Gaussian Monocycle Pulse Research Articles

Switchable UWB pulse generation using a phase modulator and a reconfigurable asymmetric Mach-Zehnder interferometer

We propose a new scheme to generate polarity-switchable ultrawideband (UWB) Gaussian pulses in the optical domain by use of a phase modulator and a reconfigurable asymmetric Mach-Zehnder interferometer (AMZI). In the proposed system, an optical carrier is phase modulated by a Gaussian pulse train and then sent to a first-or second-order AMZI. The system is equivalent to a first- or second-order differentiator for the production of Gaussian UWB monocycle or doublet pulses. The polarity of the generated UWB pulses can be switched by adjusting the phase difference between the two interference components in the AMZI. An experiment is performed. Gaussian monocycle and doublet pulses with fractional bandwidths of about 177% and 140% are generated. The polarity switchability of generated UWB pulses is also experimentally confirmed.

All-Optical 500-Mb/s UWB Transceiver:An Experimental Demonstration

We propose and demonstrate experimentally, for the first time, a prototype for all-optical ultra-wideband (UWB) transceiver at 500 Mb/s. We report 1) UWB pulse optimization that takes into account the transmitter RF front end and the U.S. federal communications commission (FCC) spectral mask, 2) a new approximate match filter receiver using optical signal processing, and 3) modulation at 500 Mb/s. Our previous optimization of UWB pulse shapes was based only on the FCC spectral mask, without taking into account the frequency response of the RF components (amplifier and antenna) in the UWB transmitter. Here, we modify our pulse optimization technique to ensure that the equivalent isotropic radiated power (EIRP) from the transmitter meets FCC specifications. For the RF hardware used, we achieve 63.6% efficiency over the FCC mask, which yields an 11.6- and a 5.9-dB improvement over Gaussian monocycle and doublet pulses, respectively. We also introduce simple optical signal processing at the receiver that allows the incoming RF signal to be matched against a square pulse whose duration is adapted to the channel. The exact matched filter would require a new optimized pulse that would include not only hardware frequency response but channel effects that vary with antenna placement as well. The proposed approximation allows a simple variation of the pulse duration: an increase to account for pulse expansion in the channel but an upper limit to combat multipath effects. Finally, we demonstrate the optimized pulse and approximate match filter receiver at 500 M/s. We attain a 10-6bit error rate at a 65-cm separation line of sight (LOS) link with simple on-off keying and no forward error correction.

UWB Pulse Generation and Distribution Using a NOLM Based Optical Switch

An approach is proposed in this paper to generate ultra-wideband (UWB) pulses based on cross-phase modulation (XPM) effects in nonlinear optical loop mirror (NOLM). The NOLM can be considered as an optical switch which is controlled by pump to generate positive and negative Gaussian pulses, which are then delayed by SMF and combined to generate both Gaussian monocycle and doublet pulses. These two pulse shapes can be switched at a high speed by controlling the on-off of one of the probe. In addition, the SMF acting as a chromatic dispersion media in generating the UWB pulses can also be used to distribute the UWB signals from the central station (CS) to remote access points (AP). Different distance between CS and remote APs has no effects on the generated UWB pulses by adopting a wavelength tunable laser as probe.

Gaussian Monocycle Pulse Transmitter Using 0.18 $\mu{\hbox {m}}$ CMOS Technology With On-Chip Integrated Antennas for Inter-Chip UWB Communication

A single-chip Gaussian monocycle pulse (GMP) transmitter using 0.18 mum CMOS technology with an on-chip integrated antenna was developed for inter-chip ultra-wideband (UWB) communication. Ultra-short GMP signals of 280 ps duration, -20.2 dB ringing level and 3.6 GHz center frequency were generated with the power consumption of 12.6 mW at 1.8 V. Intra- and inter-chip transmissions and receptions of the generated GMP were successfully demonstrated at a pulse repetition rate of 1.16 Gb/s by use of on-ship integrated dipole antennas.

