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03 Handout 1

Eljin Aguilar Fundamentals of Mixed Signals and Sensors hard English 40 cards

03 Handout 1

Cards in this deck (40)

  1. 1SignalA voltage, current, or other quantity that conveys information
  2. 2Signalsare ultimately derived from the world outside the electronic system but may come from either real‐time
    information sources or information‐storage sources.
  3. 3Analog signalis a form of electrical energy (voltage, current, or electromagnetic power) where there is (ideally) a linear relationship between the electrical quantity and the value that the signal represents.
  4. 4Samplesdiscrete numbers that digital signals are invariably expressed at
  5. 5analog signalcan be represented mathematically as a continuous function of time v(t)
  6. 6sampling intervalsdiscrete times separated by
    intervals
  7. 7digital-to-analog (DACs or D/As) and analog-to-digital (ADCs or A/Ds)two basic types of converters
  8. 8DACoutputs an analog voltage that is a proportion of a reference voltage, the proportion based on the digital word applied.
  9. 9ADCa digital representation of the analog voltage, applied to its input, is outputted according to the reference voltage
  10. 10bitsThe digital input or output is arranged in words of varying widths that is called?
  11. 11bytesbits arranged in group of four
  12. 12A Digital-to-Analog converter [DA or DAC]is an electronic circuit that accepts a digital number at its input and produces a corresponding analog signal (usually a voltage) at the output.
    • When data is in binary form, the 0's and 1's may be of several forms where the logic zero may be a value up to 0.8 volts, and the 1s may be a voltage from 2 to 5 volts.
    • The data can be converted to clean digital form using gates designed to be on or off, depending on the value of the incoming signal.
  13. 13DAC Method – Shift KeyingThis method is used to send computer information over transmission channels that require analog signals. In each of these systems, an electromagnetic carrier wave is used to carry the information over distances. This basic process is given the name "shift-keying" to differentiate it from the purely analog systems.
  14. 14Amplitude Shift Keying• It is a technique in which the carrier signal is analog, and data to be modulated is digital. The amplitude of the analog carrier signal is modified to reflect binary data.
    • The binary signal, when modulated, gives a zero value when the binary data represents 0 while gives the carrier output when data is 1.
    • The frequency and phase of the carrier signal remain constant.
  15. 15Frequency Shift KeyingIn this modulation, the frequency of the analog carrier signal is modified to reflect binary data.
    • The output of a frequency shift keying modulated wave, is high in frequency for a binary high (‘1’) input, and is low in frequency for a binary low (‘0’) input.
    • The amplitude and phase of the carrier signal remain constant.
  16. 16Phase Shift Keying• In this modulation, the phase of the analog carrier signal is modified to reflect binary data.
    • The amplitude and frequency of the carrier signal remain constant.
  17. 17Kelvin Divider (String DAC)o Simplest voltage output DAC with a resistor string and a set of switches.
    o It uses the buffer, Op-Amp.
    o Number of resistances and switches: 2𝑁
    o The output impedance is code dependent in which if there are small code changes, it would have glitches (transient).
  18. 18𝑁 – number of bits 𝑉𝑂 – Voltage output 𝑉𝑅 – Reference voltage 𝑏𝑖 – Digital equivalent𝑁 –
    𝑉𝑂 –
    𝑉𝑅 –
    𝑏𝑖 –
  19. 19—Kelvin Divider (String DAC) formulaKelvin Divider (String DAC) formula
  20. 202^NFormula for number of resistors
  21. 21—Formula for number of 𝑆𝑤𝑖𝑡𝑐ℎ𝑒𝑠Formula for number of 𝑆𝑤𝑖𝑡𝑐ℎ𝑒𝑠
  22. 22Weighted Sum DACOne way to achieve D/A conversion is to use a
    summing amplifier.
    o This approach is not satisfactory for many bits
    because it requires too much precision in the
    summing resistors.
