A CMOS Ultra Low-Power and Highly Efficient UWB-IR Transmitter for WPAN Applications

This brief presents an on–off $LC$ oscillator-based ultrawideband impulse radio (UWB-IR) transmitter for long-range application. A thorough theoretical analysis of the pulse generation is provided. Implemented in a 0.18-$muhbox{m}$ CMOS, the transmitter works in the UWB lower band of 3–5 GHz and consumes an ultralow average power of 236 $muhbox{W}$ at 1.8-V power supply. UWB pulses with a bandwidth of 2 GHz and 10-dB sidelobe suppression are generated. The transmitter can deliver a large differential output swing of 4.9 V under 100-$Omega$ load with the highest power efficiency of 25.4% to date. It is targeted for wireless sensor network (WSNs) and wireless personal area network (WPAN) applications.      

System and Circuit Design for an MB-OFDM UWB Frequency Synthesizer

This paper presents a complete top–down design and experimental results for a fast-hopping 11-band 3–10-GHz frequency synthesizer. The system requirements for a synthesizer in an ultrawideband (UWB) radio are discussed. The synthesizer specifications for 480-Mb/s- and 1-Gb/s-data-rate multiband orthogonal-frequency-division-multiplexing UWB radios using quadrature phase shift keying and 16-quadrature amplitude modulation, respectively, are provided. The circuit-level implementation of this microwave system is described in detail including layout considerations. Fabricated in a 0.25- $mu{hbox{m}}$ SiGe BiCMOS process and integrated in a receiver, the synthesizer was characterized in a quad-flat-no-leads package while being mounted on an FR-4 substrate. Measurement results and a model–hardware correlation analysis are presented.      

A Single-PLL UWB Frequency Synthesizer Using Multiphase Coupled Ring Oscillator and Current-Reused Multiplier

A single phase-locked loop (PLL) frequency synthesizer for a Mode-1 multiband orthogonal frequency-division multiplexing (MB-OFDM) ultrawideband (UWB) system is realized in 0.13-$mu hbox{m}$ CMOS. A current-reused multiply-by-1.5 circuit and a multiphase coupled ring oscillator are adopted to reduce the power consumption. For a 4.488-GHz signal, the measured image sideband is $-$40 dBc. The measured switching time from 3.342 to 4.488 GHz is 1.5 ns. The area is $0.85 times 0.9 hbox{mm}^{2}$ and the power is 31.2 mW for a 1.2-V supply voltage.      

A CMOS UWB Pulse Generator for 6–10 GHz Applications

A CMOS ultra wideband (UWB) pulse generator with low energy dissipation and high peak amplitude is presented for 6–10 GHz applications. The pulse generator complies with the FCC spectral mask for indoor UWB systems. It consists of a glitch generator, a pulsed oscillator, and a pulse shaping filter. The pulsed oscillator is switched on by the glitch signal only for a short duration, so as to make a UWB pulse. For sub-nanosecond pulse generation, a pulsed oscillator with fast transient response is proposed. A pulse shaping filter makes the oscillator output fall into the FCC spectral mask. The pulse generator is fabricated using a 0.18 $mu$ m CMOS process. The core chip has a size of 0.11 mm $^{2}$. It shows pulse duration of about 500 ps with ${-}10$ dB bandwidth of 4.5 GHz from 5.9 to 10.4 GHz. The energy consumption is 27.6 pJ per pulse with a peak-to-peak amplitude of 673 mV on a 50 $Omega$ output load. The generated pulses are very coherent with 1.8 ps RMS jitter.      

Phase-Only Matched Filtering of Ultrawideband Arbitrary Microwave Waveforms via Optical Pulse Shaping

We demonstrate compression of ultrawideband (UWB) microwave arbitrary waveforms via phase-only matched filtering implemented in a programmable hyperfine resolution optical pulse shaper. We synthesize spread-time UWB electrical waveforms and utilize programmable microwave photonic phase filters to impose the opposite of a waveform's spectral phase on its spectrum. This enables us to compress an UWB microwave waveform to its corresponding bandwidth-limited pulse duration via phase filtering. As an example, we present compression of a linear frequency-modulated electrical waveform with ${>}15$ GHz frequency content with almost 200% fractional bandwidth with ${sim}733$ ps temporal window to a 40-ps duration pulse with more than 14-dB gain in peak power. Our technique is programmable and we believe it is applicable to a wide range of arbitrary spectral phase modulated UWB radio frequency (RF) waveforms.      

