三阶1-1-1级联Σ-Δ调制器的设计及仿真

采用MASH结构,设计了一款三阶(1-1-1)级联Σ-Δ调制器;讨论了各个模块的增益系数,设计了数字校正电路,并运用Matlab/Simulink对调制器进行了行为级仿真.当输入信号带宽为20 kHz,过采样比为64时,仿真模型得到87.7 dB的信噪比,精度为14.28位.与其他结构的调制器相比,该调制器更加稳定,动态范围更大,可应用于处理音频信号的A/D转换器.     

单级电流模式∑—△调制器的研究

文章对一阶和二阶单级电流模式∑-△调制器作了系统性能及稳定性分析,给出了两者的噪声传递函数。针对系统性能与稳定性这两个相对立的指标,给出了极点的指引。最后介绍了一个一阶调制器的设计实例。     

两通道声表面波全光纤声光调制器的研究

研制了一种新型的两通道声表面波(SAW)全光纤声光调制器,建立了多通道声波与光纤中光导波相互作用的耦合模方程并求出其解。SAW全光纤声光器件由两通道SAW器件和单模光纤构成。光纤嵌入SAW器件,光纤中的光导波被声表面波调制,由于两个通道中的SAW具有不同的中心频率,所以光纤中的光导波可以被具有不同频率的两个通道的SAW同时调制。测试了器件,实现了全光纤相干调制解调。     

On the Stability Analysis of High Order Sigma-Delta Modulators

In this paper we present an approach for stability analysis of high order Sigma-Delta modulators. The approach is based on a parallel decomposition of the modulator. In this representation, the general N-th order modulator is transformed into decomposition of low order modulators, which interact only through the quantizer function. In the simplest case of the loop filter transfer function with real distinct poles, the low order modulators are N first order ones. The decomposition considered helps to extract the sufficient conditions for stability of the N-th order modulator. They are determined by the stability conditions of each of the low order modulators but shifted with respect to the origin of the quantizer function, because of the influence of all other low order modulators. The approach is generalized for the case of repeated poles of the loop filter transfer function.     

Noise-shaping coding through bounding the frequency-weighted reconstruction error

A novel noise-shaping feedback coding scheme is derived by bounding and minimizing its filtered reconstruction error. The stability and performance of this coding scheme are rigorously analyzed. Analytic designs then can be obtained based on the derived stability conditions and noise-shaping equation. A fifth-order coder is designed for converting 3 MHz wide-band signal to a 4-bit quantized signal at a sampling rate of 96 MHz, with an effective resolution of 17 bits.     

Nonlinear theory of multimode action in loss modulated lasers

A set of cavity modes which are coupled together by an externally synchronous driven loss modulator is considered. The nonlinear polarization of the material is taken into account, and the mode coupling for the case when many modes are coupled together is treated nearly exactly. The formulas for the pulse shape and pulse width are explicitly derived for the case of a homogeneously broadened line. They show the dependence of these quantities on the system's parameters, such as pump power, modulator driving strength, detuning between modulator frequency, frequency spacing of the cavity modes, etc. Several configurations for the locked modes which have higher pulse widths are possible. This last result in particular seems to be completely new.     

A fourth-order bandwidth-reconfigurable delta-sigma modulator for audio applications

正A single loop fourth-order delta-sigma modulator is presented for audio applications.A reconfigurable mechanism is adopted for two bandwidth-based modes(8 kHz/16 kHz).Manufactured in the SMIC 0.13μm CMOS mixed signal process,the chip consumes low power(153.6μW) and occupies a core area of 0.98×0.46 mm~2.The presented modulator achieves an 89.3 dB SNR and 90.2 dB dynamic range in 16 kHz mode,as well as a 90.2 dB SNR and 86 dB dynamic range in 8 kHz mode.The designed modulator shows a very competitive figure of merit among state-of-the-art low voltage modulators.     

马赫曾德尔调制器偏压控制技术研究

介绍了马赫曾德尔调制器的工作原理及传输曲线随温度漂移引起偏置工作点改变的现象。理论推导出基于谐波分析的马赫曾德尔调制器偏压工作点稳定控制方法,同时通过导频信号来度量偏压工作点的漂移量。设计出基于FPAG的马赫曾德尔调制器偏压控制硬件模块,通过记录接入该模块前后PIN光电二极管电压及马赫曾德尔调制器输出光功率的变化情况,最终证实该偏压控制模块可以实现稳定马赫曾德尔调制器工作点的目的。     

GaAs／GaAlAs截止型光波导调制器的设计

利用近似解析方法，详细地讨论了金属覆盖层介质波导在截止点附近的模式传播特种和截止条件，并结合有效折射率方法讨论了脊高和脊宽对脊形波导截止条件的影响，设计了一种双层质结截止型强度调制器。     

自适应模糊滑模控制器设计

针对传统滑模控制的抖振问题,利用线性化反馈技术,将模糊自适应和滑模控制相结合,设计一种新型的模糊滑模控制器。通过模糊推理和基于Lyapunov函数的稳定性分析,获得模糊控制规则的自适应律,构成自适应模糊滑模控制器,有效解决了传统滑模控制中,需要确定参数摄动和外部干扰上确界不确定性问题,倒立摆上的运行结果表明该方法的有效性。     

Zero-input oscillation bounds in a bandpass ΣΔmodulator

Sufficient conditions for the state-variables of zero-input oscillations of a bandpass ΣΔ modulator structure to remain within a prescribed square region in the state-space are derived for the full range of parameter values of the digital resonator within the modulator     

Stability of multivariable control systems designed using reduced-order models: further results

Further new results regarding stability of the original model designed using reduced-order models are derived. The new stability conditions given are independent of how the reduced-order models are obtained, and the results could be adapted to any general multivariable frequency design methods.     

