Analog Assignment Finalprint

download Analog Assignment Finalprint

of 20

Transcript of Analog Assignment Finalprint

  • 8/17/2019 Analog Assignment Finalprint

    1/20

     

    A REPORT ON

    ANALOG ASSIGNMENT ON TEXASINSTRUMENTATION KIT

     In partial fulfillment of the course:

     Analog Electronics EEE F 341  

    Submitted by:

    NITISH MITTAL 2011B3A3373P

    HRISHIKESH MUKTE 2011B3A3385P

    NANDURI PRABHAKAR

    NARASIMHA

    2011B1A3742P

    Lab Instructors: Priya Gupta,Jitendra

    Lab Section No: 2

    Assignment Question:

    Group No: 1

    Assignment 2 - Group A

    Instructor-in-Charge: Prof. V.K.CHAUBEY 

    BIRLA INSTITUTE OF TECHNOLOGY & SCIENCE, PILANI

    RAJASTHAN, 333031APRIL, 2015

  • 8/17/2019 Analog Assignment Finalprint

    2/20

    EXPERIMENT NO. 1: SECOND ORDER MFB BANDPASS FILTER

    AIM 

    Design a second order MFB Band pass filter with a mid frequency of Fm = 1 KHz, a Quality

    factor of Q=1, and a Gain of -2.

    CIRCUIT DIAGRAM

    To Implement the second order MFB Band pass filter the following circuit design was used.

    Fig. 1 - Circuit Diagram for second order MFB Band pass filter

    PRINCIPLE 

    The multiple feedback filters use one op-amp for a two-pole section, injecting signal into the

    inverting input of the op-amp, usually with the non-inverting input grounded. This limits the

    swing of the common mode input voltage and provides better distortion for larger signal

    swings. Gain depends on resistor ratios, so pass-band gain is dependent on the accuracy of

    the resistors chosen. It is not possible to build multiple feedback filters with zeros. Multiple

    feedback topologies are generally preferred because of better sensitivity to component

    variations and better high-frequency behavior and are used in filters to have high quality

    factor and require high gain.

    TRANSFER FUNCTION:-

  • 8/17/2019 Analog Assignment Finalprint

    3/20

    MATHEMATICAL FORMULAE: 

    OBSERVATIONS & CALCULATIONS 

    Theoretical values of R 2  and R 1 are calculated as 3.2k Ω and 795.77Ω, and C=0.1uF. R 3  is

    calculated as an infinitely large value and thus open circuit.

    In TI kit for R 1 3.2k (series of 2.2k and 1k) and 1k are put in parallel. For R 2 2.2k and 1k are

     put in series.

    Frequency(in KHz) Vin(in mV) Vout (in mV) Gain(V/V)

    0.08 100 16 0.160.213 100 41.8 0.418

    0.305 100 65.6 0.656

    0.404 100 80 0.8

    0.495 100 102 1.02

    0.592 100 126 1.26

    0.708 100 151 1.51

    0.81 100 179 1.79

    0.915 100 195 1.95

    1.031 100 202 2.02

    1.13 100 204 2.04

    1.201 100 208 2.08

    1.307 100 193 1.93

    1.411 100 184 1.84

    1.5 100 176 1.76

    1.628 100 161 1.61

    1.747 100 150 1.5

    1.908 100 132 1.32

    2.117 100 115 1.15

    2.341 100 103 1.03

    2.52 100 94 0.94

  • 8/17/2019 Analog Assignment Finalprint

    4/20

    2.6 100 90.5 0.905

    2.714 100 87.6 0.876

    3 100 76.7 0.767

    3.214 100 72.9 0.729

    3.528 100 64.5 0.645

    3.7 100 60.4 0.604

    4.2 100 53.7 0.537

    4.524 100 51.2 0.512

    5.153 100 43.8 0.438

    6.192 100 36.7 0.367

    6.571 100 33.9 0.339

    6.98 100 32 0.32

    7.55 100 29.9 0.299

    9.122 100 24 0.24

    10.2 100 21.2 0.21220 100 11.3 0.113

    Gain at Fm = -2.02

    Lower cut off frequency = 670 Hz.

    Upper cut off frequency = 1.8 kHz

    Observed Bandwidth = 1.130 kHz.

    Theoretical bandwidth = 994.7 Hz

  • 8/17/2019 Analog Assignment Finalprint

    5/20

    TI CIRCUITRY

    WAVEFORMS

    The phase response and bode plot of the transfer function can be seen below.

