Bandwidth Expansion Technique Research Articles

A Highly Integrated C-Band Feedback Resistor Transceiver Front-End Based on Inductive Resonance and Bandwidth Expansion Techniques.

This paper presents a highly integrated C-band RF transceiver front-end design consisting of two Single Pole Double Throw (SPDT) transmit/receive (T/R) switches, a Low Noise Amplifier (LNA), and a Power Amplifier (PA) for Ultra-Wideband (UWB) positioning system applications. When fabricated using a 0.25 μm GaAs pseudomorphic high electron mobility transistor (pHEMT) process, the switch is optimized for system isolation and stability using inductive resonance techniques. The transceiver front-end achieves overall bandwidth expansion as well as the flat noise in receive mode using the bandwidth expansion technique. The results show that the front-end modules (FEM) have a typical gain of 22 dB in transmit mode, 18 dB in receive mode, and 2 dB noise in the 4.5-8 GHz band, with a chip area of 1.56 × 1.46 mm2. Based on the available literature, it is known that the proposed circuit is the most highly integrated C-band RF transceiver front-end design for UWB applications in the same process.

A 10-Gb/s low-power inverter-based optical receiver front-end in 0.13-[formula omitted] CMOS process

In the design of CMOS optical receivers, it is challenging to compromise the bandwidth, noise, and gain of the transimpedance amplifier (TIA). The inverter-based cascaded structure is often used in TIA designs. However, the traditional 3-stage TIA needs bandwidth expansion techniques to get good performance. In the designed front-end, we propose a 5-stage cascaded TIA that achieves performance improvement without using bandwidth expansion technique. Besides, the stability of the main amplifier (MA) is improved by adopting a feed-forward compensation technique. Designed in a 0.13-μm CMOS process, the proposed front-end exhibits a bandwidth of 8.9 GHz, a transimpedance gain of 123.5 dB Ω and an average input-referred noise of 12.2 pA/Hz. The whole circuit consumed 19.1 mW from mixed input of 1 V and 1.5 V supply voltages.

Analysis and Design of a 2-40.5 GHz Low Noise Amplifier With Multiple Bandwidth Expansion Techniques

This paper analyzes the main factors limiting the bandwidth expansion of low-noise amplifiers (LNA) and designs a broadband LNA with a bandwidth of 2-40.5 GHz. The LNA is designed using multiple bandwidth expansion methods, including cascode, resistance feedback, and cascode Darlington amplifier. The amplitude-frequency characteristics and bandwidth expansion principle of the three structures are studied theoretically based on the small-signal equivalent circuit model. Thanks to these techniques, a three-stage LNA is designed in a 0.15-μm GaAs pseudomorphic high-electron-mobility (pHEMT) process. The measured results show that the designed LNA achieves an average gain of 21.6 dB in 2-40.5 GHz while maintaining a noise figure (NF) below 3.6 dB. The measured output 1-dB gain compression point (OP1 dB) is from 4.5 to 12.8 dBm and the input/output return loss are better than 5 dB. The chip area is only 1.57 mm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> , including input and output test pads.

LED nonlinearity compensation and bandwidth expansion techniques in visible light communication

Visible light communication (VLC) is a promising technology that complements existing wireless communication networks to provide high-speed, low-latency, and multi-device access. With the high-performance code modulation technology of traditional wireless communication, various physical layer communication technologies adapted to VLC systems have been designed and implemented. Different from traditional radio frequency (RF) communication, VLC uses LED as the signal source. The modulation of LED is easy to produce nonlinear distortion and the modulation bandwidth is limited. It has become the technical bottleneck of VLC high-speed communication. In view of the challenges of these two aspects, taking white LED as the starting point, this paper expounds that white LED can effectively balance the characteristics of illumination and communication, summarizes and classifies various techniques of nonlinear distortion compensation and extended modulation bandwidth. Finally, this paper proposes open research issues such as LED package materials and processes, new Micro-LED device research, light source layout design, and intercode interference cancellation technology are expected to improve the performance of visible light communication systems.

Flat Bandwidth Expansion for Spin-Valve GMR Magnetic Field Sensors

Flat Bandwidth Expansion for Spin-Valve GMR Magnetic Field Sensors

Improving Thin Bed Identification in Sarawak Basin Field using Short Time Fourier Transform Half Cepstrum (STFTHC) method

In delineating complex subsurface geological feature, broad band of frequencies are needed to unveil the often hidden features of hydrocarbon basin such as thin bedding. The ability to resolve thin geological horizon on seismic data is recognized to be a fundamental importance for hydrocarbon exploration, seismic interpretation and reserve prediction. For thin bedding, high frequency content is needed to enable tuning, which can be done by applying the band width extension technique. This paper shows an application of Short Time Fourier Transform Half Cepstrum (STFTHC) method, a frequency bandwidth expansion technique for non-stationary seismic signal in increasing the temporal resolution to uncover thin beds and improve characterization of the basin. A wedge model and synthetic seismic data is used to quantify the algorithm as well as real data from Sarawak basin were used to show the effectiveness of this method in enhancing the resolution.

