Ultra-wideband System Applications Research Articles

Miniaturisation of UWB triangular slot antenna by the use of DRAF

In this study, the dual-reverse-arrow fractal (DRAF) geometry is applied to the sides of a slotted microstrip triangular patch to design ultra-wideband (UWB) antenna with a coplanar waveguide (CPW) feed with and without notch bands. It is shown that the proposed DRAF geometry has the capability of both reducing the antenna size, but without decreasing its bandwidth and also maintaining the other antenna radiation characteristics. It is shown that the antenna is miniaturised by 40% compared with the simple triangular patch. Furthermore, in order to prevent any interference of the proposed antenna with the wireless system of high performance radio LAN (HiperLAN)/2, a notch band is created by cutting two similar slots in the T-shaped CPW-feed. Such an antenna has applications in UWB systems. Two prototype DRAF antennas are fabricated and measured, which verify its desirable features.

Compact Differential Band-Notched Stepped-Slot UWB-MIMO Antenna With Common-Mode Suppression

A compact printed differential multiple-input–multiple-output (MIMO) antenna is presented for ultrawideband system applications with band-notched characteristic. The proposed MIMO antenna element consists of a differential U-shaped microstrip feedline and a stepped-shaped slot, printed on the bottom and top of the substrate, respectively. A half-wavelength resonant stub embedded in the stepped-shaped slot is exploited to obtain notched band, whose center frequency can be adjusted by the length of the stub. The staged slots among antenna elements are introduced to enhance the differential isolation. The final antenna has a compact size of $44 \times 44\; \text{mm}^{2}$ . Measured results show that the proposed MIMO antenna achieves −10-dB impedance bandwidth from 2.95 to 10.8 GHz, isolation better than 15.5 dB over the whole operating band, and a notched band from 5.10 to 5.95 GHz.

A Novel IBF and Its Application in Ultra-Wideband Systems

This paper proposes a new interleaving rule, with which a new IBF (IBF, intertwined bridge function) is generated. Not only does the new intertwined bridge function have a zero correlation zone, but also its cross-correlation performance is ideal. An ultra-wideband system is introduced, which uses the intertwined bridge functions as the spreading code. The sequence of interleaved bridge function with zero autocorrelation bridge area and zero cross-correlation zones can better reduce multiple access interference and multipath interference. It is shown by the simulation results that the ultra-wideband systems using the interleaved bridge function as the spreading sequence have better error rate performance.

A highly miniaturized LTCC dual-band UWB filter using independent transmission zeros and lowpass filters

In this paper, a compact dual-band ultra-wideband (UWB) filter has been newly designed and fabricated for 3.1–4.75GHz and 6.0–8.5GHz UWB system applications by embedding all passive lumped elements into low temperature co-fired ceramic (LTCC) substrate. In order to reduce its size/volume and prevent parasitic electromagnetic (EM) coupling between the embedded passive elements, it was newly designed by using a modified 3rd order Chebyshev filter topology and J-inverter transformation technology. Moreover, in order to completely reject the wireless local area network (WLAN) bands of 2.4GHz and 5.15GHz, an independent transmission zeros technology was applied. For forming the higher passband, lowpass filters were also applied with two LC resonant circuits by using roll-off characteristics by independent transmission zeros. The measured insertion losses in the lower and upper passbands were better than 2.5 and 2.3dB, respectively. Return loss and group delay were better than 8dB and 0.61ns, respectively in all the passbands. Independent transmission zeros that occurred at 5.17 and 5.42GHz provided suppression of 22dB at the WLAN band. The size/volume of the fabricated LTCC dual-band UWB filter was 3.65×2.35×0.65 (H)mm3.

Impact of channel models on compressed sensing recovery algorithms‐based ultra‐wideband channel estimation

Multipath arrivals in an ultra-wideband (UWB) channel have long time intervals between clusters and rays where the signal takes on zero or negligible values. It is precisely this signal sparsity of the impulse response of the UWB channel that is suitable for the application of compressed sensing (CS) theory. However, these multipath arrivals mainly depend on the channel models that generate different sparse levels (low-sparse or high-sparse) of channels according to which, the authors have analysed and chosen the best recovery algorithms which are suitable for the sparse level for each type of channel model. Criteria for evaluating the algorithms are based on computational complexity, ability to reduce the sampling rate and processing time. Besides, the results of this work are an open topic for further research aimed at creating an optimal algorithm specially for application of CS-based UWB systems.

