ECE 03 - Electronics System & Design Quiz

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Questions and Answers

What happens when VAX exceeds VA by at least an amount equal to the threshold voltage VT?

The comparator output goes HIGH.

The register number continues to modify.

The process of conversion stops. (correct)

The DAC output resets to zero.

What is the role of the control logic in the digital-ramp ADC?

To initiate the conversion process.

To increment the DAC output.

To reset the counter.

To activate the end of conversion signal, EOC. (correct)

Which component is NOT part of the digital-ramp ADC?

Registers (correct)

Comparator

Control AND gate

Counter

During the conversion process, when does the counter stop counting?

When VAX exceeds VA by more than VT. Signup and view all the answers

What signal will the comparator output indicate when VA is greater than VAX during initialization?

HIGH Signup and view all the answers

How does the clock influence the digital-ramp ADC?

It determines the speed of the conversion. Signup and view all the answers

What is the typical range of the threshold voltage VT in a digital-ramp ADC?

10 to 100 μV Signup and view all the answers

What does the counter hold at the end of the conversion process?

The digital representation of VA. Signup and view all the answers

What is the output current Io for a digital input of 11101 if K is found to be 0.5 mA?

14.5 mA Signup and view all the answers

What is the largest output voltage from an 8-bit DAC that produces 1.0V for a digital input of 00110010?

5.1 V Signup and view all the answers

What does an analog to digital converter (ADC) primarily do?

Takes analog input and produces a digital output code Signup and view all the answers

What is the first step in the operation of an analog to digital converter?

The start command pulse initiates the operation Signup and view all the answers

In the DAC equation Vo = K × digital input, what does the variable K represent?

Output current per digital input level Signup and view all the answers

During the A/D conversion process, what role does the comparator play?

It compares VAX with the analog input VA Signup and view all the answers

If the binary input to a 5-bit DAC is 10100, what is the decimal equivalent of the input?

20 Signup and view all the answers

What is the maximum binary input for an 8-bit DAC?

255 Signup and view all the answers

What is the digital equivalent of an analog voltage of 3.728 V in a 10-bit DAC?

373 Signup and view all the answers

How is the step size of the DAC calculated?

Total output voltage divided by the number of steps Signup and view all the answers

What is the formula for calculating the conversion time of an ADC?

Number of steps divided by clock frequency Signup and view all the answers

What is a primary advantage of using operational amplifiers in circuit design?

Low programming overhead Signup and view all the answers

Which disadvantage is associated with analog inputs and outputs in microcontroller applications?

They complicate circuit design with the need for external ADC or DAC Signup and view all the answers

What is the resolution of the DAC expressed as a percentage?

0.1% Signup and view all the answers

What does a ladder network convert?

Digital input values into analog voltage levels Signup and view all the answers

Which components are part of a successive approximation ADC?

Successive approximation register and DAC Signup and view all the answers

How does the successive approximation register function in an ADC?

Counts bits starting from the most significant to the least Signup and view all the answers

If a ladder network has 10 stages, what will be the voltage resolution based on a reference voltage of $V_{ref} = 10 V$?

$10/1024$ Signup and view all the answers

What does the constant K represent in the relationship between analog output and digital input?

The proportionality factor with a constant value Signup and view all the answers

What is the main purpose of the comparator in a successive approximation ADC?

To compare the DAC output with the analog input Signup and view all the answers

What is the purpose of the Result register in a successive approximation ADC?

To store the final digital output equivalent Signup and view all the answers

How many unique voltage levels can a 4-bit ladder network generate?

16 levels Signup and view all the answers

What happens to the frequency response of programmable operational amplifiers when the bias current is increased?

The frequency response improves Signup and view all the answers

What is a drawback of operational amplifiers when considering higher resolutions?

They have high costs associated with higher resolutions Signup and view all the answers

What is the primary purpose of an interface circuit in electronics?

To condition signals from sensors for compatibility with load devices Signup and view all the answers

Which type of device is a transducer?

A device that converts physical variables into electrical variables Signup and view all the answers

What role does the Analog to Digital Converter (ADC) play in an electronic system?

It converts analog input signals into digital output signals Signup and view all the answers

How does a Digital to Analog Converter (DAC) function in a system?

