求电路图讲解，输入正弦波频率很高，经过2级晶体管放大，其中有2级单调谐振，波形变成了如图示的样子。。

用英文解释正弦波谐振电路的电路组成和原理~

我原来就想直接把网址弄下来，但是BD不让我发。说我的内容里有广告~~


这是我自己找的，里面有很多的公式，没办法粘过来，你自己琢磨琢磨，看看是什么公式

RLC circuit
An RLC circuit (also known as a resonant circuit, tuned circuit, or LCR circuit) is an electrical circuit consisting of a resistor (R), an inductor (L), and a capacitor (C), connected in series or in parallel. This configuration forms a harmonic oscillator.

Tuned circuits have many applications particularly for oscillating circuits and in radio and communication engineering. They can be used to select a certain narrow range of frequencies from the total spectrum of ambient radio waves. For example, AM/FM radios with analog tuners typically use an RLC circuit to tune a radio frequency. Most commonly a variable capacitor is attached to the tuning knob, which allows you to change the value of C in the circuit and tune to stations on different frequencies.

An RLC circuit is called a second-order circuit as any voltage or current in the circuit can be described by a second-order differential equation for circuit analysis.

Configurations
Every RLC circuit consists of two components: a power source and resonator. There are two types of power sources – Thévenin and Norton. Likewise, there are two types of resonators – series LC and parallel LC. As a result, there are four configurations of RLC circuits:

Series LC with Thévenin power source
Series LC with Norton power source
Parallel LC with Thévenin power source
Parallel LC with Norton power source.
It is relatively easy to show that each of the two series configurations can be transformed into the other using elementary network transformations – specifically, by transforming the Thévenin power source to the equivalent Norton power source, or vice versa. Likewise, each of the two parallel configurations can be transformed into the other using the same network transformations. Finally, the Series/Thévenin and the Parallel/Norton configurations are dual circuits of one another. Likewise, the Series/Norton and the Parallel/Thévenin configurations are also dual circuits.


[edit] Similarities and differences between series and parallel circuits
The expressions for the bandwidth in the series and parallel configuration are inverses of each other. This is particularly useful for determining whether a series or parallel configuration is to be used for a particular circuit design. However, in circuit analysis, usually the reciprocal of the latter two variables is used to characterize the system instead. They are known as the resonant frequency and the Q factor respectively.


[edit] Fundamental parameters
There are two fundamental parameters that describe the behavior of RLC circuits: the resonant frequency and the attenuation (or, alternatively, the damping factor). In addition, other parameters derived from these first two are discussed below.


[edit] Resonant frequency
The undamped resonant frequency of an RLC circuit (in radians per second) is given by


In the more familiar unit hertz (or cycles per second), the resonant frequency becomes


Resonance occurs when the complex impedance ZLC of the LC resonator becomes zero:


Both of these impedances are functions of angular frequency ω:



Setting the magnitude of the impedance to be zero at ω = ω0 and using j2 = − 1:




[edit] Attenuation
The attenuation α is defined as


for the series RLC circuit, and


for the parallel RLC circuit.





[edit] Damping factor
The damping factor ζ is the ratio of the attenuation α to the resonant frequency ω0 :


for a series RLC circuit, and:


for a parallel RLC circuit.

It is sometimes more convenient to use the damping factor, which is dimensionless, instead of the attenuation factor, which has dimensions of radians per second, to analyze the properties of a resonant circuit.


[edit] Minimizing the attenuation for oscillator circuits
For applications in oscillator circuits, it is generally desirable to make the attenuation (or equivalently, the damping factor) as small as possible. In practice, this objective requires making the circuit's resistance R as small as physically possible for a series circuit, or alternatively increasing R to as much as as possible for a parallel circuit. In either case, the RLC circuit becomes a good approximation to an ideal LC circuit.

Alternatively, for applications in bandpass filters, the value of the damping factor is chosen based on the desired bandwidth of the filter. For a wider bandwidth, a larger value of the damping factor is required (and vice versa). In practice, this requires adjusting the relative values of the resistor R and the inductor L in the circuit.


[edit] Derived parameters
The derived parameters include bandwidth, Q factor, and damped resonance frequency.


[edit] Bandwidth
The RLC circuit may be used as a bandpass or band-stop filter by replacing R with a receiving device with the same input resistance. In the Series case the bandwidth (in radians per second) is


Alternatively, the bandwidth in hertz is


The bandwidth is a measure of the width of the frequency response at the two half-power frequencies. As a result, this measure of bandwidth is sometimes called the full-width at half-power. Since electrical power is proportional to the square of the circuit voltage (or current), the frequency response will drop to at the half-power frequencies.


