1、Unit Electronic Circuit and Its ApplicationLesson 7 FiltersNew Words filter filt n. 滤波器 modify mdifai vt. 更改, 修改 eliminate ilimineit vt. 排除, 消除, 除去 regulation ,rejulein n.规则, 调节, 校准 crystal kristl n. 水晶, 结晶, 晶体 ceramic sirmik a. & n. 陶器的, 陶瓷 categorize ktiraiz v. 加以类别, 分 类 bandpass bndp:s n. 带通 high
2、pass n. 高通 lowpass n. 低通Phrases and Expressions passive filter 无源滤波器 active filter 有源滤波器Notes1.A filter is a passive or active circuit designed primarily for the purpose of modifying a signal or source of power. 滤波器包括无源滤波器和有源滤波器，它们主要是为了改变信号或电源输出而设计的。 句中designedor source of power 是过去分词短语，充当定语，修饰circu
3、it。2.In power supply, the filter is network of capacitors, resistor and inducts that eliminates the rectifier. 在电源中，滤波器由电容、电阻、与电感组网而成，从而代替了整流器。 is network of相当于consist of，意思是“由组成”；定语从句that eliminates the rectifier 修饰 the filter。3.Filter are used in communications practice to eliminate energy at some
4、 frequencies while allowing energy at other frequencies to pass with little or no attenuation. 在通信系统中，滤波器主要用来滤除某些频率成分而允许另一些频率成分无衰减地通过。 不定式to eliminate energy at some frequencies充当主语补足语； while后接现在分词短语，表示轻微转折。4.Such filters, if passive, are constructed using capacitors, inductor and sometimes resistor
5、s. 句中if passive省略了主谓部分，即they are。5.Active filters generally utilize operational amplifiers. 句中utilize意为“利用”，相当于use。6.Filters can be categorized, in terms of their frequency response characteristics, into four groups. to categorize into 相当于to classify into或group into，“把分成”； in terms of相当于according to
6、。7.The highpass filter allows only the signals above a certain frequencies to pass. 高通滤波器只允许高于某个频率的信号通过。句中certain表示某种模糊概念，“某种，某个”。 8.Some are designed to use at radio frequencies, while others operate at audio frequencies. 有的用于射频，有的用于音频。 while others operate at audio frequencies中省略了are designed to，其
7、中while表示轻微转折。Translation of TextsLesson 7 Filters A filter is a passive or active circuit designed primarily for the purpose of modifying a signal or source of power. A passive filter requires no power for its operation, and always has a certain amount of loss. An active filter requires its own powe
8、r, but may provide gain.第第7课课 滤波器滤波器 滤波器包括无源滤波器和有源滤波器，它们主要是为了改变信号而设计的。无源滤波器不需要电源就可以工作且会有一定的损耗。有源滤波器则需要电源且能提供功率增益。 In power supply, the filter is network of capacitors, resistor and inducts that eliminates the rectifier. A good power supply filter will produce a smooth direct current output under var
9、iable load conditions, with good regulation. 在电源中，滤波器由电容、晶体管和电感组成，用以消除来自于整流器的直流电流的波动。好的电源滤波器能够在负载可变及好的稳压条件下获得平滑的直流输出电流。 Filter are used in communications practice to eliminate energy at some frequencies while allowing energy at other frequencies to pass with little or no attenuation. Such filters, i
10、f passive, are constructed using capacitors, inductor and sometimes resistors. Active filters generally utilize operational amplifiers(as shown in Fig.7-1). 在通信系统中，滤波器主要用来滤除某些频率成分而允许另一些频率成分无衰减地通过。如果是无源滤波器，则由电容、电感、晶体管构成；有源滤波器，则由运算放大器构成（如图7-1所示）。 Amplifiers included in a filter design can be used to i
11、mprove the performance of a filter, while avoiding the need for inductors (which are typically expensive compared to other components). An amplifier also can prevent the load impedance of the following stage from affecting the characteristics of the filter. An active filter can have complex poles an
12、d zeros without using a bulky or expensive inductor. The shape of the response, the Q (quality factor), and the tuned frequency can often be set with inexpensive variable resistors. 在滤波器设计中，放大器可以用来提高滤波器的性能，同时避免了必须使用电感器（这相对于其他组成部分而言通常是昂贵的）。放大器还可以防止下一级负载阻抗对滤波器特性的影响。有源滤波器即使不使用笨重的或昂贵的电感器也可以通过调节廉价的可变电阻器来