It converts digital output from a computer back into an analog signal Signup and view all the answers

What is a common characteristic of signals produced by most passive sensors?

They often produce weak output signals Signup and view all the answers

What is the main function of actuators in an electronic control system?

To convert signals into mechanical energy Signup and view all the answers

In a microcontroller system, what is the typical flow of data?

Read inputs, perform processing, and write to outputs Signup and view all the answers

When interfacing sensors, what is often necessary for handling weak output signals?

Amplification to enhance signal strength Signup and view all the answers

Study Notes

ECE 03 - Electronics 3: Electronics System & Design

Course offered by Engr. Joel Anthony L. Sevilla in December 2024, for BSECE III students.

Interfacing Techniques

An interface circuit conditions a signal from a sensor to a compatible format for the load device.

ADC and DAC Interface

A system diagram shows a physical variable (input), transducer, ADC, digital system, DAC, actuator, and output of a physical variable (output).
The transducer changes the physical variable to an electrical signal (analog current or voltage).
The ADC converts the analog signal to digital data.
The digital system processes the digital data.
The DAC converts the digital data back to an analog signal.
The actuator uses the analog signal to control the output physical variable.

Transducer

A transducer converts a physical variable into an electrical variable.
Examples include thermistors, photocells, photodiodes, flow meters, pressure transducers, and tachometers.
The transducer's output is proportional to the physical variable.

Analog to Digital Converter (ADC)

The electrical analog output from the sensor is the analog input for the ADC.
The ADC converts this signal to a digital output.
The digital output uses bits representing the analog input's value.

Digital System

The digital computer receives digital data from the ADC.
The computer interprets data based on a running program.
This might involve calculations or other operations.

Digital to Analog Converter (DAC)

The digital output from the computer is an input to the DAC.
The DAC converts the digital data to an analog voltage or current.

Actuator

The output from the DAC controls another device or circuit.
Actuators cause operation of machines or other devices.

Amplifiers

Passive sensors output weak signals (microvolts or picoamperes).
Amplifiers increase the signal.
These will have voltage gains of up to 10,000, and current gains of up to 1 million.
Operational amplifiers are common building blocks for such amplifiers.

Operational Amplifiers

Op-amps and discrete components (resistors, capacitors, inductors) are used.
Numerous circuits are possible (e.g., amplifiers, summers, integrators, differentiators).
Programmable operational amplifiers allow users to control bias current and frequency response.

Analog Inputs/Outputs

Analog input output is voltage-based control and monitoring.
Advantages include simple interface, low cost for low-resolution applications, high speed, and low programming overhead.
Disadvantages include high cost for larger resolutions, not all microcontrollers have built-in, and external components complicate circuit design.

Digital to Analog Conversion (Ladder Network)

A ladder network converts binary inputs (0V or Vref) into a voltage output proportional to the input value.
A ladder network with four input voltages (4 bits) and a DC voltage output is shown.
The output voltage is proportional to the digital input value.
The formula for output voltage is provided.
The number of voltage levels and steps can be increased with more ladder sections.

Example problems and solutions on DAC calculations.

Problems including the calculation of proportionality constant K and analog output voltage Lo are presented, along with solutions.
For example, given a DAC, the digital inputs, and output voltage, calculate the other variables.

Analog to Digital Converter (ADC) types

This section mentions different types of Analog-to-Digital Converters (ADCs):
- Flash ADC
- Successive Approximation
- Dual-Slope Integration
- Delta-Sigma

Successive Approximation ADC

These ADCs are popular due to low cost and ease of interfacing with microcontrollers.
A successive approximation ADC consists of four main components:
- Successive approximation register
- Result register
- DAC
- Comparator

Digital-Ramp ADC

A simple type of ADC consisting of a counter, a DAC, a comparator, and an AND gate.
The steps involved in the operation are detailed, including the effect of the START pulse, the output voltage from the DAC as the counter advances and, the comparator's response in relation to VA and VT.
Specific example of digital-ramp ADC calculation is provided.

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Description

Test your knowledge on interfacing techniques, ADC and DAC systems, and transducers in electronics. This quiz is designed specifically for BSECE III students. Get ready to explore the fundamentals of electronics design and signal processing.