A low-voltage ultra-wideband down-conversion mixer with improved power conversion gain

This article presents a wideband mixer using a TSMC 0.18 µm complementary metal-oxide semiconductor technology process for ultra-wideband (UWB) system applications. The measured 3-dB radio frequency (RF) bandwidth is from 3 to 8.4 GHz with an intermediate frequency of 10 MHz. The measurement results of the proposed mixer achieve 8.1 dB average power conversion gain −5 dBm input third-order intercept point (IIP3) at 7.4 GHz and 12.4–13.3 dB double side band noise figure. The total dc power consumption of this mixer including output buffers is 3.18 mW from a 1 V supply voltage. The output current buffer consumption is about 2.26 mW with an excellent local oscillator-RF isolation of up to 40 dB at 5 GHz. The article presents a mixer topology that is greatly suitable for low-power operation in UWB system applications.

A Novel Analog Broadband RF Predistortion Circuit to Linearize Electro-Absorption Modulators in Multiband OFDM Radio-Over-Fiber Systems

We propose and demonstrate a novel and simple predistortion circuit using reflective antiparallel diodes for linearization of electro-absorption modulators (EAMs) in multiband orthogonal frequency-division multiplexing (MB-OFDM) ultra-wideband (UWB) radio-over-fiber systems for UWB signals from 3.1 to 4.8 GHz. In this novel predistortion circuit, neither amplifiers, nor phase shifters are used, while only two antiparallel connected diodes are used, and the predistortion signal is adjusted by tuning the diodes' dc-bias current. The simple architecture makes the circuit cost effective and suitable for UWB system applications. By adding the predistortion circuit before the EAM, more than 7-dB suppression in third-order intermodulation distortion and 11-dB improvement in spurious-free dynamic range are achieved over the frequency range of 3.1-4.8 GHz, i.e., bandgroup 1 of MB-OFDM UWB. Correspondingly, 1-dB improvement in error vector magnitude is obtained experimentally when the designed predistortion circuit is used.

A low-voltage high-linearity ultra-wideband down-conversion mixer in 0.18-μm CMOS technology

This paper presents a wideband mixer chip covering the frequency range from 3.4 to 6.8GHz using TSMC 0.18μm CMOS technology. The linearity can be improved using multiple-gated-transistors (MGTR) topology. The measured 3-dB RF frequency bandwidth is from 3.1 to 6.8GHz with an IF of 10MHz. The measured results of the proposed mixer achieve 7.2–4.3dB power conversion gain and 2–3dBm input third-order intercept point (IIP3), and the total dc power consumption of this mixer including output buffers is 2.9mW from a 1V supply voltage. The current output buffer is about 2.17mW, and the excellent LO–RF isolation achieved up to 54dB at 5GHz. The paper presents a mixer topology that is very suitable for low-power in ultra-wideband system applications.

Miniature hook-shaped monopole antenna for UWB applications

A miniature hook-shaped monopole antenna is presented for ultra-wideband (UWB) applications. This microstrip-fed antenna consists of a multi-branch radiator with overall dimensions of only 10 (L)×10 (W)×1.6 (H)mm to be easily embedded in various portable devices and with a wide impedance bandwidth covering 3–10.7 GHz. Omnidirectional radiation patterns with appreciable gain across the operating band can be obtained. Reasonably good transmission characteristic and group delay also show that the proposed broadband antenna is well suited for applications in UWB systems.

A Low Power Consumption and Wide-Band Input Matching CMOS Active Balun for UWB System Applications

This work presents an ultra-wideband (UWB) active balun (balanced-to-unbalanced) with current-reused technique for wideband input matching and low power consumption by using standard 0.18 μm CMOS processes. The proposed circuit, using parallel common gate and common source structure, can efficiently improve the input-matching bandwidth for up to 10 GHz. Besides, the proposed circuit has good gain imbalance and phase imbalance from 3.1 GHz to 10.6 GHz. The proposed active balun achieved 4 ± 1 dB gain with amplitude (gain) imbalances less than 0.5 dB, phase differences of 180° ± 2°, 11.7 mW power consumption at 1.8 V supply voltage from 3.1 GHz to 10.6 GHz, and the chip size including pads is 0.76 × 0.73 mm2.

Planar monopole antenna employing back-plane ladder-shaped resonant structure for ultra-wideband performance

This study describes a microstrip-fed planar monopole antenna incorporating a resonant structure in the form of a ladder-shape, which is etched on its back-plane. The radiation element of the antenna comprises a simple rectangular-shaped patch. The feature that makes the antenna different from a traditional monopole antenna is the resonant structure's configuration. The resonant structure has an effect of transforming the monopole antenna into an ultra-wideband (UWB) antenna. The prototype antenna's performance was verified through simulations and measurements. The antenna's dimensions are 22×22 mm2 and its measured impedance bandwidth (S11<−10 dB) stretches across approximately more than 17 GHz, between 2.7 and 20 GHz. The proposed antenna's performance extends significantly beyond the UWB frequency band as defined by the Federal Communications Commission, and its omnidirectional E- and H-plane radiation patterns are stable across its bandwidth. The results presented show that the proposed technique can be applied directly to the design of planar monopole antennas. The antenna exhibits UWB behaviour with near omnidirectional characteristics and radiation efficiency >80%. Additional features that make this antenna attractive and viable for modern UWB system applications are its simple configuration, low profile, compactness and low fabrication cost.

