A large class of binary ZCZ sequence families constructed by period doubling

In an Approximately Synchronized Code Division Multiple Access （AS-CDMA） communication system, a family with large number of Zero Correlation Zone （ZCZ） sequences is desired, which can satisfy the rapid increase of users. This paper presents a method to generate a （2L,2M, ZCZ＇）-ZCZ sequence family from an original （L,M,ZCZ）-ZCZ sequence family, where ZCZ＇ = ZCZ if ZCZ is even and ZCZ＇ =ZCZ - 1 if ZCZ is odd. This method can also recursively act on a ZCZ sequence family to construct a series of ZCZ sequence families with large sequence number and zero correlation zone length identical to or one less than that of original ZCZ sequences.     

Modeling Transmission of Microwaves Through Dynamic Vegetation

In this paper, we develop a model for estimating canopy opacity tau for sweet corn. We estimate the refractive index based upon moisture distribution in the corn during different stages of growth. The moisture distribution was observed during two season-long field experiments. We found that the moisture content decreased linearly as the height of the corn increased, with the distribution closer to Gaussian in the fruit region during reproductive stages. The tau obtained from our model was compared to that estimated using a widely used Jackson model. In general, our tau estimates were higher than those obtained using the Jackson model, with a root mean-square difference (rmsd) of up to 0.23 Np between the two models. The tau values were used in a microwave emission model at C-band, and the model estimates of brightness were compared with field observations. We found that the model brightness temperatures matched well with observations, with rmsd values of 5.13 and 4.88 K, using our model and the Jackson model for tau, respectively.     

RF Testing on a Mixed Signal Tester

In this paper, testing of radio frequency (RF) devices with mixed-signal testers is discussed. General purpose automatic test equipment (ATE) will be used. In this paper, a more universal test structure utilizing RF building blocks is proposed. A global positioning system (GPS) device is used as an example to illustrate how to develop the RF test plan with this usage. The test plan developed includes fast, cost-effective and dedicated circuitry.

LLE-based classification algorithm for MMW radar target recognition

In this paper, a new multiclass classification algorithm is proposed based on the idea of Locally Linear Embedding (LLE), to avoid the defect of traditional manifold learning algorithms, which can not deal with new sample points. The algorithm defines an error as a criterion by computing a sample’s reconstruc-tion weight using LLE. Furthermore, the existence and characteristics of low dimensional manifold in range-profile time-frequency information are explored using manifold learning algorithm, aiming at the problem of target recognition about high range resolution MilliMeter-Wave (MMW) radar. The new algo-rithm is applied to radar target recognition. The experiment results show the algorithm is efficient. Com-pared with other classification algorithms, our method improves the recognition precision and the result is not sensitive to input parameters.     

Noncoherent spectral optical CDMA system using 1-D subtracted square codes of all transmitters in one optical line terminal

We propose a family of one-dimensional subtracted square codes in the spectral amplitude coding optical code division multiple access system. The proposed codes perform the subtraction and multiplication operations to give one-to-one mappings function, which produces the code sequences of 1-D subtracted square codes. The proposed structure uses one optical line terminal to produce all of the transmitters. This proposed system overcomes the interference from other simultaneous users, known as multiuser interference, and the cross-correlations suppress the phase-induced intensity noise. In numerical simulations using the proposed 1-D subtracted square codes, we show that 83 simultaneous users can be supported at a bit error rate of \(10^{-9}\). This number of simultaneous users in the proposed system using the 1-D subtracted square codes is superior to that in the other systems using the 1-D M sequence codes, 1-D RSQC codes, and 1-D ESP codes. The proposed system using the 1-D subtracted square codes achieves a data transmission rate of 3.2 Gbps.     

94 GHz down-conversion mixer with gain enhanced Gilbert cell in 90 nm CMOS

This paper introduces an adaptive semiblind background calibration of timing mismatches in a two-channel time-interleaved analog-to-digital converter (TIADC). By injecting a test tone at the frequency of half the overall sampling frequency of TIADC, the timing mismatch between two sub-ADCs can be quickly estimated with great accuracy without affecting the normal operation of the TIADC. The estimated coefficient can then be used in compensation module formed by a fixed structure to calibrate the timing mismatches. Simulation results demonstrate the effectiveness of the proposed estimation and correction technique.     

A New Method Modifying Single Miller Feedforward Frequency Compensation to Drive Large Capacitive Loads: Putting an Attenuator in the Path

A new method to compensate three-stage amplifier to drive large capacitive loads is proposed in this paper. Gain Bandwidth Product is increased due to use an attenuator in the path of miller compensation capacitor. Analysis demonstrates that the gain bandwidth product will be improved significantly without using large compensation capacitor. Using a feedforward path is deployed to control a left half plane zero which is able to cancel out first non-dominant pole. A three stage amplifier is simulated in a 0.18 μm CMOS technology. The purpose of the design is to compensate three-stage amplifier loading 1000 pF capacitive load. The simulated amplifier with a 1000 pF capacitive load is performed in 3.3 MHz gain bandwidth product, and phase margin of 50. The compensation capacitor is reduced extremely compared to conventional nested miller compensation methods. Since transconductance of each stage is not distinct, and it is close to one another; as a result, this method is suitable low power design methodology.     

A 700 MHz laser radar receiver realized in 0.18 μm HV-CMOS

This study presents a CMOS receiver chip realized in 0.18 µm High-Voltage CMOS (HV-CMOS) technology and intended for high precision pulsed time-of-flight laser range finding utilizing high-energy sub-ns laser pulses. The IC chip includes a trans-impedance preamplifier, a post-amplifier and a timing comparator. Timing discrimination is based on leading edge detection and the trailing edge is also discriminated for measuring the width of the pulse. The transimpedance of the channel is 25 kΩ, the uncompensated walk error is 470 ps in the dynamic range of 1:21,000 and the input referred equivalent noise current 450 nA (rms).     

Design and Characterization of a W-Band Folded-Waveguide Slow-Wave Structure

A single-section slow-wave structure for a W-band folded-waveguide traveling-wave tube with operating bandwidth of around 4% was designed for delivering the output power of 50 W at the operating voltage of 13.5 kV and operating beam current of 80 mA. The design was carried out using analytical formulations and 3D electromagnetic simulations. The beam-wave interaction analysis was carried out using large signal Lagrangian analysis and particle-in-cell simulation. The folded-waveguide slow-wave structure along with input-output couplers and RF windows were fabricated. Cold test measurements were carried out for dispersion characteristics of the slow-wave structure and voltage standing-wave ratio and insertion loss characteristics of the RF window. The measured cold circuit parameters show close agreement with the analysis.     

TiN Nanoparticles for Enhanced THz Generation in TDS Systems

By virtue of the surface plasmon resonance effect, plasmonic nanoparticles (NPs) can localize the light field and significantly enhance the performance of some optoelectronic devices. In this work, NPs are employed for an enhanced generation of terahertz radiation from LT-GaAs-based antennas. Therefore, we have prepared plasmonic TiN NPs by direct ultrasonication (ULS) and pulsed laser ablation (PLA) techniques. The zeta potential, particle size, and absorbance were used to characterize the NPs in their colloidal forms in a comparison to commercial Au NPs. A layer of polydispersed titanium nitride (TiN) NPs prepared by PLA and deposited on the surface of an LT-GaAs device shows a significant improvement of terahertz signal generation from these devices with an enhancement of the peak to peak amplitude of 100%.