Loss-free complex impedance network elements

The concept of loss-free complex impedance network elements (i.e., elements with active and reactive impedance components and yet loss-free) is introduced. Synthesis of such elements by means of switched-mode power converters with appropriate control has been demonstrated to be possible. Some possible power processing-related applications of these elements are indicated, such as improved matching between ac sources and loads and VAR compensation. It has further been demonstrated that loss-free complex impedance elements are suitable for modeling many power processing systems for the purpose of analysis as well as for design purposes.     

Analysis and design of a continuous-wave terahertz photoconductive photomixer array source

An array of photoconductive photomixer/antenna elements as a continuous-wave terahertz source is proposed, and its radiation characteristic is studied. Employing photomixer/antenna elements in an array configuration increases available terahertz power, while each of the array elements consumes optical power less than its maximum sustainable power. A few microwatt terahertz power is achievable from a typical array structure. It is shown that the radiated beam can be steered by changing the angle between the two exciting laser beams.     

Simulation of wafer-scale GTO thyristors in circuits

A simulation technique that allows the study of large area power devices composed of many outwardly identical elements operating in a realistic power circuit has been developed. Results are presented showing the transient redistribution of current between a pair of GTO thyristor elements during turn-off under the influence of the power circuit. The method is validated by comparing simulated results with experimental measurements. Variations in carrier lifetime. diffusion uniformity, and gate contact position are studied, and they are shown to significantly alter the turn-off performance. Conclusions are drawn concerning the reliability of large area latching power devices with process inhomogeneity     

End-fire hybrid array antennas

A heuristic approach useful in the design of end-fire array antennas is described. When an array is scanned "beyond end fire," the last elements of the array, in the direction of the end-fire beam, generally receive net power transmitted by other elements of the array. This received power might conceivably be recirculated and reradiated at the price of substantial complexity in the feed network. It is relatively simple to absorb this power in appropriate resistive loads at the price of reduced gain. The resulting end-fire antenna is a hybrid-array consisting of two classes of elements: elements excited directly and elements excited parasitically. A compromise termination of these parasitic elements in reactive loads especially determined to preserve desired pattern characteristics is examined.     

Supply Switching With Ground Collapse: Simultaneous Control of Subthreshold and Gate Leakage Current in Nanometer-Scale CMOS Circuits

Power gating has been widely used to reduce subthreshold leakage. However, the efficiency of power gating degrades very fast with technology scaling, which we demonstrate by experiment. This is due to the gate leakage of circuits specific to power gating, such as storage elements and output interface circuits with a data-retention capability. A new scheme called supply switching with ground collapse is proposed to control both gate and subthreshold leakage in nanometer-scale CMOS circuits. Compared to power gating, the leakage is cut by a factor of 6.3 with 65-nm and 8.6 with 45-nm technology. Various issues in implementing the proposed scheme using standard-cell elements are addressed, from register transfer level to layout. These include the choice of standby supply voltage with circuits that support it, a power network architecture for designs based on standard-cell elements, a current switch design methodology, several circuit elements specific to the proposed scheme, and the design flow that encompasses all the components. The proposed design flow is demonstrated on a commercial design with 90-nm technology, and the leakage saving by a factor of 32 is observed with 3% and 6% of increase in area and wirelength, respectively.     

Quasi-Optical Power Combining of Solid-State Millimeter-Wave Sources

Very efficient power combining of solid-state millimeter-wave sources may be obtained through the application of quasi-optical resonators and monotfthic source arrays. Through the theory of reiterative wavebeams (beam modes) with application of the Lorentz reciprocity theorem, it is shown that planar source arrays containing 25 individual elements or more result in very efficient power transfer of energy from the source arrays to the fundamental wave-beam mode. It is further shown that for identical sources within a properly designed quasi-optical power combiner, the output power tends to increase much faster that number of source elements.     

Optimal Characteristics of an Arbitrary Receive Antenna

Several fundamental questions about the operation of receiving antennas are addressed, such as “Why does a receiving antenna scatter an incident field?” and “Under what conditions does a receive antenna capture all of the available incident power?” A new method is described by which the received power can be maximized for an arbitrary receiving antenna. The technique is first illustrated for two-dimensional infinite receiving arrays of electric and/or magnetic dipole elements, which result in simple plane waves for the scattered (re-radiated) fields. Optimal results (for maximum received power) are derived for several cases, and it is established that half the available incident power may be received by an array of electric (or magnetic) elements in free space, and that all available incident power may be received by an array that combines electric and magnetic elements, or one that incorporates a ground plane. Next, an arbitrary finite three-dimensional antenna enclosed by a mathematical spherical surface is treated using spherical vector wave functions. It is shown that half the available incident power can be received by such an antenna consisting of either TM or TE only elements, while all available incident power can be received when both TM and TE elements are used. It is also shown that the absorption efficiency for any optimal arbitrary antenna is 50%.      

