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Questions and Answers
What is necessary for a continuous variable to be processed by a digital computer?
What is necessary for a continuous variable to be processed by a digital computer?
- It must be converted to a discrete form. (correct)
- It must be stored in its exact form.
- It must be represented as an analog signal.
- It must have a finite number of bits.
Which of the following describes an analog signal?
Which of the following describes an analog signal?
- Continuous amplitude and continuous time. (correct)
- Discrete amplitude and discrete time.
- Continuous amplitude and discrete time.
- Discrete amplitude and continuous time.
What does the Nyquist theorem state regarding sampling frequency?
What does the Nyquist theorem state regarding sampling frequency?
- Sampling frequency must be greater than or equal to 2 times the maximum frequency of the signal. (correct)
- Sampling frequency must equal the maximum frequency of the signal.
- Sampling frequency can be any value regardless of the signal frequency.
- Sampling frequency must be less than 2 times the maximum frequency of the signal.
What is aliasing in the context of signal processing?
What is aliasing in the context of signal processing?
Which type of signal do most transducers produce?
Which type of signal do most transducers produce?
What is the relationship between the digital input and the analog output in a Digital to Analog converter?
What is the relationship between the digital input and the analog output in a Digital to Analog converter?
In a two-bit digital to analog converter, what is the value of Vo when both V1 and V2 are at 0 volts?
In a two-bit digital to analog converter, what is the value of Vo when both V1 and V2 are at 0 volts?
What voltage represents the binary input 111 in a three-bit digital to analog converter when V equals 8 volts?
What voltage represents the binary input 111 in a three-bit digital to analog converter when V equals 8 volts?
How is the output voltage Vo calculated in a two-bit converter circuit?
How is the output voltage Vo calculated in a two-bit converter circuit?
What is the step size in a digital to analog converter dependent on?
What is the step size in a digital to analog converter dependent on?
In a three-bit converter, what output corresponds to the digital input 010 when the maximum input voltage V is chosen as 8 volts?
In a three-bit converter, what output corresponds to the digital input 010 when the maximum input voltage V is chosen as 8 volts?
Which color code is assigned to the ground in circuit representations?
Which color code is assigned to the ground in circuit representations?
When using the Tinkercad simulation, the positive supply voltage 1 is indicated by which color?
When using the Tinkercad simulation, the positive supply voltage 1 is indicated by which color?
What characteristic of operational amplifiers allows them to not alter the effective external electrical components connected to their input?
What characteristic of operational amplifiers allows them to not alter the effective external electrical components connected to their input?
In a closed-loop configuration of an operational amplifier, what is fed back into the input?
In a closed-loop configuration of an operational amplifier, what is fed back into the input?
What is a defining feature of flash/parallel ADC converters compared to successive/serial ADCs?
What is a defining feature of flash/parallel ADC converters compared to successive/serial ADCs?
What is the resolution of an ADC?
What is the resolution of an ADC?
Which of the following statements about serial transmission is correct?
Which of the following statements about serial transmission is correct?
What does the term 'sampling frequency' refer to in the context of ADC?
What does the term 'sampling frequency' refer to in the context of ADC?
What is the bit rate of a system sampling at 8000 samples/s with 4 bits per sample?
What is the bit rate of a system sampling at 8000 samples/s with 4 bits per sample?
What is the primary purpose of the SAR (successive approximation register) in ADC converters?
What is the primary purpose of the SAR (successive approximation register) in ADC converters?
What does quantization error represent in a digital signal system?
What does quantization error represent in a digital signal system?
How is the quantization step calculated for an 8-bit digital signal ranging from 0 to 10 volts?
How is the quantization step calculated for an 8-bit digital signal ranging from 0 to 10 volts?
What is the primary drawback of a weighted resistor DAC?
What is the primary drawback of a weighted resistor DAC?
What does the accuracy of a DAC depend on?
What does the accuracy of a DAC depend on?
What is defined as the smallest change that can occur in the magnitude of the analog signal in a DAC?
