This paper proposes the combination of adjustable architecture and parameter optimization software, employing a method based on artificial intelligence (AI), to realize an image rejection mixer (IRM) that can enhance its image rejection ratio within a short period of time. The main components of the IRM are 6 Gilbert-cell multipliers. The tail current of each multiplier is adjusted by the optimization software, and the gain and phase characteristics are optimized. This adjustment is conventionally extremely difficult because the 6 tail currents to be adjusted simultaneously are mutually interdependent. In order to execute this adjustment efficiently, we employed a Genetic Algorithm (GA) that is a robust search algorithm that can find optimal parameter settings in a short time. We have successfully developed an IRM chip that has a performance of 71 dB and is suitable for single-chip integration with WCDMA applications.

This paper describes a numerical design procedure of element values of RC polyphase filters with equal minima in stopband and equal ripple in passband. Determination of element values of RC polyphase filters with equal-ripple characteristic have not been solved to the best knowledge of the authors. There found a paper tackling with the problem; however, it can only give sub-optimal solutions via numerical calculation [3]. We propose a numerical element value design procedure for RC polyphase filters with equi-ripple gain in both stopband and passband by using the coefficient matching method. Some design examples are given.

This paper presents a frequency-controllable image rejection mixer in heterodyne architecture for 2 GHz applications based on TSMC 0.18 µm CMOS technology. The designed mixer uses a notch filter to suppress the image signal and allows precise tuning the image frequencies. An image rejection of 20-70 dB is obtained in a 200 MHz of bandwidth. The simulation results show single-side band (SSB) NF is improved 3.7 dB, the voltage conversion gain of 14.7 dB, improved by more than 4 dB. The circuit operates at the supply voltage of 1.8 V, and dissipates 11.34 mW.

A new sub-1-V CMOS bandgap voltage reference without using low-threshold-voltage device is presented in this paper. The new proposed sub-1-V bandgap reference with startup circuit has been successfully verified in a standard 0.25-µm CMOS process, where the occupied silicon area is only 177 µm106 µm. The experimental results have shown that, with the minimum supply voltage of 0.85 V, the output reference voltage is 238.2 mV at room temperature, and the temperature coefficient is 58.1 ppm/ from -10 to 120 without laser trimming. Under the supply voltage of 0.85 V, the average power supply rejection ratio (PSRR) is -33.2 dB at 10 kHz.

This paper is devoted to the problem of force sensorless disturbance rejection in robot manipulators. In the proposed approach, the control system uses position sensor signals and estimated values of external forces, instead of force sensor signals. The estimation process is performed via an adaptive force estimator. Then the estimated force vector is utilized to compensate for the force disturbance effect in order to achieve a better trajectory tracking performance. The force estimation is carried out directly using no environment model. Asymptotical stability of the proposed control system is analyzed by the invariant set and Lyapunov direct method establishing an appropriate theorem. Finally, the performance of the proposed control system is verified using numerical simulation.

A RF front-end chip for a dual-band Global Positioning System (GPS) receiver for L1 and L2 bands is designed using 0.25 µm CMOS technology. All function blocks of the GPS front-end are integrated onto one chip. The low noise amplifier has input matching over a wide frequency range to handle the L1 and L2 bands. This receiver uses a dual-band image-reject mixer with the quadrature mixer sharing a transconductor stage. This configuration enables the RF blocks to be shared with the L1 and L2 bands. The receiver has a chip area of 3.16 mm3.16 mm, and consumes 35 mA at 2.5 V.

Press-induced long-period fiber gratings exhibiting strong core-to-cladding mode coupling were formed in photonic crystal fiber. Only one resonance peak was observed over a 600 nm spectral range and the resonant wavelength was tuned over the whole range by tilting a groove plate before pressing the fiber. The resonant wavelength decreased with increasing periodicity of the grating, which was opposite to the trend of the step-index conventional optical fiber. Meanwhile, the resonant wavelength increased with increasing the ambient refractive index, which was also opposite to that of the conventional optical fiber.

Bayesian combining of confidence measures is proposed for speech recognition. Bayesian combining is achieved by the estimation of joint pdf of confidence feature vector in correct and incorrect hypothesis classes. In addition, the adaptation of a confidence score using the pdf is presented. The proposed methods reduced the classification error rate by 18% from the conventional single feature based confidence scoring method in isolated word Out-of-Vocabulary rejection test.