  • 8/17/2019 Analog Assignment Finalprint

    6/20

    Ideal Wave Forms

  • 8/17/2019 Analog Assignment Finalprint

    7/20

    WAVEFORMS FROM DSO

    Various waveforms of input output were observed on DSO

  • 8/17/2019 Analog Assignment Finalprint

    8/20

     

  • 8/17/2019 Analog Assignment Finalprint

    9/20

     

    CONCLUSION 

    After conducting the experiment, the gain and center frequency of for second order MFB

    Band pass filter are found to be almost equal to their theoretical values. Gain for the passstage was around -2 and the center frequency came out to be 1 kHz. The bandwidth was

    found to be 1.130 kHz, in close proximity to the theoretical value of 0.994 kHz.

  • 8/17/2019 Analog Assignment Finalprint

    10/20

    EXPERIMENT NO. 2: 4-bit R-2R ladder DAC using op-amp 

    AIM

    Design a 4-bit R-2R ladder DAC using op-amp. Measure the analog output voltage for digital

    input word. Calculate maximum linearity error and accuracy.

    CIRCUIT DIAGRAM

    Fig. 4 - Circuit Diagram for a 4-bit R-2R ladder DAC using op-amp.

    PRINCIPLE

    The circuit uses only two resistor values. Each switch has its own binary bit of the digital

    input word, which controls it. The switch is connected to Vr when the binary bit is 1 and

    connected to ground when the binary bit is 0.

    The Thevenin of the circuit is computed. The Thevenin on both sides of the circuit gives the

    current flowing in the opamp and thus the opamp output voltage can be computed.

  • 8/17/2019 Analog Assignment Finalprint

    11/20

     

    Accuracy is a comparison of the actual output of a DAC with the expected output. It is

    expressed as a percentage of a full-scale, or maximum, output voltage. Accuracy is a measure

    of what voltage is expected at the output vs. what actually appears.

    A linear error is a deviation from the ideal straight-line output of a DAC. A special case is an

    offset error, which is the amount of output voltage when the input bits are all zeros.

      Advantages

     –   Only two resistor values

     –   Does not need as precision resistors as Binary weighted DACs

     –   Cheap and Easy to manufacture

      Disadvantages

     –   Slower conversion rate

    The values will be observed using a multimeter.

    MATHEMATICAL FORMULAE:

    From the circuit, the output voltage is:

  • 8/17/2019 Analog Assignment Finalprint

    12/20

    OBSERVATIONS & CALCULATIONS:

    Choosing the value of Vref = 5V, R = 1 k Ω, 2R = 2.2 k Ω, Rf = 2.2 k Ω.

    Decimal Binary

    Word

    Voutput(in

    Volts)(observed)

    Voutput  (in

    Volts)(theoretical)  

    Accuracy (in %)

    (Vexpected-Vactual)/Vexpected*100

    Linearity (Deviation)

    Vobs-Vtheory

    0 0000 0 0 0

    1 0001 -0.6958 -0.625 -11.328 -0.0708

    2 0010 -1.3308 -1.25 -6.464 -0.0808

    3 0011 -2.001 -1.875 -6.72 -0.126

    4 0100 -2.53 -2.5 -1.2 -0.03

    5 0101 -3.2 -3.125 -2.4 -0.075

    6 0110 -3.841 -3.75 -2.427 -0.091

    7 0111 -4.524 -4.375 -3.4057 -0.149

    8 1000 -4.864 -5 2.72 0.1369 1001 -5.54 -5.625 1.511 0.085

    10 1010 -6.175 -6.25 1.2 0.075

    11 1011 -6.857 -6.875 0.262 0.018

    12 1100 -7.384 -7.5 1.547 0.116

    13 1101 -8.063 -8.125 0.763 0.062

    14 1110 -8.637 -8.75 1.29 0.113

    15 1111 -8.684 -9.375 7.371 0.691

    V0= -2.2k[b3/2.2k + b2/4.4k + b3/8.8k + b0/19.6k]* Vref  

      V0= 5[b3 + b2/2 + b1/4 + b0/8]

    Analog Output Voltage vs. Digital Input Graph

    -10

    -9

    -8

    -7

    -6

    -5

    -4

    -3

    -2

    -1

    0

            0 1        1        0

            1        1

            1        0        0

            1        0        1

            1        1        0

            1        1        1

            1        0        0        0

            1        0        0        1

            1        0        1        0

            1        0        1        1

            1        1        0        0

            1        1        0        1

            1        1        1        0

            1        1        1        1

    Vout Analog vs Digital Word

    Voutputanalog(observed)

    Vout(Theoretical)

  • 8/17/2019 Analog Assignment Finalprint

    13/20

     

    Linearity vs. digital output

    Accuracy vs. digital output

    CONCLUSION

    Thus, the R-2R ladder can be used to obtain binary weighted voltages or currents using only a

    single-sized resistor (the resistors of size 2R can be made of two resistors of size R, to

    improve matching properties.) As a result, this R-2R approach gives better accuracy. Further,

    the resistors can be lower in value, giving high speed operation.

