On Development of a Rotary–Linear Actuator Using Piezoelectric Translators

Piezoelectric actuators have become standard elements in microsystem technology. A piezoelectric translater conventionally works as a pure linear actuator (piezotranslator) due to its inherent working principle. If a rotation is implemented with the basic piezoelectric actuation elements, a transmission mechanism is required. This paper presents the development and construction of a novel integrated piezoelectric rotary-linear actuator system that provides two degrees-of-freedom (DoF), including design concept and dynamic modeling. A prototype actuator system has been built to conduct experiments, and the experimental results are in agreement with the simulation results obtained using the derived dynamic model of the system.     

A Novel Single-Stage Series-Resonant Buck–Boost Inverter

A novel single-stage series-resonant buck–boost inverter (SRBBI) is proposed in this paper. The main attribute of the novel inverter topology is the fact that it generates an ac output voltage larger or lower than the dc input one, depending on the instantaneous duty cycle. This property is not found in the classical voltage-source inverter, which produces an ac output instantaneous voltage which always lower than the dc input voltage. The state-space averaging approach is used to estimate and examine the steady-state and dynamic character of the new single-stage SRBBI. The principle of operation, theoretical analysis, and experimental results of the proposed inverter, rated 500 W and operating at 40 kHz, are provided in this paper to verify the performance of the SRBBI.     

New Architectures for Radio-Frequency DC–DC Power Conversion

This document proposes two new architectures for switched-mode dc–dc power conversion. The proposed architectures enable dramatic increases in switching frequency to be realized while preserving features critical in practice, including regulation of the output across a wide load range and high light-load efficiency. This is achieved in part by how the energy conversion and regulation functions are partitioned. The structure and control approach of the new architectures are described, along with representative implementation methods. The design and experimental evaluation of prototype systems with cells operating at 100MHz are also described. It is anticipated that the proposed approaches and ones like them will allow substantial improvements in the size of switching power converters and, in some cases, will permit their integrated fabrication.     

A Current Re-Use Mixer and a Push–Pull Buffer for Base Station Applications

A high dynamic range (DR) current reuse mixer and a linear push–pull buffer with an active area of 0.11mm$times$0.1mm were realized for base station applications in a 5-V complementary 0.4-$muhboxm$SiGe process. At 2GHz, a mixer test block with the proposed mixer achieves a nominal measured DR of$+$154 dB, while drawing 29 mA from a 3.3-V supply, whereas the push–pull buffer outputs an$ OP_1 dB$of$+$9dBm, while drawing 33 mA from a 5-V supply.     

The electronic theory of tape–helix traveling–wave structures

An electronic theory of the operation of tape-helix traveling-wave structures is given. This includes the case of traveling-wave amplifiers and backward-wave oscillators operating on any space harmonic. The method of solution is based upon an integral equation for the longitudinal electric field which is solved approximately for the case of small beam currents. This method is equally applicable to thin beams, thick beams, and annular beams with or without a transverse variation of dc density or velocity. Explicit expressions are obtained for the impedance and space-charge parameter of each space harmonic.     

高精度测量雷达动态精度分析方法研究

高精度测量雷达动态精度是靶场测控系统的重要指标之一。文中针对靶场测控设备精度问题,结合精度校飞试验,采用动态测量精度鉴定方法,进行了原理分析,并通过数据精度验证,得出了高精度测量雷达动态精度分析可行性结论,并指出了方法中的一些研究方向与使用中应注意的问题。     

Low–frequency circuit theory of the double–base diode

The double-base diode is a single-junction semiconductor triode. When an electric potential is applied between the two ohmic contacts, a negative-resistance is obtained between the junction and one of the ohmic contacts. This negative resistance is bounded by two positive-resistance regions, one of considerably high magnitude which corresponds to the cut-off state and one of very low magnitude which corresponds to a saturating condition. The magnitude of the negative resistance is related to the ratio of majority-to-minority carrier mobilities. Small-signal low-frequency equivalent circuits are developed to approximate the double-base diode in each of the operating regions of the negative-resistance characteristic and equations for current and voltage amplification, input and output resistance and power gain are developed. The important circuit parameters are related to the physical constants of the device.     

Small–signal analysis of floating–junction transistor switch circuits

In this paper some characteristics of switch circuits using junction transistors are analyzed. The switch properties result from the large changes in small-signal admittance of one junction of a transistor when the bias polarity of the other junction is reversed. The characteristics analyzed include the small-signal, low-frequency conductance and the associated potentials. The circuits are suitable for low level modulators and commutators.     

A 12–18-GHz Three-Pole RF MEMS Tunable Filter

This paper presents a state-of-the-art RF microelectromechanical systems (MEMS) wide-band tunable filter designed for the 12–18-GHz frequency range. The coplanar-waveguide filter, fabricated on a glass substrate using loaded resonators with RF MEMS capacitive switches, results in a tuning range of 40% with very fine resolution, and return loss better than 10 dB for the whole tuning range. The relative bandwidth of the filter is$hbox5.7pm hbox0.4hbox%$over the tuning range and the size of the filter is 8 mm$, times ,4$mm. The insertion loss is 5.5 and 8.2 dB at 17.8 and 12.2 GHz, respectively, for a 2-$hboxkOmega/hboxsq$bias line. The loss improves to 4.5 and 6.8 dB at 17.8 and 12.2 GHz, respectively, if the bias line resistance is increased to 20$hboxkOmega/hboxsq$. The measured$ IIP_3$level is$≫$37 dBm for$Delta f ≫ 200$kHz. To our knowledge, this is the widest band planar tunable filter to date.     