基于注入锁定法布里-珀罗型激光二极管的超宽带信号产生技术

提出了一种基于三波长注入法布里-珀罗型激光二极管(FP-LD)产生超宽带(UWB)信号的方案。在FP-LD不同激射模式中注入一路信号光和两路直流探测光,实现多波长变换并得到两路反码输出和一路正码输出;再通过光纤进行色散走离,使不同波长信号之间产生时延,形成UWB脉冲,最后经过光电转换产生UWB信号。对所提出的UWB信号产生方案的原理进行分析,并对UWB信号的波形以及频谱特性进行了实验研究。在此基础上,进行了1.25Gb/s非归零码(NRZ)信号注入FP-LD产生差分编码UWB信号的实验。实验产生的UWB脉冲信号半峰全宽最小为83.3ps,10dB谱宽约为4.6GHz,其频宽比为107%。     

The design and analysis of a DLL-based frequency synthesizer for UWB application

A delay-locked loop (DLL)-based frequency synthesizer is designed for the ultrawideband (UWB) Mode-1 system. This frequency synthesizer with 528-MHz input reference frequency achieves less than 9.5-ns settling time by utilizing wide loop bandwidth and fast-settling architecture. Additionally, a discrete-time model of the DLL and an analytical model of phase noise of the delay line are proposed in this work. Experimental results show great consistency with predicted settling time and phase noise. The circuit has been fabricated in a 0.18-/spl mu/m CMOS technology and consumes only 54 mW from a 1.8-V supply. It exhibits a sideband magnitude of -35.4 dBc and -120-dBc/Hz phase noise at the frequency offset of 1 MHz.     

A 9-pJ/Pulse 1.42-Vpp OOK CMOS UWB Pulse Generator for the 3.1–10.6-GHz FCC Band

This paper presents the design of a fully integrated ultra-wideband (UWB) pulse generator for the Federal Communications Commission (FCC) 3.1–10.6-GHz band. This generator is reserved for medium rate applications and achieves pulses for an on–off keying (OOK) modulation, pulse position modulation, or pulse interval modulation. This UWB transmitter is based on the impulse response filter method, which uses an edge combiner in order to excite an integrated bandpass filter. The circuit has been integrated in an ST-Microelectronics CMOS 0.13-$mu{hbox{m}}$ technology with 1.2-V supply voltage and the die size is 0.54 ${hbox{mm}}^{2}$. The pulse generator power consumption is 9 pJ per pulse and achieves a peak to peak magnitude of 1.42 V. The pulse is FCC compliant and the generator can be used with a rate up to 38 ${hbox{Mbs}}^{-1}$ with an OOK modulation. Based on the FCC power spectral density limitation, a sizing method is also presented.      

A 16.3 p J/pulse low-complexity and energy-efficient transmitter with adjustable pulse parameters

This paper presents a novel,fully integrated transmitter for 3-5 GHz pulsed UWB.The BPSK modulation transmitter has been implemented in SMIC CMOS 0.13μm technology with a 1.2-V supply voitage and a die size of 0.8×0.95 mm~2.This transmitter is based on the impulse response filter method,which uses a tunable R paralleled with a LC frequency selection network to realize continuously adjustable pulse parameters,including bandwidth,width and amplitude.Due to the extremely low duty of the pulsed UWB,a proposed output buffer is employed to save power consumption significantly.Finally,measurement results show that the transmitter consumes only 16.3 pJ/pulse to achieve a pulse repetition rate of 100 Mb/s.Generated pulses strictly comply with the FCC spectral mask.The continuously variable pulse width is from 900 to 1.5 ns and the amplitude with the minimum 178 mVpp and the maximum 432 mVpp can be achieved.     

Super-Regenerative Architecture for UWB Pulse Detection: From Theory to RF Front-End Design

This paper presents an optimization of the super-regenerative architecture for impulse-based ultrawideband (UWB) technology dedicated to low-data-rate applications. The receiver belongs to the noncoherent category but enables nanosecond resolution for efficient location and tracking applications. Relying on analytical developments, this paper demonstrates how the super-regenerative architecture can suit the UWB context. Such a receiver enables a high RF gain and pulse-matched filter effect with tied power consumption to be achieved, thanks to the suitable control of the inherent unstable behavior. Bit-error-rate simulations based on this architecture are conducted and show a required $Eb/n_{0}$ of 12.5 dB at $10^{-4}$ in the additive white Gaussian noise channel. RF impairment impacts are evaluated and demonstrate good tolerance to the oscillator central frequency accordance and synchronization issue. Specifications of the circuit and controlled signal are drawn up. To validate this concept, the design of the RF front is performed in the CMOS 0.13-${rm mu}hbox{m}$ technology. It includes an LNA, a transconductance stage, and the detector formed by a fully integrated $LC$ -NMOS oscillator. This circuit consumes less than 10 mA for an RF gain above 50 dB and a 1-GHz-wide input signal bandwidth. The measured sensitivity is $-99 hbox{dBm}$ at $10^{-3}$ for a 1-Mb/s pulse rate for binary modulation.      