What is defined as the smallest change that can occur in the magnitude of the analog signal in a DAC?
What does resolution or step size as a percentage indicate in the context of a DAC?
What does resolution or step size as a percentage indicate in the context of a DAC?
In a basic DSP system, what is the role of the Digital to Analog Converter (DAC)?
In a basic DSP system, what is the role of the Digital to Analog Converter (DAC)?
What does the term full-scale output refer to in a DAC?
What does the term full-scale output refer to in a DAC?
What is the minimum sampling frequency required according to the Valvano Postulate to prevent aliasing?
What is the minimum sampling frequency required according to the Valvano Postulate to prevent aliasing?
How is the quantization step (q) generally calculated?
How is the quantization step (q) generally calculated?
What is one advantage of using a binary system over a decimal system for encoding?
What is one advantage of using a binary system over a decimal system for encoding?
What does the encoder do in the analog to digital conversion process?
What does the encoder do in the analog to digital conversion process?
Which of the following best describes the quantization error?
Which of the following best describes the quantization error?
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Study Notes
Digital to Analog Converter (DAC)
- Converts digital data (binary) to analog signal proportional to the decimal value of binary word.
- Output determined by voltage levels defined for binary 0 and 1.
Input-Output Relationship
- For a 3-bit converter:
- Generates 8 possible analog values (000 to 111) with corresponding output voltages from 0V to 7V/8.
- Step size calculated as ( N/2^n ) where N is the maximum voltage and n is the number of bits.
DAC Circuits
- Two-bit converter circuit uses two voltages V1 and V2 to produce output Vo, combining them to generate analog voltages.
- Three-bit converter adds V3 to achieve a wider output range through combinations of V1, V2, and V3.
Tinkercad Simulation
- Simulation settings may utilize voltage levels; for example, V can be set to 8 volts.
Color Codes for Circuits
- Red: Positive supply voltage1
- Green: Ground
- Pink: Positive supply voltage2
- Black: Negative supply voltage
- Blue: Input lines
- Purple: Output lines
- Yellow: Multimeter or CRO positive terminal
Operational Amplifiers (Op-Amps)
- Utilized in ADC configurations to achieve:
- High input impedance to prevent alteration of external components.
- Low output impedance to ensure consistent load.
- High gain (output/input), typically around 105.
- Configurations include open-loop (no feedback) and closed-loop (feedback in use).
ADC Converters
- Flash/Parallel ADC:
- Quick conversion use of multiple comparators, no clock required, faster but complex.
- Successive/Serial ADC:
- Utilizes a SAR register; slower with lower hardware demands, up to 16-bit resolution.
Serial Transmission
- Each bit is read sequentially in an analog-to-digital to serial format.
ADC Specifications
- Resolution defines smallest value analog signal can represent.
- Quantization error denotes the difference between actual and digitized values (+1 LSB).
- Conversion time is the duration taken to complete digitization.
- Accuracy influenced by underlying circuit errors.
Continuous vs. Discrete Conversion
- Continuous signal (analog) must be digitized to process in digital systems.
- Requires sensors to convert non-electrical signals to electrical signals.
Sampling and Quantization
- Sampling converts continuous signals to discrete using frequencies at least twice the maximum frequency (Nyquist theorem).
- Quantization sets discrete levels, with maximum quantization error being half the step size.
DAC Types
- Weighted Resistor DAC uses varying resistor weights based on bit importance.
- R-2R Ladder DAC utilizes two resistor values for efficient circuit design; lower error due to reduced tolerance issues.
Digital Signal Processing (DSP) Framework
- DSP systems consist of ADC, digital signal processor, filtering, and DAC, enabling effective signal manipulation.
Benefits of Binary Encoding
- Binary system requires fewer voltage levels (2) than decimal (10), reducing noise impact during transmission and simplifying electronic circuit design with Boolean algebra.
Summary of ADC Process
- Sampling: Converts continuous signals to discrete.
- Quantization: Discretizes amplitude values.
- Encoding: Produces binary output for further processing or transmission.
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