Averaging analysis approach for stability analysis of speed-sensorless induction motor drives with stator resistance estimation

In this paper, the stability property of speed-sensorless induction motor drives with stator resistance estimation is analyzed using the averaging analysis technique. Explicit stability conditions are then derived to clarify analytically when the instability may occur and how the regressor vectors used in the estimation and the integral adaptation gains should be designed to assure stability. The derived stability conditions also reveal that the coupling between the speed and the stator resistance estimation loops is the main cause of instability and that stabilization of each individual estimation loop is necessary but insufficient to guarantee stability. Instead of the conventional regressor vectors that are shown to make the estimation unstable in some regenerative regions, two new regressor vectors are introduced to achieve stability for the whole operating conditions. Moreover, investigation of the persistently exciting (PE) conditions points out theoretically the loss of identifiability of the rotor speed and the stator resistance at no loads and at zero frequency operations. Validity of all the analytical results is verified by simulation and experiment.     

A Four‐Channel Laser Array with Four 10 Gbps Monolithic EAMs Each Integrated with a DBR Laser

A distributed Bragg reflector (DBR) laser and a high speed electroabsorption modulator (EAM) are integrated on the basis of the selective area growth technique. The typical threshold current is 4 to 6 mA, and the side mode suppression ratio is over 40 dB with single mode operation at 1550 nm. The DBR laser exhibits 2.5 to 3.3 mW fiber output power at a laser gain current of 100 mA, and a modulator bias voltage of 0 V. The 3 dB bandwidth is 13 GHz. A 10 Gbps non‐return to zero operation with 12 dB extinction ratio is obtained. A four‐channel laser array with 100 GHz wavelength spacing was fabricated and its operation at the designed wavelength was confirmed.     

Variable centre frequency resonator based bandpass Σ-Δmodulator

A novel resonator-based bandpass Σ-Δ modulator with an in-built variable centre frequency feature is presented. This structure is designed by analytically determining and subsequently verifying through behavioural level simulations the necessary compensation hardware to be placed in the feedback to ensure stability and good dynamic range performance     

A low power reconfigurable multi-mode continuous time Delta Sigma modulator for seven different mobile standards with VCO-based quantizer

In this research a novel low power multi-mode continuous time Delta Sigma modulator was designed to be compatible with many mobile wireless standards. This modulator has a reconfigurable structure to adapt to various standards from 0.2 to 20 MHz. The designed modulator uses a VCO-based quantizer not only for lowering power consumption, but also for reducing the required chip area. The presented modulator can function with up to third order of noise shaping, or in a low power mode in which the loop filter is disabled and only the VCO-based quantizer is used. The proposed modulator was implemented and simulated in transistor level in 180 nm technology. This modulator can digitize at least seven standards (LTE (20 MHz)/WLAN/LTE (9 MHz)/WCDMA/UMTS/Bluetooth/GSM) with a favorable dynamic range (65–89 dB) and power consumption (9.1 mW–670 μW).     

Reciprocal Ferrite Devices in TEM Mode Transmission Lines

Several new reciprocal ferrite devices have been designed in TEM mode transmission lines to operate over both narrow and extremely broad bandwidths in the low-microwave frequency region. These include variable attenuators, an amplitude modulator, and a traveling-wave tube equalizer. Each component utilizes the attenuation associated with gyromagnetic resonance in low saturation magnetization ferrites. The techniques used to overcome the matching problems inherent in TEM mode transmission lines when ferrite loaded, and the design considerations pertinent to each component, are treated in detail. The parameters affecting the characteristics of each device are discussed and both final design and operating characteristics of the components are presented.     

A proposal for internal electrooptic intensity and frequency modulation of diode lasers

Modulation of a GaAs diode laser by a GaP electro-optic diode modulator internal to the laser cavity is proposed. Application of a reverse voltage to the modulator diode changes the state of polarization of the oscillating mode. One polarization component of the mode is efficiently coupled out of the cavity by reflection off a Brewster angle laser diode face. Solutions of the threshold equations for the mode frequencies, threshold gain, and the amplitude ratio and the relative phase of the polarization components of the oscillating mode exhibit novel behavior. This allows the laser-modulator combination to be used as either an intensity or a frequency modulated source. This frequency modulation regime in a coupling modulation configuration is an unexpected result and can be applied to other types of lasers. Calculations of the modulation characteristics based on measured properties of the GaP modulator diodes are presented. Operated as a Gürs-Müller coupling modulator (intensity modulation) the device could produce a depth of intensity modulation over 50 percent with a bandwidth of 1 to 3.5 GHz while dissipating only 0.1 watt in the modulator. Operated as a pure frequency modulator the device could have a 2.5 GHz bandwidth, again with 0.1 watt modulator dissipation. The modulator diode can also be used to produce pulse-code modulation. Up to one gigabit per second could be produced with the same modulator dissipation.     

K-Band Reciprocal Ferrite Phase Modulator (Correspondence)

A rectangular waveguide reciprocal phase modulator, making use of a longitudinal magnetic control field, was reported by Reggia and Spencer in 1957. This X-band phase modulator consisted of a longitudinally magnetized ferrite rod centrally located inside a rectangular wavegrride excited in its fundamental TE/sub 01/ mode. The outstanding advantages of this type modulator are the large phase shifts per unit length obtainable, simple geometric configuration, the high figure of merit possible, and the small magnetic control fields required. These modulators have since been designed for use at frequencies ranging from 3000 Mc to 70,000 Mc.     

利用环形调制器产生与解调过调幅信号

采用开关函数分析方法,利用二极管环形调制器电路产生与解调过调幅信号,导出实现的过调幅信号与解调输出信号表达式;由此,可将过调幅信号的产生与解调方法扩展到微波频段.