This letter introduces a pre-rejection technique for wireless channel distorted speech with application to automatic speech recognition (ASR). Based on analysis of distorted speech signals over a wireless communication channel, we propose a method to reject the channel distorted speech with a small computational load. From a number of simulation results, we can discover that the pre-rejection algorithm enhances the robustness of speech recognition operation.

This paper describes the performance improvement of power amplifiers by defected ground structure (DGS). Due to the excellent capability of harmonic rejection and tuning, DGS plays a great role in improving the major nonlinear behaviors of power amplifier such as output power, harmonics, power added efficiency (PAE), and the ratio between the carrier and the third order intermodulation distortion (C/IMD3). In order to verify the improvement of performances by DGS, measured data for a power amplifier, which adopts a 30 Watts LDMOS device for the operation at 2.1-2.2 GHz, are illustrated under several operating bias currents for two cases, i.e., with and without DGS attached. The principle of the improvement is described by the simple Volterra nonlinear transfer functions with the consideration of different operating classes. The obtained improvement of the 30 Watts power amplifier, under 400 mA of IdsQ as an example, includes the reduction in the second and third harmonics by 17 dB and 20 dB, and the increase in output power, PAE, and C/IMD3 by 1.3 Watts, 3.4%, and 4.7 dB, respectively.

A 270 GHz-band image rejection SIS mixer is developed. This mixer employs planer type image rejection configuration and is integrated into a single-chip as in MMIC's at microwave frequency. In order to use sapphire substrate at 270 GHz-band, CPW transmission lines are selected to realize 50-70Ω characteristic impedances. The fabricated MMIC SIS mixer performs 12-24 dB image rejection ratio with 450-780 K noise temperature at 270 GHz.

It have been one open and significant topic for real-time applications to enhance the processing-speed of Boltzmann machines for long time. One effective way of solution of this problem is the augmentation of probability of neurons' state move. In this paper, a novel method, called a rejectionless method, was proposed and introduced into the Boltzmann machines for this augmentation. This method has a feature of independence on the ratio of neurons' state move. The efficiency of this method for speed-up was confirmed with the experiments of TSP and graph problem.

We consider the services of broadcasting short messages via forward signaling channels in wireless cellular networks. In the provision of such services, the negative effect of short messages on the delivery of delay-sensitive control messages must be restricted. On the other hand, it is desirable to accommodate the users' demands for service enhancements involving timeliness and informativeness. As a way to resolve such conflicting arguments, we present a generic scheme in which a short message may be rejected or removed according to the buffer occupancy at the base station and is split into a number of segments for the transmission across a forward signaling channel. However, the rejection, removal and segmentation exhibit a trade-off among several facets of service enhancements. Thus, for a quantitative evaluation of the scheme and efficient optimization of design parameters, we develop an analytical method to calculate the moments of delay times experienced by control and short messages at a base station. Using the analytical method, we investigate the delay and loss performance of control and short messages with respect to the message load and short message length.

In this paper, we present a method to analyze the steady-state performance of a complex coefficient adaptive IIR notch filter which is useful for the rejection of multiple narrow-band interferences from broad-band signals in quadrature phase shift keying (QPSK) spread-spectrum communication systems. The adaptive notch filter based on the simplified gradient algorithm is considered. Analytical expressions have been developed for the conditional mean and variance of notch filter output. The signal-to-noise ratio improvement factor is also obtained from which the validity of the use of the notch filter can be concluded. Finally, the results of computer simulations are shown which confirm the theoretical predictions.

In this paper, we discuss an IF image rejection system with variable bandwidth and center frequency. The system is consists of a pair of frequency mixers multiplied by the complex sinusoid and a complex analog filter. By employing the complex leapfrog structure using OTA-C configuration and the frequency transformation from the normalized LPF, the proposed system is capable of variable bandwidth and center frequency characteristics. SPICE simulations result more than 43 [dB] image rejection is achieved for 6 [kHz] and 12 [kHz] bandwidths at 50 [kHz] IF.

