浅析正弦振荡器的原理和制作

本文介绍了电子技术领域中广泛应用的正弦波振荡器。主要介绍LC选频网络、振荡原理以及LC振荡器、RC振荡器和晶体振荡器的一般性原理以及制作需注意的问题。     

一种低噪声C类LC压控振荡器的设计

为了改善压控振荡器相位噪声,基于40 nm CMOS工艺,设计一种低噪声C类LC压控振荡器。交叉耦合NMOS对管通过电流镜偏置作为电路的电流源,并采用共模反馈偏置电路使交叉耦合PMOS对管工作在饱和区,保证LC压控振荡器实现C类振荡。通过差分可变电容的设计,压控振荡器的增益减小,压控振荡器的相位噪声得到改善。设计了4组开关电容进行调节,增大压控振荡器的调谐范围。仿真结果表明,处于1.2 V的电压下,压控振荡器振荡频率范围在4.14～5.7 GHz,频率调谐范围变化率达到31.2%,相位噪声为-112.8 dBc/Hz。     

基于OrCAD/PSpice的波形发生电路设计仿真

对正弦波振荡器工作原理及振荡电路的起振条件进行了分析与研究。根据LC三点式振荡电路的组成原则设计并改进了电容三点式振荡器电路,在O rCAD/PSp ice仿真软件中对电路进行了时域及频域仿真分析,给出了振荡波形,测量了振荡频率。仿真结果表明通过对电路的改进改善了波形,所设计电路波形与理论值相接近。     

压控振荡器在射频通信电路中的应用

随着现代通信系统和现代雷达系统的出现,射频电路需要在特定的载波频率点上建立稳定的谐波振荡,以便为调制和混额创造必要的条件.设计了一个振荡频率在1.14～1.18 GHz的负阻LC压控振荡器,实现了压控振荡器的宽调频,使频率范围达到加MHz.并且为避免在外部电路对压控振荡器(VCO)的影响,在电路中加入射极跟随器作为buffer,起到阻抗变换和级间隔离的作用.为负阻LC压控振荡器的设计提供了一种参考电路.     

LC振荡器相位噪声的非线性摄动分析技术

相位噪声是振荡器的重要性能指标,通过对振荡器的非线性微分方程的推导,从而引入新的参数来考虑振幅噪声和相位噪声之间的相关性同时把这些参数和振荡器的工作点联系起来。并且这些公式推导也考虑了LC谐振回路中振幅噪声和相位噪声之间的相关性。在此基础上这里研究了如何在时域状态方程下将噪声看成是对振荡输出信号的小扰动,并建立引入噪声后的随机微分方程,实现LC振荡器的相位噪声分析技术。     

晶体管电路讲座(四)

四、晶体管正弦振荡器利用结型晶体管可产生低频和高频的正弦振荡,它们在形式上与电子管自激振荡器有许多相似之处,如在电子管电路中有调板式、哈特莱式、考毕兹式等LC振荡器,在晶体管中也可有对应的形式,但在具体讨论时,晶体管电路有其特殊要求.在此,只简单分析晶体管振荡器的起振条件及振荡频率,故可用线性方法进行分析,而把晶体管看成是线性有源的器件.     

幅度高度稳定的振荡器

在一些精密仪器和仪表中,需要幅度高度稳定的振荡器,一般的RC振荡器或LC振荡器,幅度稳定度只有几十分之一.在通常的振荡器中,晶体管起着双重作用,第一为系统的负阻作用,使系统产生和维持振荡;第二为限幅作用,使振荡幅度保持一定程度的稳定性.众所周知,当振荡器的幅度不断增大渐渐进入饱和     

锁相环电路中压控振荡器的分析与设计

本文设计了一个应用于高频锁相环（PLL）系统的负阻LC压控振荡器,在传统LC压控振荡器基础上,通过采用二次谐波滤波技术降低了振荡器的相位噪声,并完成了电路的仿真。仿真结果表明,该压控振荡器的振荡频率在1．9—2．1GHz,其频率调节范围达到200MHz,并且在距中心频率1MHz处其相位噪声为-148．825dBc／Hz...     

LC振荡器输出幅度的分析和计算

LC振荡器工作在稳态振荡时,运用到晶体管非线性区域,其输出幅度不能简单的采用晶体管小信号等效电路来分析和计算。晶体管非线性特性,可用非线性跨导来描述。本文在分析LC振荡器工作过程后,引出非线性等效电路和输出电压计算方法。供工程设计时参考。     

变压器耦合LC正弦波振荡器的分析

在高频电子线路的教学中,变压器耦合反馈振荡器是LC正弦波振荡器中的重要内容。本文以常用的瞬时极性法分析了变压器耦合振荡电路的相位起振条件,以环路增益T的形式推导了振荡器的振幅起振条件,从而清晰地阐述了振荡器的工作原理,振幅起振条件及振荡频率与电路中各参数的关系。     