Analysis on spectral regrowth of chirp bandwidth expansion technique in high‐resolution SAR system

AbstractThis article presents an analysis of the root causes of the spectral regrowth due to the higher‐order intermodulation in a chirp bandwidth expansion scheme using a single‐sideband modulator and frequency multipliers. The spectral regrowth of synthetic aperture radar waveform was reduced by minimizing the gain and phase imbalances between the I and the Q channels. Further, the gain and phase imbalance requirements were defined on the basis of the evaluation of the impulse response function. The 150‐MHz bandwidth of a chirp signal at 2.4 GHz was expanded to 600 MHz at 9.6 GHz. By adjusting the dc offset and the gain imbalance between the I and the Q channels, the carrier level was reduced from −28.7 to −53.4 dBm and the sidelobe levels caused by the spectral regrowth were reduced by approximately 8–9 dB. © 2014 Wiley Periodicals, Inc. Microwave Opt Technol Lett 56:400–404, 2014

A wideband amplifier topology based on positive capacitive feedback

We propose a novel bandwidth expansion technique for cascode amplifiers, that exploits positive capacitive feedback (PCF) applied to the cascade of common base and common collector stages to increase the overall amplification at high frequencies. The resulting amplifier has a nearly unchanged input impedance, that we enhance introducing a second PCF loop. We present an ac model of the topology to better understand the behavior of the proposed technique and to compare it with other PCF-based amplifiers. Simulations, carried out using a 230GHz-fT SiGe technology, have shown a 40% bandwidth extension rate with respect to a simple cascode differential pair when a 50Ω source resistance is used, and up to 59% for a 200Ω source resistance. This is a 15–20% more than what can be achieved with other PCF techniques in the literature. The proposed topology is robust against process variations, and retains its advantages when accurate layout parasitics are taken into account.

An Inverter-Based Wideband Low-Noise Amplifier in 40 nm Complementary Metal Oxide Semiconductor

Multistandard RF chips have been highly demanded for multipurpose wireless applications. However, in RF circuits, a low-noise amplifier (LNA) plays an important role in determining the receiver's performance. In this paper, we present a scalable wideband LNA based on complementary metal oxide semiconductor (CMOS) inverters, employing two bandwidth expansion techniques to achieve a large bandwidth without using inductors. Fabricated by the 40 nm CMOS process, the LNA attains 0.1–8.0 GHz of flat bandwidth with S21=17.5 dB and S11≤-10 dB. The minimum NF measured is 5.1 dB and the power consumption is 14.3 mW at 1.3 V. The LNA core circuit is as small as 0.001 mm2 since no large passive device is used. A study of LNA scalability has been conducted by comparing the performances of circuits with the same topology fabricated by the 65, 90, and 180 nm CMOS processes.

An Inverter-Based Wideband Low-Noise Amplifier in 40 nm Complementary Metal Oxide Semiconductor

Multistandard RF chips have been highly demanded for multipurpose wireless applications. However, in RF circuits, a low-noise amplifier (LNA) plays an important role in determining the receiver's performance. In this paper, we present a scalable wideband LNA based on complementary metal oxide semiconductor (CMOS) inverters, employing two bandwidth expansion techniques to achieve a large bandwidth without using inductors. Fabricated by the 40 nm CMOS process, the LNA attains 0.1–8.0 GHz of flat bandwidth with S21=17.5 dB and S11≤-10 dB. The minimum NF measured is 5.1 dB and the power consumption is 14.3 mW at 1.3 V. The LNA core circuit is as small as 0.001 mm2 since no large passive device is used. A study of LNA scalability has been conducted by comparing the performances of circuits with the same topology fabricated by the 65, 90, and 180 nm CMOS processes.

