FCC E7B - 实用射频电路与滤波器

#E7B01🔗

For what portion of the signal cycle does each active element in a push-pull, Class AB amplifier conduct?

推挽式 AB 类放大器中的每个有源元件在信号周期的哪一部分导通？

More than 180 degrees but less than 360 degrees

大于180度但小于360度

✓ 正确答案

Exactly 180 degrees

正好180度

The entire cycle

整个周期

Less than 180 degrees

小于180度

#E7B02🔗

What is a Class D amplifier?

什么是 D 类放大器？

An amplifier that uses switching technology to achieve high efficiency

使用开关技术实现高效率的放大器

✓ 正确答案

A low power amplifier that uses a differential amplifier for improved linearity

使用差分放大器来提高线性度的低功率放大器

An amplifier that uses drift-mode FETs for high efficiency

使用漂移模式 FET 实现高效率的放大器

An amplifier biased to be relatively free from distortion

放大器偏置相对无失真

#E7B03🔗

What circuit is required at the output of an RF switching amplifier?

射频开关放大器的输出端需要什么电路？

A filter to remove harmonic content

去除谐波含量的滤波器

✓ 正确答案

A high-pass filter to compensate for low gain at low frequencies

用于补偿低频低增益的高通滤波器

A matched load resistor to prevent damage by switching transients

匹配的负载电阻可防止开关瞬变造成损坏

A temperature compensating load resistor to improve linearity

用于提高线性度的温度补偿负载电阻

#E7B04🔗

What is the operating point of a Class A common emitter amplifier?

A 类共发射极放大器的工作点是多少？

Approximately halfway between saturation and cutoff

大约在饱和度和截止值之间

✓ 正确答案

Approximately halfway between the emitter voltage and the base voltage

大约在发射极电压和基极电压之间

At a point where the bias resistor equals the load resistor

在偏置电阻等于负载电阻的点处

At a point where the load line intersects the zero bias current curve

在负载线与零偏置电流曲线相交的点处

#E7B05🔗

What can be done to prevent unwanted oscillations in an RF power amplifier?

如何防止射频功率放大器中出现不必要的振荡？

Tune the stage for minimum loading

调整平台以实现最小负载

Tune both the input and output for maximum power

调整输入和输出以获得最大功率

Install parasitic suppressors and/or neutralize the stage

安装寄生抑制器和/或中和舞台

✓ 正确答案

Use a phase inverter in the output filter

在输出滤波器中使用反相器

#E7B06🔗

What is a characteristic of a grounded-grid amplifier?

接地栅极放大器有什么特点？

High power gain

高功率增益

Low input impedance

低输入阻抗

✓ 正确答案

High electrostatic damage protection

高静电损坏防护

Low bandwidth

低带宽

#E7B07🔗

Which of the following is the likely result of using a Class C amplifier to amplify a single-sideband phone signal?

使用 C 类放大器放大单边带电话信号可能会出现以下哪项结果？

Reduced intermodulation products

减少互调产物

Increased overall intelligibility

提高整体清晰度

Reduced third-order intermodulation

减少三阶互调

Signal distortion and excessive bandwidth

信号失真和带宽过大

✓ 正确答案

#E7B08🔗

Why are switching amplifiers more efficient than linear amplifiers?

为什么开关放大器比线性放大器更高效？

Switching amplifiers operate at higher voltages

开关放大器在较高电压下工作

The switching device is at saturation or cutoff most of the time

开关器件大部分时间处于饱和或截止状态

✓ 正确答案

Linear amplifiers have high gain resulting in higher harmonic content

线性放大器具有高增益，导致谐波含量更高

Switching amplifiers use push-pull circuits

开关放大器采用推挽电路

#E7B09🔗

What is characteristic of an emitter follower (or common collector) amplifier?

射极跟随器（或共集电极）放大器有什么特点？

Low input impedance and phase inversion from input to output

低输入阻抗和从输入到输出的反相

Differential inputs and single output

差分输入和单路输出

Acts as an OR circuit if one input is grounded

如果一个输入接地，则充当 OR 电路

Input and output signals in-phase

输入和输出信号同相

✓ 正确答案

#E7B10🔗

In Figure E7-1, what is the purpose of R1 and R2?

图 E7-1中，R1和R2的作用是什么？

Load resistors

负载电阻

Voltage divider bias

分压器偏置

✓ 正确答案

Self bias

自我偏见

Feedback

反馈意见

#E7B11🔗

In Figure E7-1, what is the purpose of R3?

在图 E7-1中，R3的用途是什么？

Fixed bias

固定偏差

Emitter bypass

发射极旁路

Output load resistor

输出负载电阻

Self bias

自我偏见

✓ 正确答案

#E7B12🔗

What type of amplifier circuit is shown in Figure E7-1?

图 E7-1 所示的放大器电路是什么类型？

Common base

共同基地

Common collector

普通收集器

Common emitter

共发射极

✓ 正确答案

Emitter follower

射极跟随器

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FCC E7B - 实用射频电路与滤波器

小节 E7B：实用射频电路与滤波器