Plane Analysis phase plate phase portrait phase problem phase quadrature phase ratio phase resonance phase response phase reversal phase reversal modulation Phase Rule phase shift Phase Shifter Phase Shifter, Microwave phase solubility Phase Space phase speed Phase Splitter phase stability Phase Stability in Particle Accelerators phase titration phase transfer catalysis phase transformation phase transformer	Phase Linear Interferometer Experiment phase localizer Phase lock Phase Lock Demodulator Phase lock loop phase locked Phase locked loop Phase Locked Loop Control phase magnet Phase margin phase matching Phase Measurement System Phase meter Phase meter phase microscope phase microscope phase microscope phase microscope, phase-contrast microscope phase microscope, phase-contrast microscope phase microscope, phase-contrast microscope phase modifier Phase modulated Phase modulated phase modulation phase modulation phase modulation phase modulation Phase Modulation On Pulse Phase Modulation-Demodulation Phase Modulation/Frequency Modulation phase modulator Phase noise Phase Noise Analysis Phase Noise Analysis Tool Phase Noise Correction Phase Noise Measurement Module Phase Noise Suppression Phase of Arrival phase of cell division Phase of Education phase of maximum slope phase of the moon phase of the moon phase of the moon Phase of vibration Phase Offset Estimation Error Variance Phase One Phase One Consulting Group Phase One Digital Artist Series Phase One Engineering Team Phase One Engineering Technology Phase One Enviornmental Site Assessment Phase One Environmental Site Assessment phase one study Phase Only Filter Phase Opposition Disposition phase out phase out phase out phase out phase out

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There are intensity modulators for converting input electrical signals to optical intensity signals and phase modulators for converting them to optical phase signals.

Fujitsu To Release the World's Lowest Drive Voltage (4.0v) DQPSK LN ... by JCN Newswires

Yi-Hsin Lin, University of Central Florida Polarization-independent liquid crystal phase modulator with a large phase shift and low operating voltage Summary: A polarization-independent liquid crystal phase modulator with a large phase shift and low operating voltage is demonstrated for the first time.

The Optical Society of America and Bookham New Focus Announce ... by Business Wire

The Mach-Zehnder interference type, lithium niobate (LN) modulator has been used as a binary intensity or phase modulator in high-speed transmitters, but there is a trade-off between driving voltage and bandwidth and it was considered to be virtually impossible to raise the operation speed to at least 100 Gbps.

NTT Announces Successful Demonstration of World's Largest Capabcity ... by JCN Newswires

Phase Linear Interferometer Experiment
phase localizer
Phase lock
Phase Lock Demodulator
Phase lock loop
phase locked
Phase locked loop
Phase Locked Loop Control
phase magnet
Phase margin
phase matching
Phase Measurement System
Phase meter
Phase meter
phase microscope
phase microscope
phase microscope
phase microscope, phase-contrast microscope
phase microscope, phase-contrast microscope
phase microscope, phase-contrast microscope
phase modifier
Phase modulated
Phase modulated
phase modulation
phase modulation
phase modulation
phase modulation
Phase Modulation On Pulse
Phase Modulation-Demodulation
Phase Modulation/Frequency Modulation

phase modulator

Phase noise
Phase Noise Analysis
Phase Noise Analysis Tool
Phase Noise Correction
Phase Noise Measurement Module
Phase Noise Suppression
Phase of Arrival
phase of cell division
Phase of Education
phase of maximum slope
phase of the moon
phase of the moon
phase of the moon
Phase of vibration
Phase Offset Estimation Error Variance
Phase One
Phase One Consulting Group
Phase One Digital Artist Series
Phase One Engineering Team
Phase One Engineering Technology
Phase One Enviornmental Site Assessment
Phase One Environmental Site Assessment
phase one study
Phase Only Filter
Phase Opposition Disposition
phase out
phase out
phase out
phase out
phase out