高线性2.4GHz LC压控振荡器设计

分析影响压控振荡器(VCO)的增益的因素,设计了一种提高VCO增益线性度的谐振回路结构,并运用此结构基于TSMC 0.18um RF CMOS工艺库设计了一个压控振荡器,调谐电压为0～1.5V,具有130MHz的调谐范围(2.35 GHz-2.48 GHz)。使用1.8 V电源,直流电流2.5 mA。利用ADS对该电路进行仿真,仿真结果显示,在2.4 GHz工作频率处,相位噪声约为-89.95 dBc/Hz@100 kHz。     

光泵磁力仪中压控振荡器的设计与实现

压控振荡器是光泵磁力仪的核心器件。为使光泵磁力仪能够对整个地磁场范围进行有效测量,需要一种输出频率范围宽。波段覆盖系数大,并具有较高瞬时稳定度的压控振荡器。采用多个变容二极管并联的方法,设计了基于西勒振荡电路形式,具有放大功能的压控振荡器。实验结果表明,该压控振荡器的输出频率范围大于8~20 MHz,波段覆盖系数达到2.5,输出波形幅度在整个频率范围内均达到3V以上,信号输出稳定,完全满足光泵磁力仪对地磁测量的要求。     

基于CMOS TSMC0．25μm工艺的2．4GHz频率合成器

为了能满足2.4 GHz频段蓝牙无线通信标准,采用互补型金属氧化物半导体(CMOS)TSMC0.25μm工艺,设计了一个全集成的2.4 GHz工作频率的频率合成器.重点分析和设计了锁相环(PPL)中核心器件压控振荡器(VCO)和频率分频器两个高频电路,其中,压控振荡器采用交叉耦合的LC振荡器结构以减少相位噪声和面积,频率分频器采用增强型的移相技术,以提高工作频率和稳定性.实验数据表明,压控振荡器的相位噪声以及系统的锁定时间皆可满足2.4 G频段的无线通信需求.     

S波段压控振荡器腔体结构设计

一、前言随着电子技术的不断发展,晶体管压控振荡器在电子设备中得到了广泛应用。尤其是高Q值、大变容比的二极管的发展,使晶体管压控振荡器更显示了其优越性。它与其它类型的压控振荡器相比较,具有电调谐速度快、调谐功率小,结构紧凑、重量轻、造价低等优点。因此在许多电子产品中得到应用。通过对几种结构类型的晶体管压控振荡器的比较,同轴腔体晶体管压控振荡器的优点更为明显。由于腔体的Q值高,容易达到频率稳定度高、噪声低、频谱纯的要求。     

VFC式绝对位移传感器研究

首次提出了一种“VFC式绝对位移传感器”,它采用电压—频率变换原理,利用分压电路的输出电压随电阻的变化而变化的特性,通过其对压控振荡器的输出控制,实现输出频率的同步变化,从而实现位移—频率的模数转换,通过对输出频率进行信号处理,实现对位移量的测量。这种传感器与分压电路的精度、压控振荡器的线性度有关,采用适当的分压电路时,可实现对直线位移和圆位移的测量。     

线性压控甚低频正弦振荡器的研制

本文提出一种新型的在甚低频段具有线性压控特性的正弦振荡器,其特点是由可集成化的压控模拟电感和外接电容组成回转器谐振回路。转换电容并调节压控电压可获得各种不同的十进制频率,频率可低至0.03Hz,甚致更低。文中讨论了模拟电感和由它构成的振荡器的电路原理和压控方程,并给出测试结果。     

SQUID磁强计的低噪声设计—频率合成及锁相技术的应用

本文阐述了在ＳＱＵＩＤ磁强计的电子线路中采用的频率合成及锁要上技术用来恢复淹没在噪声中的信号相位和频率，从而可以对信号进行相干检测的技术。本振信号及载波信号相同频率和采用高精度的稳压电源提高压控振荡器的信号的频谱纯度，使其信号有较纯净的输出，以最大限度地减少相位噪声。     

高性能的压控振荡调频电路设计与分析

设计了一种高性能的压控振荡调频电路,该电路载波质量高、频偏恒定、线性度高,受工艺影响小,消除了传统的锁相调频频偏受工艺和外界条件影响变化太大的缺陷。     

直接数字合成调频信号的研究

本文提出了直接数字合成调频信号的一种新方法，它采用两级相位累加器对波形存储器寻址的结构。在第一级寻址结构中产生的调制信号幅度序列和载波频率值在加法器中相加，并将相加的结果作为第二级相位累加器的频率控制字；再将第二级寻址结构中产生的调频信号序列通过数字－模拟转换器和低通滤波器，就实现了调频信号的直接数字合成。仿真结果表明本文提出的直接数字合成调频信号的方法是可行的。采用该方法合成调频信号具有硬件电路     