    o Inputs are weighted in the summing amplifier to
    produce the corresponding analog voltage
  23. 23—Weighted Sum DAC FormulaWeighted Sum DAC Formula
  24. 24𝑁 – number of bits 𝐼𝑂 – Current output 𝑉𝑂 – Voltage output 𝑉𝑅 – Reference voltage 𝑅𝑓 – Fixed Resistor 𝑅 – Junction Resistor 𝑏𝑖 – Digital equivalent𝑁 –
    𝐼𝑂 –
    𝑉𝑂 –
    𝑉𝑅 –
    𝑅𝑓 –
    𝑅 –
    𝑏𝑖 –
  25. 25—Weighted Sum DAC DiagramWeighted Sum DAC Diagram
  26. 26—Kelvin Divider (String DAC) DiagramKelvin Divider (String DAC) Diagram
  27. 27R-2R LadderThe summing amplifier with the R-2R ladder of resistances shown produces the output where the D's take the value 0 or 1.
    o The digital inputs could be TTL voltages which close the switches on a logical 1 and leave itgrounded for a logical 0.
    o It has two modes: Voltage mode & Current mode.
  28. 28—R-2R Ladder FormulaR-2R Ladder Formula
  29. 29—R-2R Ladder DiagramR-2R Ladder Diagram
  30. 30𝑉𝑂 – Voltage output 𝑉𝑅 – Reference voltage 𝑅𝑓 – Fixed Resistor 𝑅 – Junction Resistor 𝐷𝑛 – Digital equivalent (4 bits)𝑉𝑂 –
    𝑉𝑅 –
    𝑅𝑓 –
    𝑅 –
    𝐷𝑛 –
  31. 31Analog to Digital converter [AD or ADC]is an electronic circuit that accepts an analog input signal (usually a voltage) and produces a corresponding digital number at the output.
    • The basic principle of operation is to use the comparator principle to determine whether to turn on a bit of the binary number output.
    • Most ADC chips also include some of the support circuitry, such as a clock oscillator for the sampling clock, reference, the sample and hold function, and output data latches.    Analog to Digital converter [AD or ADC]
  32. 32Sampling• This is the technique that helps to collect the sample data at instantaneous values of the message signal, to reconstruct the original signal.
    • Pulse amplitude modulation is a technique in which the amplitude of each pulse is controlled by the instantaneous amplitude of the modulation signal.
  33. 33Quantizing• It is a process of reducing the excessive bits and confining the data.
    • The sampled output, when given to Quantizer, reduces the redundant bits and compresses the value.
  34. 34Encoder• The digitization of the analog signal is done by the encoder.
    • It designates each quantized level by a binary code.
    • The sampling done here is the sample-and-hold process.
    • A sample-and-hold circuit is usually used with an ADC to sample the input analog signal and hold the sampled signal.
  35. 35Successive-approximation ADC (SAR)o In this ADC, the normal counter is replaced with a successive approximation register.
    o This is designed to reduce the conversion and to increase the speed of operation.
    o The successive approximation registers count by changing the bits.
  36. 36—Successive-approximation ADC (SAR) DiagramSuccessive-approximation ADC (SAR) Diagram
  37. 37Flash ADCo It is a series of comparators in which each input compares to a unique reference voltage.
    o The comparator outputs connect to a priority encoder circuit, which produces a binary output.
    o As the analog input voltage exceeds the reference voltage at each comparator, the comparator outputs will sequentially saturate to a high state.
    o The priority encoder generates a binary number based on the highest-order active input, ignoring all
    other active inputs.
  38. 38—Flash ADC DiagramFlash ADC Diagram
  39. 39Single-Slope Integrating ADCo An unknown input voltage is integrated, and the value is compared against a known reference value.
    o The time it takes for the integrator to trip the comparator is proportional to the unknown voltage.
    o In this case, the known reference voltage must be stable and accurate to guarantee the accuracy of the
    measurement.
  40. 40—Single-Slope Integrating ADC DiagramSingle-Slope Integrating ADC Diagram

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hard Fundamentals of Mixed Signals and Sensors Flashcards on 03 Handout 1, created by Eljin Aguilar on 20/09/2024.
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