超宽带脉冲信号波形失真仿真与分析

超宽带无线信道的频率依赖特性直接影响到超宽带接收机的设计和以脉冲波形为基础的多址技术。本文针对频率依赖特性对超宽带脉冲信号波形产生的影响,分别从相位谱和幅度谱两个方面分析超宽带脉冲信号的相位失真和幅频失真特性,建立了描述脉冲波形失真特性的数学模型。使用该模型对高斯二阶导数脉冲信号的波形失真进行仿真分析,得到了只发生相位响应失真、只发生幅度响应失真、以及同时发生相位—幅度响应失真的脉冲波形。     

An approach to ultrawideband pulse generation and distribution over optical fiber

We propose a novel approach to generating and distributing ultrawideband (UWB) pulse signals over optical fiber. The proposed system consists of a single-wavelength laser source, an electrooptic phase modulator (EOPM), a length of single-mode fiber (SMF), and a photodetector (PD). The combination of the EOPM, the SMF link, and the PD forms an all-optical microwave bandpass filter, which is used to generate a UWB signal with a spectrum meeting the regulation of the Federal Communication Commission. Gaussian doublet pulses are obtained at the receiver front-end, which can provide several gigahertz bandwidths for applications in high-bit-rate UWB wireless communications. Experimental results measured in both temporal and frequency domains are presented.     

Performance of a Crossed Exponentially Tapered Slot Antenna for UWB Systems

A compact printed antenna is described that exhibits adequate transient performance for ultrawideband (UWB) applications and it is further adequate for polarization diversity schemes. The antenna is based on an original combination of two crossed exponentially tapered slots plus a star-shaped slot to produce a stable radiation pattern with very stable polarization over the 3.1–10.6 GHz FCC assigned band. Results are confirmed with measurements. Figures of merit like output pulse fidelity and time window containing 90% of the transmitted energy are analyzed over the entire solid angle and showed to remain quite stable, in line with envisaged UWB system requirements. Compact dual-antenna arrangements are also analyzed in view of potential use for UWB multiple-input–multiple-output implementations.      

A 6.3-9-GHz CMOS fast settling PLL for MB-OFDM UWB applications

A CMOS phase-locked loop (PLL) which synthesizes frequencies between 6.336 and 8.976 GHz in steps of 528 MHz and settles in approximately 150 ns is presented. The proposed PLL can be employed as a building block for a frequency synthesizer which generates a seven-band hopping carrier for multiband orthogonal frequency division multiplexing (MB-OFDM) ultrawideband (UWB) radio. To achieve fast loop settling, integer-N architecture that operates with 528-MHz reference frequency is implemented and a wideband active-loop filter is integrated. An improved phase-frequency detector (PFD) is proposed for faster loop settling. To reduce reference sidebands, a feedback circuit using replica bias is implemented in the charge pump. I/Q carriers are generated by two cross-coupled LC VCOs. The output current of the charge pump is controlled to compensate for the VCO gain nonlinearity and a programmable frequency divider (12/spl les/N/spl les/17) that reliably operates at 9 GHz is designed. Fabricated in 0.18-/spl mu/m CMOS technology, the PLL consumes 32 mA from a 1.8-V supply and achieves phase noise of -109.6dBc/Hz at 1-MHz offset and spurs of -52 dBc.     

On the UWB system coexistence with GSM900, UMTS/WCDMA, and GPS

This paper evaluates the level of interference caused by different ultra-wideband (UWB) signals to other various radio systems, as well as the performance degradation of UWB systems in the presence of narrowband interference and pulsed jamming. The in-band interference caused by a selection of UWB signals is calculated at GSM900, UMTS/wideband code-division multiple-access (WCDMA), and Global Position System (GPS) frequency bands as a function of the UWB pulsewidth. Several short-pulse waveforms, based on the Gaussian pulse, can be used to generate UWB transmission. The two UWB system concepts studied here are time hopping and direct sequence spread spectrum. Baseband binary pulse amplitude modulation is used as the data modulation scheme. Proper selection of pulse waveform and pulsewidth allows one to avoid some rejected frequency bands up to a certain limit. However, the pulse shape is also intertwined with the data rate demands. If short-pulses are used in UWB communication the high-pass filtered waveforms are preferred according to the results. The use of long pulses, however, favors the generic Gaussian waveform instead. An UWB system suffers most from narrowband systems if the narrowband interference and the nominal center frequency of the UWB signal overlap. This is proved by bit-error rate simulations in an additive white Gaussian noise (AWGN) channel with interference at global system for mobile communication (GSM) and UMTS/WCDMA frequencies.     

