Fast amplitude control of a harmonic oscillator

The response time of an amplitude-controlled harmonic oscillator has been greatly reduced by the use of sampling techniques in the control loop.     

A Wien bridge RC oscillator with fast amplitude control

The paper describes fast amplitude control in a Wien bridge RC oscillator. This fast control is achieved restoring ( within each period) a node voltage in the passive RC two-port of positive feedback. As a result the new value of the output voltage amplitude can be established with the delay which is not more than one oscillation period. The total harmonic distortion ( THD) is calculated and the condition of low distortion is established. The low-THD oscillator includes the circuit for damping-ratio control as well. The experimental data show that THD below 0-1% is achieved.     

Fast amplitude control in twin-T bridge RC oscillators

When a sinusoidal voltage is applied to the symmetrical twin-T bridge, the voltages at the inner nodes of the bridge have equal amplitudes and are shifted by 90°. If they are squared and summed, the resulting DC voltage can be used to control the gate of a field-effect transistor connected to the bridge. The oscillator with such a control system simultaneously has low distortion and fast amplitude transient response.     

Simple RC chaotic oscillator

An RC oscillator exhibiting chaotic behaviour is described. It contains two opamps, a Wien bridge and a diode used as a nonlinear device. The typical waveforms, the phase portraits, the power spectra and the correlation dimension of the attractor are presented to illustrate the chaotic oscillations     

Insensitive very-low-frequency RC oscillator

The frequency-sensitivity problem associated with some types of very-low-frequency oscillators is examined and an insensitive structure is presented.     

A temperature-stable RC transistor oscillator

Generation of stable sinusoidal oscillations of fairly good waveform has been realized in a basic multivibrator circuit by optimizing load and coupling elements and introducing an amplitude defining mechanism with the use of emitter coupling. The resulting differential operation introduces an inherent tendency of self-compensation against changes of active circuit parameters, and the frequency remains practically independent of temperature change even though transistors are used.     

稳定振幅的LC振荡器

很多应用中都要用到宽范围可调的LC振荡器,它能够在电路输出负载变化时提供近似恒定的频率,几乎无谐波的输出。从设计观点看,省去感性或容性LC电路抽头以及省掉与频率确定电路中的变压器耦合可以简化制造与生产过程,就像将调谐LC电路一侧接地一样。这些需     

一种新型高精度RC振荡器电路设计

在对传统的振荡器电路的分析比较基础上,基于振荡器的基本工作原理,结合误差比较器技术,提出了一种新型高性能低功耗的RC振荡器.利用CSMC的DPDM Bsim3模型和Cadence的Spectre仿真器对该电路进行了模拟和仿真,结果表明该电路与传统的振荡器相比具有精度高、功耗低的优点.最后对该电路进行版图设计,版图面积为70.5×62.59μm2.     

New type of variable-frequency RC oscillator

A technique of realising a variable-frequency RC oscillator is proposed. The frequency of oscillation is found to be the difference of two RC functions, which permits a very-low-frequency realisation. The frequency variation is obtained by controlling a single resistance in the network.     

Nullor representation of variable-frequency RC oscillator

A recently proposed RC oscillator is represented in nullor form. By rearranging the nullors, it is shown that only one operational amplifier is required, instead of two. Means are proposed to overcome a bias problem inherent in the original design.     

一种带振幅调节的晶体振荡器

设计了一种带振幅控制的晶体振荡器,用于32 768 Hz的实时时钟.振幅调节环采用源接地振荡器形式来得到高的频率稳定性和低的功耗.使用MOS管电阻有效的减小了版图面积.电路在0.35 μm、5 V CMOS工艺上实现,仿真和测试结果都能满足设计要求.     

RC op-amp implementation of hysteresis chaotic oscillator

An RC op-amp implementation of an oscillator based on hysteretic nonlinearity is proposed. Experimental results are reported, showing its main dynamic behaviours     

Large amplitude operation of the nonlinear oscillator

A two-parameter oscillator equation is obtained from the inverse tangent approximation to the amplifier function. The equation accounts for the exponential wave shape of relaxation oscillations, which cannot be explained by van der Pol's equation.     

RC正弦波振荡电路教学设计

本文以8音阶简易电子琴电路引入,从信号产生和8音阶实现两个问题入手,引出RC正弦波振荡电路理论,并拓展应用到实现简易电子琴的设计.通过全员参与,步步设疑,层层探究,理论与应用结合,激发了学员兴趣,提高了学员能力.     

Frequency stabilization of power-combining grid oscillator arrays

In this paper, we report the results of phase locking of grid oscillator arrays. First, a voltage-controlled grid oscillator array with a center frequency of 4.7 GHz and with a 300-MHz electric tuning range was locked to a frequency synthesizer through a phase-locked loop. Second, a 4 × 4 and a 6 × 6 grid oscillator arrays were locked by way of the injection locking. In both methods, a simple loop antenna mounted on the reflection mirror was used for taking/injecting signals from/to the array. Results show that the phase noise performance is improved significantly in the locked oscillator arrays     

Wide-band amplitude control of the second-order oscillator circuit

In this paper, a new analysis technique of an ordinary second-order oscillator which is based on multi-time concept is proposed. This mathematical analysis results in a new closed-form solution of a system complete response. It is found that amplitude of the natural response is not constant but varied with the forced response of the system. For a constant forcing function proposed, the new analysis is identical to the conventional analysis. In the case of time-varying forcing function, however, it is different from the conventional approach. Based on such analysis, it implies that the amplitude of a second-order oscillator can easily be controlled by forced response of the system. Hence, the obtained result based on the proposed analysis technique provides a proper mathematical solution for the system, especially in a time-varying forcing function. Moreover, the mathematical analysis for the wide-band characteristic of a second-order oscillator is also described. The experimental results demonstrate the responses of the oscillator which agree well between the theoretical and simulation results.     

Analytical equations for oscillation amplitude of MOS Colpitts oscillator

New analytical equations are presented for amplitude analysis of metal–oxide–semiconductor (MOS) Colpitts oscillator. These equations are obtained from a large signal analysis that includes MOS operation in the saturation, triode and cutoff regions. The analysis is based on a reasonable estimation for the output voltage waveform. The estimated waveform must satisfy the nonlinear differential equations governing the circuit. The validity of the proposed method and the resulting equations has been verified through simulations using TSMC 0.18?µm complementary MOS process. The results are also compared with the other methods. Simulation results show high validity of the proposed equations.