Theoretical Analysis of Novel Multi-Order LC Oscillators

A conventional differential pair LC oscillator is capable of generating only a single fundamental oscillation frequency. This brief presents the theoretical study of a novel oscillator that incorporates higher order LC filters to produce multiple oscillation frequencies that may be several octaves apart. These multiple oscillation frequencies are obtained from a single oscillator, thereby reducing the area of the circuit when being used for multistandard wireless applications. Moreover, a multi-order oscillator does not suffer from large parasitic capacitances from switches, which is a common drawback in switched-inductor tuned oscillators. A detailed analysis is carried out, and useful design insights are provided     

Linearly tunable quadrature oscillator derived from LC Colpitts structure using voltage differencing transconductance amplifier and adjustable current amplifier

The paper deals with an interesting oscillator solution derived from LC Colpitts circuit structure. Electronically controllable current gain of the current amplifier is utilized for driving of oscillation condition together with two transconductances in frame of voltage differencing transconductance amplifier for adjusting of frequency of oscillation. In the proposed structure these elements replace common bipolar transistor and metal coil. Designed circuit offers important advantages, i.e. absence of metal coil, quadrature outputs, amplitudes of generated signals independent of tuning process, linear electronic control of oscillation frequency (independent of oscillation condition). Implementation of circuit for amplitude stabilization and automatic control of oscillation condition for designed circuit is simple. These benefits are not available in classical LC Colpitts structures or in many well-known third-order oscillators. The theoretical conclusions are supported by experiments with behavioral representation employing commercially available devices and also by simulations using CMOS model.     

Design of an Optimized 2.5 GHz CMOS Differential LC Oscillator with Nonlinear Analysis for MOS Varactor

The oscillation amplitude and supply current relations for a differential CMOS oscillator are derived by using an analytic method. A simplified model to predict the phase noise performance of the oscillator is developed. The large signal analysis of a nonlinear inversion mode MOS varactor is presented. The derived expressions can help to design an optimized oscillator in terms of minimum phase noise and power consumption. The validity of the method has been verified by designing an LC CMOS oscillator in a 0.25 μm CMOS technology. The predictions are in good agreement with simulation results over a wide range of supply voltage.     

A New Low-Noise Dual-Band VCO for WLAN/WIMAX

In this paper, a new dual-band voltage-controlled oscillator (VCO) is proposed. The proposed VCO utilizes a fourth-order LC resonator that oscillates at two different frequencies. Moreover, its oscillation frequency can be chosen by switching the tail current between two different values. The switches are placed in a way that their resistances do not affect the quality factor of LC tanks, and phase noise does not increase. The proposed VCO is thoroughly analyzed by deriving a nonlinear model. The required conditions for oscillation and switching between two oscillation frequency bands are calculated approximately using averaging. Moreover, the VCO transient behavior in switching the oscillation frequency is investigated, and amplitudes of oscillation at two oscillation modes are calculated. The VCO is designed and simulated in \(0.18\,\upmu \hbox {m}\) CMOS technology to verify the design and analytical equations and to evaluate the performance of the proposed VCO. In comparison with the literature, proposed simulations show acceptable phase noise and transient behavior. In addition, the accuracy of the analytical equations is also verified.     

Optimised analytic designed 2.5 GHz CMOS VCO

An analytic method for prediction of oscillation amplitude and supply current of differential CMOS oscillators is presented. The validity of this method has been verified by designing an LC CMOS oscillator in a 0.24 /spl mu/m CMOS technology. The predictions are in good agreement with simulation results over a wide range of supply voltage.     

伪工作点与超宽带CMOS LC VCO设计

为了拓宽CMOS LC VCO的频率覆盖范围,很多工作都集中在扩展LC谐振回路中的电容覆盖.但通过对该VCO在调频状态下的分析表明,除了LC乘积的覆盖范围,在改变输出频率时维持交叉耦合MOS管的工作状态稳定也是获得宽带振荡器的条件之一.固定尺寸的交叉耦合MOS管结构不能满足后一个条件.将交叉耦合MOS管结构分为可开关调节的若干段可以有效地解决上述问题.通过VHF超宽频带CMOS LC VCO的具体设计表明,新电路结构可以获得突破性的频率覆盖.     

A 0.18 μm CMOS ring VCO for clock and data recovery applications

In this paper, a 3.125 GHz four stage voltage controlled ring oscillator is presented. The oscillator has been designed in a 0.18 μm CMOS process with a 1.8 V supply. Behavioral simulations predict an 18% tuning range for the oscillator, with −91 dBc/Hz phase noise at 1 MHz offset. Its power consumption has been simulated to be as low as 15.3 mW and the variation of its DC level of oscillation is 20 mV, which corresponds to 1.3% of its mean value. While consuming less area than an LC VCO, the proposed oscillator design achieves a more stable and reliable operation point.     

新型CMOS正交压控振荡器设计

通过对两个相同的LC振荡器进行交差耦合,用耦合系数来控制输出频率,设计了一种新型精准正交正弦波压控振荡器.由于其频率调节方式不再依赖于变容管,大大增加了输出频率的调节范围.基于TSMC18rf工艺库,采用Cadence的Spectre工具对电路进行仿真.在VDD=1.8V下,频率覆盖了1.78GHz到4.03GHz,可调控范围约为77%,1MHz处相位噪声约为-104dB/Hz.