A flexible array synthesis method using quadratic programming

A highly flexible synthesis method for an arbitrary array is proposed to best approximate a desired array pattern in a minimum-mean-square-error sense. The basic idea of the technique is to form a quadratic program with its cost function given by the mean-square error between the array response and a properly selected pattern described by a known mathematical function. This quadratic program can be a constrained or unconstrained optimization problem depending on the requirements of the desired array pattern. In formulating the quadratic program, no assumption has been made on the gain/phase response or characteristics of the individual array elements. Therefore, one can synthesize an array of arbitrary shape to any appropriate pattern with the characteristic of the array elements taken into consideration as long as one is able to model the array accurately. The proposed method is used to synthesize arrays of different shapes, linear as well as planar arrays (including rectangular and circular planar arrays), using a Chebyshev polynomial or zero function as a design template, to illustrate the feasibility of the proposed method     

New two-inductor boost converter with auxiliary transformer

A new, two-inductor, two-switch boost converter topology and its variations suitable for applications with a large difference between the input and output voltage are described. The output voltage regulation of the proposed converters is achieved in a wide load and input-voltage range with constant-frequency control by employing an auxiliary transformer that couples the current paths of the two boost inductors.     

Transmission of block turbo coded digital audio over FM-SCA

In this paper, an efficient coded scheme for transmitting digital audio over the existing FM channel, by multiplexing it with the baseband FM signal, is described. Transmission of multiplexed signals in the FM baseband called FM-SCA (subsidiary communications authorization) has been previously used for low quality analog content and some low rate digital content. The investigated scheme opens up the possibility of achieving CD quality audio over FM-SCA by enabling high bitrate transmission using MPEG-I layer 3 and MPEG-AAC audio coding for the digital audio. These schemes provide CD quality audio at or below 128 kbps, MPEG-AAC being able to do so at rates as low as 96 kbps. Block turbo codes (BTC), which offer near Shannon's limit performance with relatively low hardware complexity requirements, provide the error protection. Block turbo codes have been shown to be particularly effective for high coding rates. The system uses OFDM in conjunction with 8PSK/16PSK to modulate the digital bitstream and fit it in the 44 kHz (54 to 98 kHz) band available in the FM baseband. Simulation results show an optimal system configuration for digital audio transmission in FM-SCA.     

Millimeter Wave MMIC Low Noise Amplifiers Using a 0.15 µm Commercial pHEMT Process

This paper presents millimeter wave monolithic microwave integrated circuit (MMIC) low noise amplifiers using a 0.15 µm commercial pHEMT process. After carefully investigating design considerations for millimeter-wave applications, with emphasis on the active device model and electomagnetic (EM) simulation, we designed two singleended low noise amplifiers, one for Q-band and one for V-band. The Q-band two stage amplifier showed an average noise figure of 2.2 dB with an 18.3 dB average gain at 44 GHz. The V-band two stage amplifier showed an average noise figure of 2.9 dB with a 14.7 dB average gain at 65 GHz. Our design technique and model demonstrates good agreement between measured and predicted results. Compared with the published data, this work also presents state-of-the-art performance in terms of the gain and noise figure.     

External Cavity Lasers Composed of Higher Order Gratings and SLDs Integrated on PLC Platform

Very compact 4‐channel 200‐GHz‐spacing external cavity lasers (ECLs) were fabricated by hybrid integration of reflection gratings and superluminescent laser diodes on a planar lightwave circuit chip. The fifth‐order gratings as reflection gratings were formed using a conventional contact‐mask photo‐lithography process to achieve low‐cost fabrication. The lasing wavelength of the fabricated ECLs matched the ITU grid with an accuracy of ×0.1 nm, and optical powers were more than 0.4 mW at the injection current of 80 mA for all channels. The ECLs showed single mode operations with more than 30 dB side lobe suppression.     

A Multi‐Strategic Concept‐Spotting Approach for Robust Understanding of Spoken Korean

We propose a multi‐strategic concept‐spotting approach for robust spoken language understanding of conversational Korean in a hostile recognition environment such as in‐car navigation and telebanking services. Our concept‐spotting method adopts a partial semantic understanding strategy within a given specific domain since the method tries to directly extract pre‐defined meaning representation slot values from spoken language inputs. In spite of partial understanding, we can efficiently acquire the necessary information to compose interesting applications because the meaning representation slots are properly designed for specific domain‐oriented understanding tasks. We also propose a multi‐strategic method based on this concept‐spotting approach such as a voting method. We present experiments conducted to verify the feasibility of these methods using a variety of spoken Korean data.     

A Wide Locking Range Differential Colpitts Injection Locked Frequency Divider

This letter proposes a new wideband Colpitts injection locked frequency divider (ILFD) and describes the operation principle of the ILFD. The circuit consists of a differential CMOS LC-tank oscillator and a direct injection topology. The divide-by-two ILFD can provide wide locking range, and the measurement results show that at the supply voltage of 2.4 V, the tuning range of the free running ILFD is from 4.46 to 5.6 GHz, about 1.14 GHz, and the locking range of the ILFD is from 8.03 to 11.63 GHz, about 3.6 GHz, at the injection signal power of 0 dBm. The ILFD dissipates 19.92 mW at a supply voltage of 2.4 V and was fabricated in 1P6M 0.18 mum CMOS process. At the tuning voltage of 1.2 V, the measured phase noise of the free running ILFD is -110.8 dBc/Hz at 1 MHz offset frequency from 4.94 GHz and the phase noise of the locked ILFD is -135.4 dBc/Hz, while the input signal power is -4 dBm.