[edit] Damped resonance
The damped resonance frequency can be expressed in terms of the undamped resonance frequency and the damping factor. If the circuit is underdamped, meaning


or equivalently


then we can define the damped resonance as


In an oscillator circuit

.
or equivalently

.

As a result

.
See discussion of underdamping, overdamping, and critical damping, below.


[edit] Circuit analysis

[edit] Series RLC with Thévenin power source
In this circuit, the three components are all in series with the voltage source.

Series RLC Circuit notations:

v - the voltage of the power source (measured in volts V)
i - the current in the circuit (measured in amperes A)
R - the resistance of the resistor (measured in ohms = V/A);
L - the inductance of the inductor (measured in henrys = H = V·s/A)
C - the capacitance of the capacitor (measured in farads = F = C/V = A·s/V)
q - the charge across the capacitor (measured in coulombs C)

Given the parameters v, R, L, and C, the solution for the charge, q, can be found using Kirchhoff's voltage law. (KVL) gives


For a time-changing voltage v(t), this becomes


Using the relationship between charge and current:


The above expression can be expressed in terms of charge across the capacitor:


Dividing by L gives the following second order differential equation:


We now define two key parameters:

and

Substituting these parameters into the differential equation, we obtain:


or



[edit] Frequency domain
The series RLC can be analyzed in the frequency domain using complex impedance relations. If the voltage source above produces a complex exponential wave form with complex amplitude V(s) and angular frequency s = σ + iω , KVL can be applied:


where I(s) is the complex current through all components. Solving for I(s):


And rearranging, we have at



[edit] Complex admittance
Next, we solve for the complex admittance Y(s):


Finally, we simplify using parameters α and ωo


Notice that this expression for Y(s) is the same as the one we found for the Zero State Response.


[edit] Poles and zeros
The zeros of Y(s) are those values of s such that Y(s) = 0:

and
The poles of Y(s) are those values of s such that . By the quadratic formula, we find


Notice that the poles of Y(s) are identical to the roots λ1 and λ2 of the characteristic polynomial.


[edit] Sinusoidal steady state
If we now let s = iω....

Taking the magnitude of the above equation:


Next, we find the magnitude of current as a function of ω


If we choose values where R = 1 ohm, C = 1 farad, L = 1 henry, and V = 1.0 volt, then the graph of magnitude of the current i (in amperes) as a function of ω (in radians per second) is:


Sinusoidal steady-state analysis
Note that there is a peak at imag(ω) = 1. This is known as the resonant frequency. Solving for this value, we find:



[edit] Parallel RLC circuit
Parallel RLC Circuit notations:

V - the voltage of the power source (measured in volts V)
I - the current in the circuit (measured in amperes A)
R - the resistance of the resistor (measured in ohms = V/A);
L - the inductance of the inductor (measured in henrys = H = V·s/A)
C - the capacitance of the capacitor (measured in farads = F = C/V = A·s/V)

The complex admittance of this circuit is given by adding up the admittances of the components:


The change from a series arrangement to a parallel arrangement has some very real consequences for the behaviour. This can be seen by plotting the magnitude of the current . For comparison with the earlier graph we choose values where R = 1 ohm, C = 1 farad, L = 1 henry, and V = 1.0 volt and ω in radians per second:


Sinusoidal steady-state analysis
There is a minimum in the frequency response at the resonant frequency .

A parallel RLC circuit is a example of a band-stop circuit response that can be used as a filter to block frequencies at the resonance frequency but allow others to pass.

图中所示为RLC串联谐振电路，具有选频特性，相当于是一个带通滤波器。谐振频率就是滤波器的中心频率。f0=1/2π√LC。
而方波包含了丰富的谐波，谐波频率为方波频率的2k+1倍，k=1,2,3...
只要调整L、C的参数，使f0=1/2π√LC等于方波频率的奇数倍，但不等于方波频率，就可以得到与方波频率不同的正弦波。

没看到电路图，不敢确定。
感觉似乎跟晶体管偏置有关，而且产生了寄生高频振荡。

另一个问题：图中频率最低的正弦波，是不是输入的电压波形？

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美兰区13062752703： 正弦波产生电路,频率1KHZ,幅值1V.求最简单的电路 - ？
范常苗壮：[答案] 采用一个运算放大器和4只电阻,2只电容,就可以构建正弦波产生电路.具体电路如下: 频率计算参见公式,幅值大小可通过调整RF改变.