A 1-V 2-GHz receiver that exhibits an image rejection of 49 dB is described. It consists of a low-noise amplifier, a quadrature mixer and on-chip polyphase filters, and was fabricated by 0.2-µm fully depleted CMOS/SIMOX technology. The quadrature mixer employs an LC-tuned folded structure with a common RF input for I and Q channels. This enables 1-V operation, suppresses phase errors in LO signals, and improves the image-rejection performance by about 15-dB compared to a conventional quadrature architecture. The current source of the single-to-balance converter at the mixer input consists of a transistor and an LC tank in a cascode configuration. This enhances its output impedance and improves its common-mode-rejection ratio (CMRR) and the IIP2 characteristics of the receiver. The chip consumes 12 mW with 1-V power supply. The receiver provides an NF of 10 dB with an IIP3 of -15.8 dBm and IIP2 of 12.3 dBm.

Various shadows are one of main factors that cause errors in vision based vehicle detection. In this paper, two simple methods, land mark based method and BS & Edge method, are proposed for vehicle detection and shadow rejection. In the experiments, the accuracy of vehicle detection is higher than 98%, during which the shadows arisen from roadside buildings grew considerably. Based on these two methods, vehicle counting, tracking, classification, and speed estimation are achieved so that real-time traffic parameters concerning traffic flow can be extracted to describe the load of each lane.

In an ideal fiber grating having a uniform refractive index modulation, the reflection or the transmission spectrum is symmetric with equal amount of side lobes on both sides of the resonant wavelength of the fiber grating. It is observed that a long-period fiber grating made by a non-uniform UV laser beam through a uniform amplitude mask has an asymmetric transmission spectrum. The asymmetric characteristic is explained with Mach-Zehnder effect in the long-period fiber grating. The non-uniform UV laser beam makes also a non-uniform index modulation along the fiber core. Therefore, a beam coupled to a cladding mode at a section of the grating can be re-coupled to the core mode after passing a certain distance. The re-coupled beam makes Mach-Zehnder-like interference with the un-coupled core mode. However, it is presented that the asymmetric phenomenon can be overcome by scanning the UV laser beam along the fiber over the mask. The beam scanning method is able to suffer the same fluence of the UV laser beam on the fiber. Finally, a linearly chirped long-period fiber grating was made using the non-uniform UV laser beam. Due to the asymmetricity the chirping effect was not clearly observed. It is also presented that the beam scanning method could remove the asymmetric problem and recover the typical spectrum of the linearly chirped fiber grating.

In an ideal fiber grating having a uniform refractive index modulation, the reflection or the transmission spectrum is symmetric with equal amount of side lobes on both sides of the resonant wavelength of the fiber grating. It is observed that a long-period fiber grating made by a non-uniform UV laser beam through a uniform amplitude mask has an asymmetric transmission spectrum. The asymmetric characteristic is explained with Mach-Zehnder effect in the long-period fiber grating. The non-uniform UV laser beam makes also a non-uniform index modulation along the fiber core. Therefore, a beam coupled to a cladding mode at a section of the grating can be re-coupled to the core mode after passing a certain distance. The re-coupled beam makes Mach-Zehnder-like interference with the un-coupled core mode. However, it is presented that the asymmetric phenomenon can be overcome by scanning the UV laser beam along the fiber over the mask. The beam scanning method is able to suffer the same fluence of the UV laser beam on the fiber. Finally, a linearly chirped long-period fiber grating was made using the non-uniform UV laser beam. Due to the asymmetricity the chirping effect was not clearly observed. It is also presented that the beam scanning method could remove the asymmetric problem and recover the typical spectrum of the linearly chirped fiber grating.

A fully balanced (FB) transconductor using two multi-input single-ended (SE) CMOS transconductors is proposed, where the transconductors use MOS transitors operating in a triode region for achieving a wide linear input-range. SE circuits are easier to design than differential circuits and inherently reject common-mode (CM) signals. The multi-input structure is used to make a CM feedback loop and to determine an output CM voltage. A high-output-resistance current mirror is used in converting a differential signal to a single-ended signal in order to achieve a high common-mode rejection ratio (CMRR) and a high output-resistance of the transconductor. The FB transconductor achieves a 2-Vpp linear input range at a 2.5-V power supply and consumes 1.74 mA. The output resistance of the FB transconductor is 2 MΩ. It operates at 2 V with a linear input-range of 1.2 Vpp and at 1.6 V with a linear input-range of 0.9 Vpp. A 2.5-V 2.5-MHz FB Gm-C filter using the FB transconductors achieved a CMRR of 45 dB and a passband IIP3 of 32 dBm.