13、设置。 Mechanical filters make use of the resonant properties of certain substances. Crystal and ceramic filters use piezoelectric materials to obtain the desired frequency response. 机械滤波器由某些具有谐振特性的材料制成，晶体滤波器和陶瓷滤波器采用具有压电特性的材料以获得理想的频率响应。 Filters can be categorized, in terms of their frequency response c
14、haracteristics, into four groups. The bandpass filter allows signal between two predetermined frequencies to pass, but attenuates all other frequencies. The band-rejection or bandstop filter eliminates all energy between two frequencies, and allows signals outside the limit frequencies to pass. 滤波器根
15、据其频率响应特性可分为4种类型。带通滤波器允许两个预定频率之间的信号通过而衰减其他频率的信号。带阻滤波器禁止两个频率之间的信号通过而允许两个频率之外的所有信号通过。 The highpass filter allows only the signals above a certain frequencies to pass. The lowpass filer allows only the signals below a certain frequency to pass. The actual response characteristics of all four types of fi
16、lter are highly variable, and depend on many different factors. Selective filers are employed in both transmitting and receiving applications. Some are designed for use at radio frequencies, while others operate at audio frequencies. 高通滤波器只允许高于某个频率的信号通过，低通滤波器只允许低于某个频率的信号通过。4种滤波器的实际频率特性都是依赖许多不同的因素而变化
17、的。滤波器广泛地用于发射机和接收机，有的用于射频，有的用于音频。Exercises1.Write T (True) or F (False) beside the following statements about the text.a.A passive filter requires power for its operation, and always has a certain amount of loss.b.An active filter requires its own power, but may provide gain.c.In power supply, the fi
18、lter is network of capacitors, resistor and inducts.d.A good power supply filter will produce a smooth direct current output under variable load conditions, with good regulation.e.Filter is used in communications practice to eliminate energy at some frequencies while allowing energy at other frequen
19、cies to pass with little or no attenuation.f.Such filters, if passive, are constructed using resistors, inductor and sometimes capacitors.g.The band-rejection or bandstop filter eliminates all energy between two frequencies, and allows signals outside the limit frequencies to pass.h.Selective filers
20、 are employed in both transmitting and receiving applications.2.Match the following terms to appropriate definition or expression.a. a filter 1. allows signal between two predetermined frequencies to passb. the highpass filter 2. allows the signals below a certain frequency to pass c. the lowpass fi
21、ler 3. eliminates all energy between two frequenciesd. the bandpass filter 4. allows the signals above a certain frequencies to passe. the band-rejection filter 5. a passive or active circuit designed primarily for the purpose of modifying a signal or source of power. 3.Fill in the missing words acc
22、ording to the text.a.A filter is a or circuit designed primarily for the purpose of modifying a signal or source of power. b.In power supply, the filter is network of , and that eliminates the rectifier. A good power supply filter will produce a smooth direct current output under variable load condi
23、tions, with good regulation. c.Such filters, if passive, are constructed using , and sometimes . d.Some are designed for use at frequencies, while others operate at frequencies. 4. Translate the following sentences into English.无源滤波器由电阻、电容、电感组成。有源滤波器由集成运放组成。滤波器按其频率特性可分为高通滤波器、低通滤波器、带通滤波器和带阻滤波器。滤波器主要用来滤除某些频率成分而允许另一些频率成分无衰减地通过。滤波器可用于射频也可用于音频。End
