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FCC E7D - 实用射频电路与滤波器

FCC 题库总览 > E级 (最高特级 Extra) > E7 实用射频电路与滤波器 > E7D

小节 E7D：实用射频电路与滤波器

本小节共包含 15 道中英双语精校考题
#E7D01🔗
How does a linear electronic voltage regulator work?
线性电子稳压器如何工作？
A
It has a ramp voltage as its output
它有一个斜坡电压作为其输出
B
It eliminates the need for a pass transistor
它消除了对传输晶体管的需要
C
The control element duty cycle is proportional to the line or load conditions
控制元件占空比与线路或负载条件成正比
D
The conduction of a control element is varied to maintain a constant output voltage
改变控制元件的导通以维持恒定的输出电压
✓ 正确答案
#E7D02🔗
How does a switchmode voltage regulator work?
开关模式稳压器如何工作？
A
By alternating the output between positive and negative voltages
通过在正电压和负电压之间交替输出
B
By varying the duty cycle of pulses input to a filter
通过改变滤波器输入脉冲的占空比
✓ 正确答案
C
By varying the conductivity of a pass element
通过改变传输元件的电导率
D
By switching between two Zener diode reference voltages
通过在两个齐纳二极管参考电压之间切换
#E7D03🔗
What device is used as a stable voltage reference?
使用什么器件作为稳定电压基准？
A
A Zener diode
齐纳二极管
✓ 正确答案
B
A digital-to-analog converter
数模转换器
C
An SCR
可控硅
D
An analog-to-digital converter
模数转换器
#E7D04🔗
Which of the following describes a three-terminal voltage regulator?
以下哪项描述了三端稳压器？
A
A series current source
串联电流源
B
A series regulator
A系列调节器
✓ 正确答案
C
A shunt regulator
并联调节器
D
A shunt current source
分流电流源
#E7D05🔗
Which of the following types of linear voltage regulator operates by loading the unregulated voltage source?
以下哪种类型的线性稳压器通过加载未稳压的电压源来工作？
A
A constant current source
恒流源
B
A series regulator
A系列调节器
C
A shunt current source
分流电流源
D
A shunt regulator
并联调节器
✓ 正确答案
#E7D06🔗
What is the purpose of Q1 in the circuit shown in Figure E7-2?
图 E7-2所示电路中Q1的作用是什么？
Figure for E7D06
A
It provides negative feedback to improve regulation
它提供负反馈以改善监管
B
It provides a constant load for the voltage source
它为电压源提供恒定负载
C
It controls the current to keep the output voltage constant
它控制电流以保持输出电压恒定
✓ 正确答案
D
It provides regulation by switching or “chopping” the input DC voltage
它通过切换或“斩波”输入直流电压来提供调节
#E7D07🔗
What is the purpose of C2 in the circuit shown in Figure E7-2?
图 E7-2所示电路中C2的作用是什么？
Figure for E7D07
A
It bypasses rectifier output ripple around D1
它绕过 D1 周围的整流器输出纹波
✓ 正确答案
B
It is a brute force filter for the output
它是输出的强力过滤器
C
To prevent self-oscillation
防止自激振荡
D
To provide fixed DC bias for Q1
为Q1提供固定直流偏置
#E7D08🔗
What type of circuit is shown in Figure E7-2?
图 E7-2 所示的电路是什么类型？
Figure for E7D08
A
Switching voltage regulator
开关稳压器
B
Common emitter amplifier
共发射极放大器
C
Linear voltage regulator
线性稳压器
✓ 正确答案
D
Common base amplifier
共基极放大器
#E7D09🔗
How is battery operating time calculated?
电池工作时间是如何计算的？
A
Average current divided by capacity in amp-hours
平均电流除以安培小时容量
B
Average current divided by internal resistance
平均电流除以内阻
C
Capacity in amp-hours divided by average current
容量（安培小时）除以平均电流
✓ 正确答案
D
Internal resistance divided by average current
内阻除以平均电流
#E7D10🔗
Why is a switching type power supply less expensive and lighter than an equivalent linear power supply?
为什么开关型电源比同等的线性电源更便宜且更轻？
A
The inverter design does not require an output filter circuit
逆变器设计不需要输出滤波电路
B
The control circuitry uses less current, therefore smaller heat sinks are required
控制电路使用较少的电流，因此需要较小的散热器
C
The high frequency inverter design uses much smaller transformers and filter components for an equivalent power output
高频逆变器设计使用更小的变压器和滤波器元件来实现等效功率输出
✓ 正确答案
D
It recovers power from the unused portion of the AC cycle, thus using fewer components
它从交流周期的未使用部分恢复电力，从而使用更少的元件
#E7D11🔗
What is the purpose of an inverter connected to a solar panel output?
连接到太阳能电池板输出的逆变器的用途是什么？
A
Reduce AC ripple on the output
减少输出上的交流纹波
B
Maintain voltage with varying illumination levels
在不同的照明水平下保持电压
C
Prevent discharge when panel is not illuminated
防止面板未发光时放电
D
Convert the panel’s output from DC to AC
将面板的输出从直流转换为交流
✓ 正确答案
#E7D12🔗
What is the dropout voltage of a linear voltage regulator?
线性稳压器的压差是多少？
A
Minimum input voltage for rated power dissipation
额定功耗的最小输入电压
B
Maximum output voltage drop when the input voltage is varied over its specified range
输入电压在指定范围内变化时的最大输出电压降
C
Minimum input-to-output voltage required to maintain regulation
维持调节所需的最小输入到输出电压
✓ 正确答案
D
Maximum that the output voltage may decrease at rated load
额定负载时输出电压可能降低的最大值
#E7D13🔗
Which of the following calculates power dissipated by a series linear voltage regulator?
以下哪一项计算串联线性稳压器的功耗？
A
Input voltage multiplied by input current
输入电压乘以输入电流
B
Input voltage divided by output current
输入电压除以输出电流
C
Voltage difference from input to output multiplied by output current
输入到输出的电压差乘以输出电流
✓ 正确答案
D
Output voltage multiplied by output current
输出电压乘以输出电流
#E7D14🔗
What is the purpose of connecting equal-value resistors across power supply filter capacitors connected in series?
电源滤波电容两端串联等值电阻的目的是什么？
A
Equalize the voltage across each capacitor
均衡每个电容器上的电压
B
Discharge the capacitors when voltage is removed
电压移除后对电容器进行放电
C
Provide a minimum load on the supply
提供最小的电源负载
D
All these choices are correct
所有这些选项都是正确的
✓ 正确答案
#E7D15🔗
What is the purpose of a step-start circuit in a high-voltage power supply?
高压电源中的步进启动电路的用途是什么？
A
To provide a dual-voltage output for reduced power applications
为低功耗应用提供双电压输出
B
To compensate for variations of the incoming line voltage
补偿进线电压的变化
C
To prevent arcing across the input power switch or relay contacts
防止输入电源开关或继电器触点产生电弧
D
To allow the filter capacitors to charge gradually
让滤波电容逐渐充电
✓ 正确答案
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