How many different input levels can be encoded by an analog-to-digital converter with 8-bit resolution?
The correct answer is D: 256. An analog-to-digital converter with 8-bit resolution can encode 256 different input levels. The number of levels equals 2 raised to the power of the number of bits.
For an 8-bit ADC: 2^8 = 256 levels. This means the ADC can distinguish 256 different voltage levels between its minimum and maximum input range. The resolution determines how finely the ADC can quantize the input signal. More bits mean more levels and finer resolution. An 8-bit ADC divides the input range into 256 steps, while a 10-bit ADC would have 1024 steps (2^10), and a 12-bit ADC would have 4096 steps (2^12).
Exam Tip
8-bit ADC levels = 2^8 = 256. Remember: An N-bit ADC can encode 2^N different levels. For 8 bits, that's 2^8 = 256 levels.
Memory Aid
"**8**-bit **A**DC = **2**^**8** = **256** levels (think '8A = 2^8 = 256')"
Real-World Application
You're using an 8-bit ADC in your circuit. The ADC can distinguish 256 different voltage levels. If the input range is 0-5 volts, each level represents about 19.5 millivolts (5V / 256). This resolution determines how accurately the ADC can represent the input signal.
FCC Part 97.3Key Concepts
Why Other Options Are Wrong
Option A: Incorrect. 8 is the number of bits, not the number of levels. The number of levels is 2^8 = 256.
Option B: Incorrect. The number of levels is fixed by the bit resolution (2^8 = 256), not multiplied by amplifier gain. Gain affects the input range, not the number of quantization levels.
Option C: Incorrect. The number of levels is 256, not divided by gain. Gain affects what voltage range the 256 levels cover, but doesn't change the number of levels.
题目解析
The correct answer is D: 256. An analog-to-digital converter with 8-bit resolution can encode 256 different input levels. The number of levels equals 2 raised to the power of the number of bits. For an 8-bit ADC: 2^8 = 256 levels. This means the ADC can distinguish 256 different voltage levels between its minimum and maximum input range. The resolution determines how finely the ADC can quantize the input signal. More bits mean more levels and finer resolution. An 8-bit ADC divides the input range into 256 steps, while a 10-bit ADC would have 1024 steps (2^10), and a 12-bit ADC would have 4096 steps (2^12).
考试技巧
8-bit ADC levels = 2^8 = 256. Remember: An N-bit ADC can encode 2^N different levels. For 8 bits, that's 2^8 = 256 levels.
记忆口诀
**8**-bit **A**DC = **2**^**8** = **256** levels (think '8A = 2^8 = 256')
实际应用示例
You're using an 8-bit ADC in your circuit. The ADC can distinguish 256 different voltage levels. If the input range is 0-5 volts, each level represents about 19.5 millivolts (5V / 256). This resolution determines how accurately the ADC can represent the input signal.
错误选项分析
Option A: Incorrect. 8 is the number of bits, not the number of levels. The number of levels is 2^8 = 256. Option B: Incorrect. The number of levels is fixed by the bit resolution (2^8 = 256), not multiplied by amplifier gain. Gain affects the input range, not the number of quantization levels. Option C: Incorrect. The number of levels is 256, not divided by gain. Gain affects what voltage range the 256 levels cover, but doesn't change the number of levels.
知识点
ADC resolution, 8-bit ADC, Quantization levels, 2^N levels
Verified Content
Question from official FCC Extra Class question pool. Explanation reviewed by licensed amateur radio operators.