A 5-GHz CMOS Frequency Synthesizer With an Injection-Locked Frequency Divider and Differential Switched Capacitors

A phase-locked loop (PLL)-based frequency synthesizer at 5 GHz is designed and fabricated in 0.18-${rm mu}hbox{m}$ CMOS technology. The power consumption of the synthesizer is significantly reduced by using an injection-locked frequency divider (ILFD) as the first frequency divider in the PLL feedback loop. The synthesizer chip consumes 18 mW of power, of which only 3.93 mW is consumed by the voltage-controlled oscillator (VCO) and the ILFD at 1.8-V supply voltage. The VCO has the phase noise of $-$ 104 dBc/Hz at 1-MHz offset and an output tuning range of 740 MHz. The chip size is 1.1 mm $times$ 0.95 mm.      

20 GHz Wavelet Generator Using a Gated Tunnel Diode

We demonstrate the use of a GaAs-AlGaAs gated tunnel diode (GTD) in an ultra-wideband (UWB) wavelet generator. An inductor is integrated to form an oscillator circuit, which is driven by the negative differential conductance property of a GTD. It is demonstrated that as the gate tunes the magnitude of the output conductance, the oscillator may be switched on and off, creating short RF pulses. The shortest pulses generated are 500 ps long, the highest output power for the free running oscillator is $-$4.1 dBm, and the highest oscillation frequency is 22 GHz. Analytical expressions based on the van der Pol equation describing the pulse length and amplitude are presented. This technique is applicable for high frequency impulse radio UWB implementations.      

Analog and Digital Optical Pulse Synthesizers Using Arrayed-Waveguide Gratings for High-Speed Optical Signal Processing

In this paper, analog and digital optical pulse synthesizers using high-resolution arrayed-waveguide gratings (AWG) have been developed. The analog type of optical synthesizer consists of an AWG with an integrated 45deg, curved-surfaced mirror, a 4-f lens system, and an optically addressable spatial light modulator. The effective frequency resolution is 14.5 GHz. A dispersion compensation experiment is successfully carried out and a transform-limited short pulse has been obtained. This digital type of optical synthesizer comprises 30 frequency separated channels with a spacing of 12.5 GHz, where each channel includes an amplitude modulator and a phase modulator. The rectangular-shaped pulse is generated with this pulse synthesizer, together with a 12.5-GHz-spacing, optical frequency comb. The synthesizer can generate an optical pulse with any waveform. Moreover, using periodic characteristics of the pulse synthesizer, a 250-GHz repetition rate pulse train was generated, in combination with an ultrawideband, waveguide type of Fabry-Perot electrooptic modulator.     

Compact, Dual-Polarized UWB-Antenna, Embedded in a Dielectric

A compact dual-polarized antenna is described for ultrawideband (UWB) applications. The main features of the antenna, besides an ultrawidebandwidth are low cross-polarization and small dimensions. The feed of the antenna is based on the tapered slot antennas, enclosed in a dielectric. The new antenna concept, including the feed of the antenna for dual-polarization and its integration, is described in detail. Prototypes are shown and their performances are demonstrated, based on simulation and measurement results in frequency and time domain. The antenna prototype input match is better than $-10~{rm dB}$, a maximal gain of 10.5 dBi and a mean polarization decoupling of approximately 17 dB in the main beam direction in the 3.1–10.6 GHz UWB band are achieved. In the time domain a peak value of 0.4 m/ns, a full width at half maximum of 100 ps and a ringing of 145 ps are measured. With a maximum antenna diameter of 35 mm and 53 mm length this new antenna is also suited for UWB antenna arrays.      

Performance evaluation of non‐Gaussian channel estimation techniques on ultrawideband impulse radio channels

We study the problem of adaptive channel estimation for a multipath channel on an ultrawideband (UWB) impulse radio (IR) system. The purpose of the work is to demonstrate that the statistical characteristics of the UWB‐IR environment are strongly non‐Gaussian and that as a result, non‐Gaussian signal processing techniques are both efficient and powerful in a UWB‐IR environment. The multipath channel estimation problem has been chosen as an illustrative example because UWB‐IR systems often operate in complex multipath environments. We study both blind and training‐based estimation techniques and demonstrate that even simple non‐Gaussian strategies can achieve significant performance improvement when compared to more common second‐order estimation techniques. Copyright © 2006 John Wiley & Sons, Ltd.