The MIMO ARQ Channel: Diversity–Multiplexing–Delay Tradeoff

In this paper, the fundamental performance tradeoff of the delay-limited multiple-input multiple-output (MIMO) automatic retransmission request (ARQ) channel is explored. In particular, we extend the diversity-multiplexing tradeoff investigated by Zheng and Tse in standard delay-limited MIMO channels with coherent detection to the ARQ scenario. We establish the three-dimensional tradeoff between reliability (i.e., diversity), throughput (i.e., multiplexing gain), and delay (i.e., maximum number of retransmissions). This tradeoff quantifies the ARQ diversity gain obtained by leveraging the retransmission delay to enhance the reliability for a given multiplexing gain. Interestingly, ARQ diversity appears even in long-term static channels where all the retransmissions take place in the same channel state. Furthermore, by relaxing the input power constraint allowing variable power levels in different retransmissions, we show that power control can be used to dramatically increase the diversity advantage. Our analysis reveals some important insights on the benefits of ARQ in slow-fading MIMO channels. In particular, we show that 1) allowing for a sufficiently large retransmission delay results in an almost flat diversity-multiplexing tradeoff, and hence, renders operating at high multiplexing gain more advantageous; 2) MIMO ARQ channels quickly approach the ergodic limit when power control is employed. Finally, we complement our information-theoretic analysis with an incremental redundancy lattice space-time (IR-LAST) coding scheme which is shown, through a random coding argument, to achieve the optimal tradeoff(s). An integral component of the optimal IR-LAST coding scheme is a list decoder, based on the minimum mean-square error (MMSE) lattice decoding principle, for joint error detection and correction. Throughout the paper, our theoretical claims are validated by numerical results     

An analysis of focusing and deflection in the post–deflection–focus color kinescope

In the Post-Deflection-Focus Color Kinescope, there is an array of parallel wires next to the phosphor screen for the purpose of focusing the electron beam and for deflecting it up and down in order to change colors. Expressions are derived for the deflection sensitivity and focusing properties of such a system which are applicable for all points within the picture area. The theoretical results are compared with experimental measurements; good agreement is obtained. Contour maps showing the variation over the grid plane of deflection sensitivity and the voltage ratio for optimum focus are included.     

Zero-Voltage and Zero-Current Switching Full-Bridge DC–DC Converter With Auxiliary Transformer

A novel zero-voltage and zero-current switching (ZVZCS) full-bridge phase-shifted pulsewidth modulation (PWM) converter using insulated gate bipolar transistors (IGBTs) with auxiliary transformer is proposed to improve the properties of the previously presented converters. ZVZCS for all power switches is achieved for full load range from no-load to short circuit by adding active energy recovery snubber and auxiliary circuits. The principle of operation is explained and analyzed and experimental results are presented. The features and design considerations of the converter are verified on a 3-kW, 50-kHz IGBT based experimental circuit.     

Explicit Space–Time Codes Achieving the Diversity–Multiplexing Gain Tradeoff

A recent result of Zheng and Tse states that over a quasi-static channel, there exists a fundamental tradeoff, referred to as the diversity-multiplexing gain (D-MG) tradeoff, between the spatial multiplexing gain and the diversity gain that can be simultaneously achieved by a space-time (ST) code. This tradeoff is precisely known in the case of independent and identically distributed (i.i.d.) Rayleigh fading, for Tgesn_t+n_r-1 where T is the number of time slots over which coding takes place and n_t,n_r are the number of transmit and receive antennas, respectively. For Tt+n_r-1, only upper and lower bounds on the D-MG tradeoff are available. In this paper, we present a complete solution to the problem of explicitly constructing D-MG optimal ST codes, i.e., codes that achieve the D-MG tradeoff for any number of receive antennas. We do this by showing that for the square minimum-delay case when T=n_t=n, cyclic-division-algebra (CDA)-based ST codes having the nonvanishing determinant property are D-MG optimal. While constructions of such codes were previously known for restricted values of n, we provide here a construction for such codes that is valid for all n. For the rectangular, T>n_t case, we present two general techniques for building D-MG-optimal rectangular ST codes from their square counterparts. A byproduct of our results establishes that the D-MG tradeoff for all Tgesn_t is the same as that previously known to hold for Tgesn_t+n _r-1     

A 200-MHz IF 11-bit fourth-order bandpass ΔΣ ADC inSiGe

This paper demonstrates the design of an integrated fourth-order bandpass sigma-delta converter, which is capable of digitizing a 200-kHz band at 200 MHz with 11-bit accuracy. The converter has been successfully fabricated in a 50-GHz SiGe bipolar technology, and the modulator consumes 21 mA at 3 V. The converter is aimed at the digitization of wireless signals at a high first intermediate frequency with a wide dynamic range     