Ultra-Wideband Waveform Generator Based on Optical Pulse-Shaping and FBG Tuning

We propose and demonstrate experimentally a prototype for ultra-wideband (UWB) waveform generator based on optical pulse shaping. The time-domain pulse shape is written in the frequency domain, and a single-mode fiber performs frequency-to-time conversion. A U.S. Federal Communications Commission (FCC)-compliant power efficient pulse shape is inscribed in the frequency domain by a fiber Bragg grating (FBG) with an excellent match between optimized and measured pulses. Two other popular UWB pulse shapes (Gaussian monocycle and doublet pulses) are achieved by proper tuning of two FBG-based variable optical filters. A balanced photodetector removes an unwanted rectangular pulse superimposed on the desired waveform, assuring compliance at low frequency.

An Electrically Switchable Optical Ultrawideband Pulse Generator

A novel electrically switchable optical ultrawideband (UWB) pulse generator that is capable of generating both Gaussian monocycle and Gaussian doublet pulses by using a polarization modulator (PolM) and a fiber Bragg grating is proposed and experimentally demonstrated. The polarity and the shape of the generated UWB pulses can be electrically switched by adjusting the voltages applied to two arbitrary wave plates (AWPs), which are incorporated at the input and the output of the PolM to adjust the polarization state of the lightwaves. The key component in the UWB pulse generator is the PolM, which is a special phase modulator that can support both transverse electric and transverse magnetic modes but with opposite phase modulation indexes. Depending on the polarization state of the incident lightwave to the PolM that is linearly polarized and aligned to one principle axis of the PolM or circularly polarized, UWB monocycle or doublet pulses are generated. The polarity of the UWB pulses can be electrically switched by adjusting the voltages applied to the AWPs. The proposed system is implemented, and the generation of UWB monocycle and doublet pulses is experimentally demonstrated. Gaussian monocycle and doublet pulses with a fractional bandwidth of about 150% and 160% are experimentally generated. The proposed electrically switchable optical UWB pulse generator has the potential for applications in UWB communications and radar systems that employ pulse polarity modulation and pulse shape modulation schemes.

Spectrum Shaping and NBI Suppression in UWB Communications

This paper investigates spectrum shaping in ultra-wideband (UWB) communications in order to introduce spectral nulls to limit interference with narrowband signals. Each transmitted symbol is represented by a "coded Gaussian monocycle pulse" in which Gaussian monocycles are weighted, delayed and summed in accordance with a designed codeword. The use of the Gaussian monocycle ensures that the UWB spectrum mask established by the Federal Communications Commission (FCC) is met, and the codeword is designed to generate a spectral null at the frequency or frequencies being used by existing narrowband devices. Signals obtained with different spectrum shapings (e.g., Butterworth, Chebyshev, elliptical) and by introducing nulls at multiple interference frequency bands are discussed. This approach can be used in various systems; as one application, we simulate the performance of a coded monocycle UWB system with a spectral null in the presence of narrowband interference (NBI) using single carrier block transmission with frequency domain equalization (SC-FDE), and compare its performance with that of an uncoded SC-FDE UWB system using a single Gaussian monocycle. Our results show that NBI can be effectively suppressed by transmitting and matched filtering the pulse with a spectral null at the interference frequency, therefore improving the robustness of UWB systems to NBI

Switchable optical UWB monocycle and doublet generation using a reconfigurable photonic microwave delay-line filter

Optically switchable Ultra-Wideband (UWB) monocycle and doublet pulse generation using an optically reconfigurable photonic microwave delay-line filter is proposed and demonstrated. The microwave filter can be reconfigured as a two- or three-tap microwave filter with coefficients of (1, -1) or (1, -2, 1). The function of the two- or three-tap microwave filter is equivalent to an operation of a first- or second-order difference, which can be approximated as a first- or second-order derivative. When a Gaussian pulse is inputted to the two- or three-tap microwave delay-line filter, a Gaussian monocycle or doublet pulse is generated. The proposed photonic microwave delay-line filter is implemented using a polarization modulator (PolM), a length of polarization maintaining fiber (PMF), and a balanced photo-detector (BPD). In the experiment, Gaussian monocycle and doublet pulses with a fractional bandwidth of about 170% and 130% are generated. The switchability of the proposed UWB pulse generator in pulse shape and polarity is also experimentally demonstrated.