基于ispPAC20的压控振荡器及其应用

介绍了在系统可编程模拟器件ispPAC20的主要结构和性能特点，以及用一块ispPAC20实现的电压控制振荡器，并以该压控振荡器为基础构成了脉冲调制电路。     

Low Phase Noise VCO using Novel Harmonic Control Circuit Based on Quad-band Composite Right/Left-handed Transmission Line

In this paper,a novel Voltage-Controlled Oscillator(VCO)using the harmonic control circuit based on the quad-band Composite Right/Left-Handed(CRLH)Transmission Line(TL)is presented to reduce the phase noise without the reduction of the frequency tuning range and miniaturizing the circuit size.The phase noise has been reduced by the quad-band harmonic control circuit which has the short impedance for the second-and third-and fourth-and fifth-harmonic components.The CRLH TL with two Left-Handed(LH)(backward)and two Right-Handed(RH)(forward)pass bands are used to design the quad-band harmonic control circuit.The high-Q resonator has been used to reduce the phase noise,but it has the problem of the frequency tuning range reduction.However,the frequency tuning range of the proposed VCO has not reduced because the phase noise has reduced without the high-Q resonator.The miniaturization of the circuit size is achieved by using the quad-band CRLH TL instead of the conventional RH TL.The phase noise of VCO is-124.43～-122.67 dBc/Hz at 100 kHz in the tuning range of 5.729～5.934 GHz.     

两侧下拉电极MEMS压控电容的分析和优化

基于能量法对两侧下拉电极控制(SPEC)的MEMS(微机电系统)压控电容进行了分析和优化。使用数值迭代方法计算了压控电容可动极板的挠度试解函数,得到了试解函数形状在不同驱动电压下的曲线。计算结果与有限元仿真所得结果一致。在此基础上,给出了基于铝材料的两侧下拉电极MEMS压控电容的优化过程,得到了优化结果。对于初始应力5 MPa,杨式模量70 GPa,极板厚度1.5 μm,极板间距1 μm,总长度为600 μm的铝材料压控电容,控制电极采用70 μm的优化长度,可以实现变化比率为2∶1电容变化比率。结果表明采用(SPEC)结构的压控电容,能有效地减小或避免静电微机械结构特有的"崩塌"效应,获得较大的电容调节范围。     

A solid-mounted resonator-oscillator-based 4.596 GHz frequency synthesis

This paper describes a 4.596 GHz frequency synthesis based on a 2.1 GHz solid mounted resonator (SMR) voltage-controlled oscillator (VCO). The SMR oscillator presents a chip size lower than 2 mm(2), a power consumption of 18.2 mW, and exhibits a phase noise of -89 dBc/Hz and -131 dBc/Hz at 2 kHz and 100 kHz offset frequencies, respectively. The VCO temperature-frequency dependence is measured to be -14 ppm∕°C over a range of -20°C to 60°C. From this source, a low noise frequency synthesizer is developed to generate a 4.596 GHz signal (half of the Cs atom hyperfine transition frequency) with a phase noise of -81 dBc/Hz and -120 dBc/Hz at 2 kHz and 100 kHz from the carrier. The frequency synthesis output is used as a local oscillator in a Cs vapor microcell-based compact atomic clock. Preliminary results are reported and discussed. To the authors knowledge, this is the first development of a SMR-oscillator-based frequency synthesizer for miniature atomic clocks applications.     

A Novel Technique for Design of Ultra High Tunable Electrostatic Parallel Plate RF MEMS Variable Capacitor

This paper introduces a novel method for designing of low actuation voltage, high tuning ratio electrostatic parallel plate RF MEMS variable capacitors. It is feasible to achieve ultra-high tuning ratios way beyond 1.5:1 barrier, imposed by pull-in effect, by the proposed method. The proposed method is based on spring strengthening of the structure just before the unstable region. Spring strengthening could be realized by embedding some dimples on the spring arms with the precise height. These dimples shorten the spring length when achieved to the substrate. By the proposed method, as high tuning ratios as 7.5:1 is attainable by only considering four dimple sets. The required actuation voltage for this high tuning ratio is 14.33 V which is simply achievable on-chip by charge pump circuits. Brownian noise effect is also discussed and mechanical natural frequency of the structure is calculated.     