A CPW‐FED circularly polarized antenna for lower ultra‐wideband applications

AbstractA novel design of circularly polarized square slot antenna fed by a coplanar waveguide for lower ultra‐wideband (UWB) application is presented. Circular polarization is achieved by protruding a truncated corner and a grounded inverted‐L strip at two opposite corners, respectively. The antenna is investigated both in the frequency and time domains. The results show that its measured 10‐dB return loss bandwidth is from 2.7–5.0 GHz and 3‐dB axial ratio bandwidth varies from 3.5 to 4.8 GHz, whereas the size is just 35 mm × 35 mm. The proposed antenna is suitable for lower UWB system (3.4–4.8 GHz) applications in Singapore. © 2009 Wiley Periodicals, Inc. Microwave Opt Technol Lett 51: 2365–2369, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.24629

Noncoherent ultra-wideband systems

The need for low-complexity devices with low-power consumption motivates the application of suboptimal noncoherent ultra-wideband (UWB) receivers. This article provides an overview of the state of the art of recent research activities in this field. It introduces energy detection and autocorrelation receiver front ends with a focus on architectures that perform the initial signal processing tasks in the analog domain, such that the receiver does not need to sample the UWB received signals at Nyquist rate. Common signaling and multiple access schemes are reviewed for both front ends. An elaborate section illustrates various performance tradeoffs to highlight preferred system choices. Practical issues are discussed, including, for low-data-rate schemes, the allowed power allocation per pulse according to the regulator's ruling and the estimated power consumption of a receiver chip. A large part is devoted to signal processing steps needed in a digital receiver. It starts with synchronization and time-of-arrival estimation schemes, introduces studies about the narrowband interference problem, and describes solutions for high-data-rate and multiple access communications. Drastic advantages concerning complexity and robustness justify the application of noncoherent UWB systems, particularly for low-data-rate systems.

Low-power wide-locking-range injection-locked frequency divider for OFDM UWB systems

This paper describes a divide-by-two injection-locked frequency divider (ILFD) for frequency synthesizers as used in multiband orthogonal frequency division multiplexing (OFDM) ultra-wideband (UWB) systems. By means of dual-injection technique and other conventional tuning techniques, such as DCCA and varactor tuning, the divider demonstrates a wide locking range while consuming much less power. The chip was fabricated in the Jazz 0.18 μm RF CMOS process. The measurement results show that the divider achieves a locking range of 4.85 GHz (6.23 to 11.08 GHz) at an input power of 8 dBm. The core circuit without the test buffer consumes only 3.7 mA from a 1.8 V power supply and has a die area of 0.38 × 0.28 mm2. The wide locking range combined with low power consumption makes the ILFD suitable for its application in UWB systems.

Analysis Techniques for the Power Spectral Density Estimation of Convolutionally Coded Impulse Radio UWB Signals Subject to Attenuation and Timing Jitter

A method for the spectral analysis of convolutionally coded Markov-driven impulse radio (IR)-based ultrawideband (UWB) systems is introduced. Example applications in UWB systems include the study of pulse position modulation (PPM), pulse-amplitude modulation (PAM), biorthogonal modulation, and pulse-shape modulation combined with periodic (e.g., pseudorandom)/random time-hopping (TH), as well as periodic/random direct-sequence (DS) multiplication. The effects of random jitter and pulse attenuation are considered in this analysis. The final result allows simple examination of the power spectral density (PSD) of such signals. This result clearly delimitates the relative contributions of parameters that allow enhanced design of UWB systems. Application examples are presented for a new convolutional encoder, providing a spectral-line-free PSD for quaternary biorthogonal (PAM/PPM) modulation IR UWB systems.

A compact UWB microstrip monopole antenna, with Periodically Defected Ground Structure

This paper describes a microstrip-fed planar monopole antenna using Defected Ground Structure (DGS) technique. In addition, we have applied partial technique in the rectangular radiating element to achieve an ultra wide band characteristic for impedance matching. The simulated impedance band width of this antenna for S11 ≤ -10dB is about 6GHz, from 3.9GHz up to 10.8GHz. The proposed antenna's performance approximately covers the band width of ultra wide band as defined by FCC. Additional features that make this antenna attractive and viable for modern ultra-wideband system applications are its simple configuration, low profile, compactness, and low fabrication cost.