An analysis of a super wide–band FM line discriminator

This paper presents a dynamic analysis of an extremely wide-band FM line discriminator consisting of a pair of transmission lines and coupling resistors. The relationship between the harmonic distortion of the output waveform of the discriminator and the permissible frequency deviation of the input signal is analyzed in detail by the method of Fourier transform. It is shown that the coupling resistor constant γ (see Fig. 1) should be set at unity from the viewpoint of the sensitivity of the discriminator and the constant input impedance of the discriminator over the frequency deviation of the input signal. Theoretically, an FM signal having 100 per cent frequency deviation could be detected by this discriminator with 2.67 per cent harmonic distortion while the input impedance of the discriminator remains constant (equal to characteristic impedance of the transmission line Z0) during the frequency deviation. Experimental results are presented to verify the theoretical results obtained. The characteristic curve of the discriminator is linear for 40 per cent frequency deviation from the carrier frequency 85.5 Mc, and its input impedance remains within ±14 per cent of the idea value Z0.     

Space–Time Precoding for Mean and Covariance Feedback: Application to Wideband OFDM

Space–Time Precoding for Mean and Covariance Feedback: Application to Wideband OFDM We consider optimization of the capacity of a multi-input single-output wideband cellular “downlink,” in which the base station has estimates of the statistics of the spatial channel. Our main focus is on orthogonal frequency-division multiplexed systems, although some of our results apply to single-carrier systems as well. Prior work has shown that estimates of the channel spatial covariance can be obtained without overhead for both frequency-division duplex (FDD) and time-division duplex (TDD) systems by suitably averaging uplink measurements. In this paper, we investigate the benefits of supplementing this “free” covariance feedback with mean feedback, where the latter refers to estimates of the spatial channel realization in each subcarrier. Mean feedback can be obtained using reciprocity for TDD systems, and requires explicit feedback for FDD systems. We first devise strategies for using both covariance and mean feedback, mainly restricting attention to beamforming, which is optimal or near-optimal for many outdoor channels with narrow spatial spread. Second, since mean feedback degrades rapidly with feedback delay for mobile channels, we develop quantitative rules of thumb regarding the accuracy required for the mean feedback to be a useful supplement to the already available, and robust, covariance feedback. Our results validate the following intuition: the accuracy requirements for mean feedback to be useful are more relaxed for channels with larger spatial spread, or for a larger number of transmit elements.     

Coding for the Feedback Gel'fand–Pinsker Channel and the Feedforward Wyner–Ziv Source

We consider both channel coding and source coding, with perfect past feedback/feedforward, in the presence of side information. It is first observed that feedback does not increase the capacity of the Gel'fand-Pinsker channel, nor does feedforward improve the achievable rate-distortion performance in the Wyner-Ziv problem. We then focus on the Gaussian case showing that, as in the absence of side information, feedback/feedforward allows to efficiently attain the respective performance limits. In particular, we derive schemes via variations on that of Schalkwijk and Kailath. These variants, which are as simple as their origin and require no binning, are shown to achieve, respectively, the capacity of Costa's channel, and the Wyner-Ziv rate distortion function. Finally, we consider the finite-alphabet setting and derive schemes for both the channel and the source coding problems that attain the fundamental limits, using variations on schemes of Ahlswede and Ooi and Wornell, and of Martinian and Wornell, respectively     

Validating the SAR Wavenumber Shift Principle With the ERS–Envisat PS Coherent Combination

Continuity of the European Remote Sensing Satellite Synthetic Aperture Radar (ERS SAR) archive by means of Envisat Advanced SAR (ASAR) data acquired from March 2002 has introduced the problem of the coherent combination of images coming from sensors with slightly different frequencies. The spectral shift principle states that in case of extended distributed targets, the frequency shift is equivalent to a change of looking angle. In this paper, the same principle is exploited to analyze the behavior of permanent scatterers (PSs) with an extension that is smaller than the ground resolution cell. The conditions under which the PSs identified by ERS can be continued by Envisat are then theoretically determined and experimentally validated. Moreover, this analysis shows that acquisitions characterized by different frequencies can be used to identify the slant-range position of scatterers with high subcell accuracy (tens of centimeters). From the processing side, a very precise images coregistration step is required to get the results described in this paper.     

Bending loss evaluation of single-mode fibres with arbitrary coreindex profile by far-field pattern

An evaluation of the bending loss of single-mode fibers based on the measured mode field is described. The field decay constant and the normalized field intensity in the cladding are determined. Experimental results verified the validity of this method. Its accuracy is determined by the accuracy of field measurement. The mode field is calculated from the far-field distribution measured with finite dynamic range of more than 50 dB. Far-field measurement with finite dynamic range limits the accuracy of field evaluation. Dispersion shifted fibers are easier for evaluation because of the wider far-field distribution. Bending loss and mode field diameter can be measured simultaneously, and the method is applicable to any single-mode fibers with a matched clad structure. A microbending loss formula is also determined by the decay constant and the normalized field intensity in the cladding as well as uniform bending loss