Design of a new optical impulse radio system for ultra-wideband wireless communications

This study presents a novel optical impulse radio (IR) system for generating Gaussian monocycle pulses for ultrawideband (UWB) radio-over-fiber communications. The proposed system consists of a gain-switched Fabry-Perot laser diode, tunable filter, Er/sup 3+/-doped fiber amplifier and a microwave differentiator. This new optical technique can tolerate pulse dispersion and avoid the generation of intersymbol interference (ISI) due to its easily adjustable optical pulse width, and can perform better radio communication in terms of generating the UWB signal. Simulated results indicate that the generated Gaussian pulse signal can provide a bandwidth of several gigahertz for the high-bit-rate transmissions. Moreover, experimental and analytical results demonstrate that the proposed system can generate high-quality Gaussian pulse trains for applying future high-bit-rate UWB wireless communications.

Signal Transmission Characteristics between Si Chips with Air Gap using Si Integrated Dipole Antennas

Transmission characteristics of integrated linear dipole antennas fabricated on Si substrates were investigated for inter-chip signal transmission of wireless interconnections of Si ultra-large scale integrated circuits. Linear dipole antennas 1–6 mm long were fabricated on oxidized P-type Si substrates with resistivities of 10, 79.6, and 2290 Ω·cm. The transmission characteristics were investigated in the frequency and time domains. The transmission gain of a 4-mm-long dipole antenna fabricated on a 2.29 kΩ·cm resistivity Si substrate was -10 dB for a distance of 3 mm. A Gaussian monocycle pulse with a pulse width of 70 ps and a bandwidth of 20 GHz was transmitted and received successfully between Si chips with an air gap.

A 2.4 GHz Differential Wavelet Generator in 0.18 µm Complementary Metal–Oxide–Semiconductor for 1.4 Gbps Ultra-Wideband Impulse Radio in Wireless Inter/Intra-Chip Data Communication

Ultra-wideband impulse based radio systems use Gaussian monocycle pulses as transmitted signals at the transmitting end and as template signals at the receiving end. In this paper we present a new fully integrated differential Gaussian monocycle pulse generator in 0.18 µm complementary metal–oxide–semiconductor (CMOS) technology. Here the Gaussian monocycle pulse is generated from triangular shaped pulse by a single differentiator circuit and it is then converted into differential form by using a single input to dual output amplifier. The developed circuit occupies a small area of 0.06 mm2 and consumes a total power of 44 mW at 1.8 V. The transmission of the generated differential Gaussian monocycle pulse at a rate of 1.4 Gbps through integrated dipole antenna in the same Si-substrate for intrachip communication in future ultralarge scale integrated circuit (ULSI) is verified by simulation and results are presented here.

Analysis of Transmission Characteristics of Gaussian Monocycle Pulses for Silicon Integrated Antennas

Ultra wideband (UWB) signal transmission characteristics of Si integrated antennas were investigated and analyzed by measurement and high accuracy simulation program with integrated circuit emphasis (HSPICE). The transfer functions were derived from a three-dimensional (3D) electromagnetic field simulator. HSPICE simulation was performed using the derived transfer functions. The measured results were compared with HSPICE results in terms of the scattering parameter and the received signal. Moreover, the effect of load impedance on the receiving antenna was investigated, and the peak-to-peak voltage of the received signal was improved by increasing the load impedance.

Optically Based Direct Sequence Binary Phase Shift Keying Modulation Scheme for Indoor Ultrawide-Band Wireless Systems

In this study, we focus on the design of an optical-based ultrawide-band (UWB) transmission system with a direct sequence-binary phase shift keying (DS-BPSK) modulation scheme for indoor wireless communication environments. The distinct pseudorandom noise (PN) code sequences are assigned to users that share a channel in the UWB multiple-access system. Filtered second-order Gaussian monocycle pulses can provide large bandwidths for very high-speed communications. Moreover, fiber dispersion and intersymbol interference (ISI) problems can be avoided by properly adjusting pulse width. The simulation and analytical results demonstrate that the presented scheme indeed provides several GHz bandwidths for future indoor UWB wireless applications.