A high‐performance 1–7 GHz UWB LNA using standard 0.18 μM CMOS technology

AbstractIn this article, we demonstrate a high‐performance 1‐ to 7‐GHz ultra‐wideband (UWB) low‐noise amplifier (LNA) for UWB system applications implemented in a standard 0.18 μm CMOS technology. This LNA can also be applied to 1.8/1.9‐GHz‐band GSM systems, and 2.4/4.9/5.2/5.7‐GHz‐band WLAN systems. The LNA consists of two cascaded stages, in which the pole of the first stage is cancelled by the zero of the second stage over the 1–7 GHz of interest. In addition, the inductive peaking technique is adopted in the second stage for bandwidth enhancement. This LNA achieved input return loss (S11) of −10 to −15.3 dB, output return loss (S22) of −19.4 to −10.3 dB, voltage gain (AV) of 13.3 to 14.6 dB, reverse isolation (S12) of −37.7 to −27.1 dB over the 1‐ to 7‐GHz band of interest. The measured noise figure (NF) was 4.86–4.35 dB over the 2–8.5 GHz band. The measured 1‐dB compression point (P1dB) and third‐order inter‐modulation point (IIP3) were −13.5 dBm and −3 dBm, respectively, at 6 GHz. The chip area was only 500 μm × 582 μm excluding the test pads. This LNA drained 10.4 mA current at supply voltage of 1.5 V, i.e. it only consumed 15.6 mW power. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 2458–2462, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.22780

A Low Power Folded Mixer for UWB System Applications in 0.18-$\mu$m CMOS Technology

This letter presents a wideband mixer using a commercial 0.18-mum CMOS technology process for ultra-wideband (UWB) system applications. To achieve wideband frequency response and low dc power consumption for UWB system applications, the folded approach is utilized to reduce supply voltage as well as dc power consumption, and wideband input matching network is used to achieve wideband frequency response. The measured results show that the proposed mixer demonstrates a wideband frequency response from 0.2 to 16GHz with a conversion gain of better than 5.3dB. The dc power consumption is 15mW under a supply voltage of 1.8V, with a compact size of 0.68mmtimes0.65mm

On the Development of an Integrated CMOS-Based UWB Tunable-Pulse Transmit Module

A novel low-cost low-power fully integrated tunable transmit module composed of a tunable CMOS monocycle pulse generator and compact uniplanar antenna was designed, built, and tested for ultra-wideband (UWB) impulse systems. The CMOS tunable pulse generator integrates a tuning delay circuit, square-wave generator, impulse-forming circuit, and pulse-shaping circuit in a single chip using a standard low-cost 0.25-mum CMOS process. It can generate a monocycle pulse and Gaussian-type impulse (without the pulse-shaping circuitry) signals with tunable pulse duration. A compact uniplanar UWB antenna was also developed and integrated directly with the CMOS pulse generator chip to form the complete integrated tunable UWB transmit module. Measured results show that the CMOS tunable pulse generator can produce a 0.3-0.6-V peak-to-peak monocycle pulse with 140-350-ps tunable pulse duration and a 0.5-1.3-V peak-to-peak impulse signal with 100-300-ps tunable pulse-duration, and the uniplanar antenna has less than a 18-dB return loss and is suitable for transmitting/receiving UWB time-domain impulse signals covering the entire UWB bandwidth of 3.1-10.6 GHz. Good agreement between measured and calculated performance is also achieved. The UWB transmit module was experimentally characterized and its performance is verified. This UWB module finds applications in various time-domain UWB systems including wireless communications and radar

Analysis and design of an ultra-wideband low-noise amplifier using resistive feedback in SiGe HBT technology

We present the analysis and design of an inductorless wide-band SiGe heterojunction bipolar transistor low-noise amplifier (LNA) using a resistive feedback scheme for application in ultra-wideband systems. Multiple feedback loops enable sufficient gain and low noise figure, and is competitive with conventional narrow-band cascode LNAs using an emitter degeneration inductor. Measurement results show 20-dB gain with 1-dB variation over 3-10 GHz, and a matched input and output with less than -10-dB reflection. The minimum noise figure is 3.05 dB at 3 GHz and increases to 4.5 dB at 10 GHz. For the analysis and design of such wide-band amplifiers, analytical expressions describing the basic performance tradeoffs are derived and verified with simulation and measurements. General design procedures are also given in this paper in order to better understand the roles of the various critical components in the amplifier.