美兰区13062752703： 理论上微分电路输入正弦波信号的幅值随着频率变大而大,但是频率高到一定值后又逐渐变小了,这是为什么 - ？
范常苗壮： 可能原因 1)电容器的高频特性变化,频率高时电容的等效电路变成电感; 2)运放的频率特性,高频时增益下降.

美兰区13062752703： 正弦波振荡电路当频率很高时为什么要采用共基放大电路? - ？
范常苗壮： 基极在三极管中处于中部位置,将基极和地线交流连接,等于将发射级、集电极进行了静电屏蔽,这样影响三极管截止频率的最大因素Ccb被设计掉了.共基电路在三极管三种放大器状态中拥有最高的频率响应

美兰区13062752703： 模电正弦波振荡电路？
范常苗壮：1.上正下负;2.Rp+R2>10.2KΩ;3.f≈1.6KHz 首先观察这图是典型的RC桥式振荡,你看上面的为Rc串并联选频网络在正反馈一侧,下面R1,R2,Rp一定引入的负反馈,起振后,RC选频网络从输出端采集的信号反馈到输入端做输入信号,与负反馈网络构成同相比例运算.所以运放上“+”下“—”,而RC串并联网络的反馈系数为3,为满足AF>1的幅值条件,A>3,而Rc选频网络做输入信号看做整体与上面的构成同相比例,故其放大倍数Af=1+(Rp+R2)/R1>3,解得Rp+R2>10.2KΩ.振荡频率f=1/2πRC约为1.6KHz..分析完毕,望采纳

美兰区13062752703： 求交流正弦波转方波电路图,最好附带参数 - ？
范常苗壮： 用74HC04、74AHC04、74HC14、74AHC14、CD4069等反相器都可以简单地实现把各种波形整形为矩形波,如果是正弦波这样的对称波形,整形后的输出就是方波.如果输入电压幅值范围跨越正负,那么在输入信号和反相器的输入之间要加隔直电容耦合并且还要加偏置电压电路.一般经过一次反相后就可以得到矩形波,最多经两次反相后就可以得到质量非常好的矩形波.74HC14、74AHC14这样的施密特反相器效果更好,具有去掉波形中的高频寄生波(毛刺)的作用. 如下图(R1=R2)——

美兰区13062752703： 求一个能向外提供稳定1MHz的正弦波的震荡电路 给出具体参数 最好能够给出解释,谢谢! - ？
范常苗壮： 找一个1MHz的石英晶体震荡器,用它来构成频率非常稳定的振荡器,然后用LC电路滤网输出.PNP型三极管9012与1MHz石英晶体构成三点式振荡器,其中51pF可调电容和晶振组成等效LC电路,晶振工作在偏感性状态.经220pF电容与115μH电感组成的并联谐振电路选频、波形整形后,输出1MHz正弦信号. 微调51pF电容可以调整振荡频率,调整115μH电感使输出最强.

美兰区13062752703： 求400hz正弦波的lc滤波电路 最好有计算过程 - ？
范常苗壮： 在multisim中的 这里面有自动计算设计,希望对你有帮助

美兰区13062752703： 正弦波振荡电路,求大神给参数,让频率稳定在10KHz~100KHz - ？
范常苗壮： 按照比例更改所有与频率相关的元件参数,说白了就是改电容、电感.比如说要把频率减小10倍,请把所有的C都增大10倍、所有的L都减小10倍就解决了.至于频率稳定问题,只要原来是稳定的,新改动的也一样稳定. 当然如果要增大频率,除了C、L之外还要考虑晶体管的截止频率是否足够,减小频率时不会有问题.

美兰区13062752703： 正弦波发生电路 - ？
范常苗壮： 一般的思路是这样:1、首先在前级设计出10kHz—60kHz频率可调的正弦波低频振荡器,一般可以用文氏桥振荡器,它调节简单,波形较好.2、振荡器的输出接放大器,实际就象音频功放.不过它的频响要达到60KHZ以上(一般功放达不到),你可能并不需要大的功率,所以在末级不需要大功率管,一般小、中功率管,耐压只要够就行.3、对于末级的电压要高,否则输出不了150V峰峰值,你应该使用大于±150V的电源供电.4、输出幅度调整,可放在电压放大级,象音量控制一样,用电位器,并在上、下端加接电阻,以控制最下端输出30V,最上下端输出在150V.大概就这样.

美兰区13062752703： 怎样实现一个频率可调,相对简单,输出频率尽可能大的正弦波发生电路. - ？
范常苗壮： 建议使用NE555做方波发生器,在2脚引出电容的充电放电信号做放大之后稍作波形修改就是正弦波波形.调节2脚和7脚之间电阻就可以实现平滑频率调节.3脚引出做频率显示.