Modified pulse shaper design with picosecond duration and wideband response for UWB applications

AbstractA simple, compact pulse shaper of inverse Gaussian monocycle with picosecond duration and wideband response is proposed in this paper. By modifying the conventional pulse shaping circuit, the pulse shaper utilizes the RC differentiator and Schottky diode to construct the clamping circuit, and form an inverse Gaussian monocycle pulse. In addition, the short‐stub is used for constructing the resistive matching network as well as adjusting the shape of inverse Gaussian monocycle pulse. In applications, an ultra‐short inverse Gaussian monocycle pulse with duration of 600 ps, symmetry of 100%, and ring level of 5.8% has been obtained. Meanwhile, the frequency response presents the characteristic of wideband spectrum with a −3‐dB BW of 141.7%. Both the measured and simulated results are in good agreement with the time and frequency responses. © 2006 Wiley Periodicals, Inc. Microwave Opt Technol Lett 48: 744–749, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.21462

Implementation of a new ultrawide-band impulse system

In this letter, we propose a new optically based system to generate ultrawide-band (UWB) impulse signals. The system includes a Fabry-Pe/spl acute/rot laser diode under gain-switched operation and an erbium-doped fiber amplifier used as an external-injection light source to generate optical pulses on the transmitter end, together with a PIN photodiode and a first-order microwave differentiator to convert optical pulses into electrical Gaussian monocycle pulses on the receiver front-end. The experimental and fast Fourier transform analytical results demonstrate that the proposed system can generate UWB impulse signals and provide several gigahertz bandwidths for future applications of high-bit-rate UWB wireless systems.

Ultrawideband characteristics of fractal dipole antennas integrated on Si for ULSI wireless interconnects

Ultrawideband characteristics of Sierpinski carpet fractal antennas fabricated on silicon substrates with the resistivities of 2290, 79.6, and 10 /spl Omega//spl middot/cm were investigated. The return losses lower than -10 dB and high transmission gains of approximately -14 dB were obtained for the antennas with 10-mm distance on the Si substrate with the resistivity of 2290 /spl Omega//spl middot/cm in the frequency range from 18 to 26.5 GHz. Gaussian monocycle pulses with 70 ps pulsewidth were transmitted in the Si substrates successfully and the corresponding voltage gains were -23, -26, and -39 dB for the Si resistivities of 2290, 79.6, and 10 /spl Omega//spl middot/cm, respectively.

Transmission Characteristics of Gaussian Monocycle Pulses for Inter-Chip Wireless Interconnections Using Integrated Antennas

Performance of integrated dipole antennas on Si substrates was investigated for inter-chip signal transmission in wireless interconnections for Si ultra-large scale integrated circuits (ULSI). Linear dipole antennas 4 mm long were fabricated on P-type Si substrates with a resistivity of 10 Ω·cm in an inter-chip stacked structure. Inter-chip antenna transmission gains were measured for the dipole antennas at a vertical distance of 2.86 mm and a horizontal distance of 3 mm when Si substrates with a resistivity of 2.29 kΩ·cm were inserted. A transmission gain of -30 dB and no dependence on vertical distance were observed. Gaussian monocycle pulses with a pulse width of 70 psec could be transmitted successfully in the inter-chip stacked structure. Antenna transmission gain and peak-to-peak voltage between Si chips were improved using a high resistivity Si substrate.

A novel ultra-wideband pulse design algorithm

We present a new algorithm to numerically generate pulses that not only have a short time duration for multiple access, but also meet the power spectral constraint of Federal Communications Commission (FCC) ultra-wideband (UWB) mask. In fact, applying our algorithm to the FCC spectral mask for UWB systems can lead to the design of multiple orthogonal pulses that are compliant. Our algorithm presents a flexible and systematic method for generating UWB pulses that have many advantages over the Gaussian monocycle pulse.