Frequency adaptive driver for ultrasonic vibrators with motional current feedback

A driving circuit of frequency adapting for an ultrasonic vibrator with motional current feedback has been presented in this paper. Via a voltage-controlled oscillator (VCO) and a digital/analog converter (DAC), the driving signal would be magnified by a linear power amplifier to actuate the vibrator. Since the vibrating velocities or displacements at the surface end of a vibrator could be predicted through the measurement of motional current, the motional current passing through the vibrator was detected by a current transformer (CT) type sensor as feedback to monitor the optimal level of output power. The calculation for phase difference and the tuning strategy for driving frequency were implemented by a microcontroller integrated with an A/D converter and a voltage comparator as well as the signal attenuation and level tuning circuit. The experiment demonstrates that the temperature effect corresponding to frequencies is at 9.75 Hz/°C shifting and the external loading reflected to frequencies is about 8.3 Hz/gm offset. The proposed circuit has the great performance in rejecting the disturbances from external loading and thermal effect.     

Note: Piezoelectric strain voltage sensing at ultra-low frequencies

Piezoelectric sensors have emerged as a versatile tool for measurement of various quantities such as pressure, acceleration, strain, or force across many industrial applications. When mechanically strained, electric charges are produced inside a piezoelectric transducer. These charges result in an electric field that may be measured as a voltage difference between two electrodes, from which the strain can be inferred. To measure this voltage the sensor must be interfaced with an external device that would typically have a finite input impedance. This, together with the capacitive nature of the piezoelectric sensor, results in an inability to measure strain at low frequencies. We propose a method, based on using a varactor diode in an oscillator circuit, which can result in accurate measurements of the piezoelectric voltage at ultra-low frequencies. We demonstrate successful measurements at 1 mHz.     

On the selection of tuning methodology of FOPID controllers for the control of higher order processes

In this paper, a comparative study is done on the time and frequency domain tuning strategies for fractional order (FO) PID controllers to handle higher order processes. A new fractional order template for reduced parameter modelling of stable minimum/non-minimum phase higher order processes is introduced and its advantage in frequency domain tuning of FOPID controllers is also presented. The time domain optimal tuning of FOPID controllers have also been carried out to handle these higher order processes by performing optimization with various integral performance indices. The paper highlights on the practical control system implementation issues like flexibility of online autotuning, reduced control signal and actuator size, capability of measurement noise filtration, load disturbance suppression, robustness against parameter uncertainties etc. in light of the above tuning methodologies.     

Low-noise high-performance current controllers for quantum cascade lasers

Quantum cascade lasers have ushered in a new era of enhanced capability for chemical sensing. The higher current and voltage demands of these devices over their laser diode counterparts have also ushered in the demand for more capable drive electronics. The current-sensitivity and high frequency response of these devices have continued the desire for low noise, stability, and agility enjoyed by the laser diode community for many years. This article addresses the issue of maintaining these characteristics at the currents and voltages required, and presents example performance of current controllers developed by the author at Pacific Northwest National Laboratory, achieving output currents up to 2 A and compliance voltages of 15 V, with noise levels close to the Johnson noise of the internal resistors, typically a few nA/√Hz. Rapid full-depth current modulation up to 100 kHz is also demonstrated.     

恒温型热线风速测量系统动态特性分析及试验验证

为测量不同工况下流场的脉动流速,恒温型热线风速测量系统在满足稳定性要求的同时,必须具备宽频带的动态特性。分别对热线探头工作过热比、放大器增益、惠斯通桥臂电阻、流场稳定流速、补偿电感和偏置电压等参量对热线测量系统动态特性的影响效果进行了仿真分析,结果表明:增大热线探头工作过热比、放大器增益和流场稳定流速及减小桥臂电阻均能提高系统的频响;补偿电感与热线探头连接电缆电感及电路寄生电感匹配时,系统频响最佳;在上述参量配置不当时,系统频响降低,系统振荡加剧甚至不能正常工作,而提高偏置电压能消除振荡并使系统恢复稳定,同时获得平稳的动态频响。因此,提出了基于偏置电压的动态特性调节方法。方波试验结果表明,基于偏置电压的频响调节方法能使系统在不同的脉动流速测量中均能获得较为平坦的频响,且调节过程简便。     

基于虚拟仪器技术的APD噪声等效功率测量系统

利用锁相放大器测量雪崩光电二极管(APD)特定工作频率下的噪声电压,使用示波器测量APD在调制光输入条件下的电压值,使用功率计测量输入调制光能量值,以此测出APD的噪声等效功率(NEP).并在测量过程中利用截尾平均数、变异系数等统计方法消除噪声干扰.同时,利用LabVIEW图形设计软件制作了一整套自动测试程序.实际操作...