0.1-nm narrow bandwidth transmission of a 2.5-Gb/s spectrum-sliced incoherent light channel using an all-optical bandwidth expansion technique at the receiver

We introduce a new all-optical technique to transmit a spectrum-sliced incoherent channel with its optical bandwidth smaller than the conventional limit. As a demonstration, we reduce the optical bandwidth to only 0.1 nm for the 2.5-Gb/s incoherent channel transmission. Even though the signal-to-noise ratio (SNR) is poor during the transmission, sufficient SNR can be obtained through the intrachannel four-wave mixing at the receiver. With this slim bandwidth transmission technique, the maximum number of spectrum-sliced wavelength-division-multiplexed channels can be increased greatly and the dispersion penalty can be reduced simultaneously.

Expansion of the spectral bandwidth by spatial and chemical shift selective saturation in high-speed magnetic resonance spectroscopic imaging.

A new spectral bandwidth expansion technique for high-speed magnetic resonance spectroscopic imaging (MRSI) based on an echo-planar technique is presented. This expansion can be achieved by spatial and chemical shift selective saturation without increasing the total measurement time. In addition, displacement along the slice-select direction due to chemical-shift differences between the measured compounds is also suppressed. Experimental results are shown using a phantom consisting of benzene and acetone. High spatial resolution (1 x 1 mm2) and wide spectral bandwidth (1.5-1.8 kHz; the effective spectral bandwidth has been doubled) are obtained without the displacement along the slice-select direction.

A Self‐Routing Packet Network Via Optical Processing of the Header

AbstractThe speed limitations of optoelectronic conversions and electronic signal processing for routing control in a packet network restrict the usable bandwidth of a fiber optic channel to well below its full potential. By keeping the signal in optical form and using optical signal processing, it is possible to remove the electronic bottleneck and utilize the untapped bandwidth of fiber optics. Furthermore, fiber optics facilitates the use of bandwidth expansion techniques, such as wavelength division multiplexing, to simplify network design.To allow multiple users access to a high speed optical channel, a new scheme, given the name code‐division header recognition (CDHR), is devised that uses both frequency ‐ and time‐domain bandwidth expansion as well as optical signal processing. An encoded destination address for a data packet is transmitted on a low speed subchannel at a different wavelength from a high speed main channel and optical delay‐line correlators are used for packet routing. The CDHR receivers are used to form a ring network which is then analyzed at the physical layer and the data link layer, specifically the media access control, of tiie OSI network model.

FIBER OPTICS, MICROWAVE, AND COAXIAL TRANSMISSION TECHNIQUES

A comparison study on the three techniques has been done. The study is applied to a particular digital communication link of 280 km length and of 34 M bit/s transmission capacity. It is found that the fiber optic systems are inherently noiser than the others, and the available system gain is much less than it for the microwave and coaxial systems. However, the bandwidth advantage of fiber optics can be utilized through bandwidth expansion techniques to overcome the noise disadvantages. The low loss advantage allows using longer repreater span for fiber optic systems. The study showed that the optical system is less complex, and the coaxial one comes in the second rank. The estimate cost of the particular link gave that the optical fiber system is the least expensive one, whereas using the coaxial cable led to the most expensive system. For the proposed link, the estimated establishment time for microwave does not exceed 10% over the time needed for the other techniques.

A comparison of lightwave, microwave, and coaxial transmission technologies

The relative performance, complexity, and cost for three digital transmission technologies-microwave, coaxial, and lightwaveare compared from the point of view of the lightwave technologist. It is found that lightwave systems are inherently noisier than the others. However, its bandwidth advantage can be exploited through bandwidth expansion techniques to overcome the noise disadvantage. It is further found that lightwave systems are potentially less complex than their radio and wireline counterparts given the advancements expected in the near future. Lastly, it is found that present-day lightwave systems can be less costly than the other technologies. Furthermore, it is found that anticipated near-term improvements to the technology will make lightwave systems even more attractive from the cost point of view. It is concluded that digital lightwave and microwave systems will continue to grow in usage-each has its own unique advantages relative to the other-and that digital coaxial systems will decline in usage.

A Comparison of Lightwave, Microwave, and Coaxial Transmission Technologies

The relative performance, complexity, and cost for three digital transmission technologies-microwave, coaxial, and lightwave- are compared from the point of view of the lightwave technologist. It is found that lightwave systems are inherently noisier than the others. However, its bandwidth advantage can be exploited through bandwidth expansion techniques to overcome the noise disadvantage. It is further found that lightwave systems are potentially less complex than their radio and wireline counterparts given the advancements expected in the near future. Lastly, it is found that present-day lightwave systems can be less costly than the other technologies. Furthermore, it is found that anticipated near-term improvements to the technology will make lightwave systems even more attractive from the cost point of view. It is concluded that digital lightwave and microwave systems will continue to grow in usage-each has its own unique advantages relative to the other-and that digital coaxial systems will decline in usage.