Complementary ferroelectric-capacitor logic for low-power logic-in-memory VLSI

A novel nonvolatile logic style, called complementary ferroelectric-capacitor (CFC) logic, is proposed for low-power logic-in-memory VLSI, in which storage elements are distributed over the logic-circuit plane. Standby currents in distributed storage elements can be cut off by using ferroelectric-based nonvolatile storage elements, and the standby power dissipation can be greatly reduced. Since the nonvolatile storage and the switching functions are merged into ferroelectric capacitors by the capacitive coupling effect, reduction of active device counts can be achieved. The use of complementary stored data in coupled ferroelectric capacitors makes it possible to perform a switching operation with small degradation of the nonvolatile charge at a low supply voltage. The restore operation can be performed by only applying the small bias across the ferroelectric capacitor, which reduces the dynamic power dissipation. Applying the proposed circuitry in a fully parallel 32-bit content-addressable memory results in about 2/3 dynamic power reduction and 1/7700 static power reduction with chip size of 1/3, compared to a CMOS implementation using 0.6-/spl mu/m ferroelectric/CMOS.     

A conjugate gradient-based algorithm to minimize the sidelobe levelof planar arrays with element failures

Element failures increase the sidelobe power level of an array. Reconfiguring the amplitude and phase distribution of the remaining elements can partially compensate for the failed elements and thus reduce the sidelobe level. An algorithm is obtained that yields the reconfigured distribution by minimizing the ratio of the average peak sidelobe power level to the power in the main beam, taking into account the defective elements. The minimization of this nonlinear function is carried out via a conjugate gradient method. The algorithm is applied to the synthesis of sum and difference patterns of planar arrays     

Semicustom Design Methodology of Power Gated Circuits for Low Leakage Applications

The application of power gating to cell-based semi- custom design typically calls for customized cell libraries, which incurs substantial engineering efforts. In this brief, a semicustom design methodology for power gated circuits that allows unmodified conventional standard-cell elements is proposed. In particular, a new power network architecture is proposed for cell-based power gating circuits. The impact of body bias on current switch design and the layout method of current switch for flexible placement are investigated. The circuit elements that supplement cell-based power gating design are then discussed, including output interface circuits and state retention flip-flops. The proposed methodology is applied to ISCAS benchmark circuits and to a commercial Viterbi decoder with 0.18-mum CMOS technology.     

Power plane SPICE models and simulated performance for materialsand geometries

A SPICE model for power plane simulation has been developed. It is based on the geometries and materials of the power planes and uses a unit cell composed of RLC elements, transmission line elements or the HSPICE W-element. Simulated resonances in the frequency domain and delays in the time domain are consistent with results calculated from physical dimensions. SPICE model simulations compare well with hardware measurements in both the frequency and time domains. The role of dielectric thickness, dielectric constant and parallel pairs of power planes is demonstrated through simulation. The spreading inductance of power planes is defined, discussed and measured. Power plane performance in terms of impedance, resonances, damping and spreading inductance is optimized by the use of a thin dielectric layer between conductive planes     

垂直腔面发射激光器

The development and application of vertical-cavity surface-emitting lasers (VCSELs) are summarized in this paper. The emphasis is focused on the high power single and 2-D arrays bottom-emitting VCSELs with a wavelength of 980nm. A distinguished device performance is achieved. The maximum continuous-wave (CW) output power of large aperture single devices with active diameters up to 500μm is as high as 1.95W at room temperature, which is to our knowledge the highest value reported for a single device. Size dependence of the output power, the threshold current and the differential resistance are discussed. A 16 elements array with 200μm aperture size (250μm center spacing) of individual elements shows a CW output power of 1.32W at room temperature.     

Dual-band toroidal beam antenna for WLAN communications

A novel dual-band toroidal beam antenna for wireless local area network (WLAN) communications is presented. The antenna mainly consists of six dual-band inverted-L radiating elements and a twosection six-way microstrip power divider. By inserting slots into the radiating elements, two resonant frequencies are achieved at WLAN bands. By using the two-section six-way power divider, the six radiating elements are excited with equal amplitude and phase at the two working frequency bands. A prototype has been constructed and tested. Good toroidal beam radiation patterns for 2.4 and 5.2 GHz bands are obtained.     

A linear array of 980 nm VCSEL and its high temperature operation characteristics

A 980 nm bottom-emitting vertical-cavity surface-emitting laser linear array with high power density and a good beam property of Gaussian far-field distribution is reported. This array is composed of five linearly arranged elements with a 200 μm diameter one at the center, the other two 150 μm and 100 μm diameter ones at both sidesof the center with center to center spacing of 300/zm and 250 μm, respectively. A power of 880 mW at a current of 4 A and a corresponding power density of up to 1 kW/cm~2 is obtained. The temperature dependent characteristics of the linear array axe investigated. The thermal interaction between the individual elements of the VCSEL linear array is smaller due to its optimized element size and device spacing, which make it more suitable for high power applications. A peak power of over 20 W has been achieved in pulsed operation with a 60 ns pulse length and a repetition frequency of 1 kHz.     

A Universal Vector Controller for Four-Quadrant Three-Phase Power Converters

Power factor corrected (PFC) rectifiers, active power filters (APFs), static VAR compensators (STATCOM), and grid-connected inverters (GCI) are indispensable elements in distributed generation power systems. PFC rectifiers are essential for load side harmonic and reactive power correction, APFs can suppress the harmonics generated by nonlinear loads or sources, STATCOMs can control the power flow in the grid, while GCIs are the key elements bridging the renewable energy sources and the power grid. Previous theory and experiments have demonstrated that one-cycle control is capable of controlling all above mentioned three-phase converters, featuring excellent performance, simple circuitry, and low cost. This paper further unifies the control key equations for the previously mentioned converters, which results in a universal solution that realizes all these functions with a same controller. The concept has been verified by a 1-kVA prototype and supported by a series of experimental results     

A resonant-cap power combiner for two-terminal millimeter-wavedevices

A power combiner for three active two-terminal devices located under a common resonant cap is presented. An equivalent circuit with lumped elements describing the coupling between the devices is derived from a numerical finite-element simulation of the resonator. The applied monolithically integrated mounting technique for the active devices minimizes parasitic elements and gains high reproducibility and symmetry. Experimental results with GaAs IMPATT diodes on diamond heatsink of up to 500 mW at 91 GHz with a dc to RF conversion efficiency of 9.0% and excellent combining efficiency demonstrate the capability for power generation in the mm-wave region     

对A3型开关电源工作原理的一点讨论

日本三洋公司A3型彩色电视机开关电源,关于其工作原理的争论比较多,对电路的分析也不尽相同。本文通过对A3型开关电源电路原理的分析和通过实验所观测到的现象以及所测得的数据,详细阐述了电路中振荡部分和稳压部分的工作原理,对其中有争议的某些元器件的工作过程,以及它们在电路中的作用提出了自己的观点和看法。着重阐述了三极管V512工作在开关状态,以及它在稳压过程和开关管振荡时的作用。同时,对该电源中真正的定时元件C515、R526、R517等元件作了重点的测试和说明。     

Superdirective linear array antennas (optimization according to an integral criterion)

Phased array antennas with the element currents ensuring superdirectivity are analyzed. Three types of elements are studied: an isotropic dipole, a dipole oriented along the array axis (a collinear dipole), and a dipole oriented across the array axis (a perpendicular dipole). The currents on these elements are calculated using an integral criterion, according to which the total power radiated within some angular sector is minimized, whereas the power radiated in the main direction is kept at a prescribed level.     

Experiments on injection locking of active antenna elements foractive phased arrays and spatial power combiners

Two types of active antenna elements have been studied experimentally. One type uses a microstrip antenna with an active device mounted directly on the antenna. The other uses an active device coupled to a microstrip patch antenna through an aperture. Microstrip active antenna elements and two-element arrays have been demonstrated for both types of circuits. Injection locking of the antenna elements has been achieved through space and mutual coupling. The circuit Q factor was calculated based on the locking gain and the locking bandwidth. The power output from two elements has been successfully combined in free space with a combining efficiency of over 90%. For a single active antenna with a Gunn diode mounted directly on the patch, an electronic tuning range exceeding 9% has been achieved by varying the DC bias. The results should have many applications in low-cost active arrays, active transmitters, and spatial power combiners     

A 77-GHz Phased-Array Transceiver With On-Chip Antennas in Silicon: Transmitter and Local LO-Path Phase Shifting

Integration of mm-wave multiple-antenna systems on silicon-based processes enables complex, low-cost systems for high-frequency communication and sensing applications. In this paper, the transmitter and LO-path phase-shifting sections of the first fully integrated 77-GHz phased-array transceiver are presented. The SiGe transceiver utilizes a local LO-path phase-shifting architecture to achieve beam steering and includes four transmit and receive elements, along with the LO frequency generation and distribution circuitry. The local LO-path phase-shifting scheme enables a robust distribution network that scales well with increasing frequency and/or number of elements while providing high-resolution phase shifts. Each element of the heterodyne transmitter generates +12.5 dBm of output power at 77 GHz with a bandwidth of 2.5 GHz leading to a 4-element effective isotropic radiated power (EIRP) of 24.5 dBm. Each on-chip PA has a maximum saturated power of +17.5 dBm at 77 GHz. The phased-array performance is measured using an internal test option and achieves 12-dB peak-to-null ratio with two transmit and receive elements active