    -0.2

    -0.1

    0

    0.1

    0.2

    0.3

    0.4

    0.50.6

    0.7

    0.8

            0 1        1        0

            1        1

            1        0        0

            1        0        1

            1        1        0

            1        1        1

            1        0        0        0

            1        0        0        1

            1        0        1        0

            1        0        1        1

            1        1        0        0

            1        1        0        1

            1        1        1        0

            1        1        1        1

    Linearity

    Linearity

    -15

    -10

    -5

    0

    5

    10

            1        1        0

            1        1

            1        0        0

            1        0        1

            1        1        0

            1        1        1

            1        0        0        0

            1        0        0        1

            1        0        1        0

            1        0        1        1

            1        1        0        0

            1        1        0        1

            1        1        1        0

            1        1        1        1

    Accuracy

    Accuracy

  • 8/17/2019 Analog Assignment Finalprint

    14/20

    EXPERIMENT NO. 3:Aastable multivibrator (Triangular wave generator) 

    AIM 

    Design an astable multivibrator (Triangular wave generator), for a frequency of 1 KHz.

    CIRCUIT DIAGRAM

    The Circuit Diagram for an astable multivibrator (Triangular wave generator), used for

    framing the circuit during the experimentation phase is shown below.

    Circuit Diagram of an astable multivibrator (Triangular wave generator)

    PRINCIPLE

    The astable multivibrator has no stable states. Let us assume that the output is at +Vsat at the

    instant of switching on the power supplies. The capacitor C will start charging towards +Vsat

    through R and the voltage across the capacitor which is also the input to the inverting

    terminal will start rising exponentially towards +Vsat with a time constant RC. The momentthe capacitor voltage reaches Vut, the inverting input voltage will exceed the non-inverting

    terminal voltage and the output Vo will be switched to  – Vsat. The capacitor will start

    discharging and its voltage will decrease exponentially towards  – Vsat. This new state will

    continue till Vlt. At this instant, the output will again be switched back to +Vsat and the cycle

    will repeat. There are two quasi-stable states and the circuit oscillates between +Vsat and -

    Vsat producing a square waveform at the output. The time period is determined by the time

    constant of the RC network and the value of the threshold voltages.

    The simplest method of forming a triangular waveform generator is to integrate the square

    waveform. Thus, by connecting an integrator to a square waveform generator, a triangularwaveform can be generated.

  • 8/17/2019 Analog Assignment Finalprint

    15/20

    The frequency of the square and the triangular waveforms are identical. R3C1 is chosen equal

    to T and R4 resistor shunts the capacitor to obtain a stable triangular waveform.

    MATHEMATICAL FORMULAE 

    Frequency of triangular waveform, is given as:

    F =2

    41

     

    CALCULATIONS

    Calculating we get theoretical values of R 2 = 4k, R=10k and R 1=1k and C=0.1F. These values

    give a frequency of 1k Hz theoretically. Or using a capacitance of 1uF gives R 2=4k, R=10k

    and R 1=100 ohms.

    So adjusting these values in the TI kit the desired frequency of 1k is obtained using R 2=3k,

    R=10k and R 1=1k. The capacitance is kept at 1uF. R 3 and R 4 = 1k to keep gain as unity. The

    appropriate triangular waveform cannot be obtained at C= 0.1uF.

    R1 = 1k R2 = 3k R = 10k

    R3 = 1k R4 = 1k

    C = 1uF 

    TI KIT CIRCUITRY

  • 8/17/2019 Analog Assignment Finalprint

    16/20

    WAVEFORMS

    Square waveform obtained at output of 1st amplifier (F=1.020Hz)

    The square waveform showing Max and Min and Peak to Peak values.

  • 8/17/2019 Analog Assignment Finalprint

    17/20

    Required Triangular Waveform Obtained at Output with required frequency (f=1.020Hz)

    Triangular Waveform - max, min and peak to peak values.

    Amplitude of output waveform = 3.64V (pk to pk)

    CONCLUSION 

    A simple astable multivibrator was designed with certain values of R and C and triangularwaveform observed.

  • 8/17/2019 Analog Assignment Finalprint

    18/20

    READINGS FOR THE EXPERIMENTS (Verified by the lab assistants)

    Readings for the second order MFB band Pass Filter

  • 8/17/2019 Analog Assignment Finalprint

    19/20

     

    Readings for 4 bits R-2R ladder DAC using op-amp

    Readings for Astable Multivibrator (triangular wave generator

  • 8/17/2019 Analog Assignment Finalprint

    20/20

    References

    1)   Laboratory Experiments and PSPICE Simulations in Analog Electronics, Maheshwari

     L.K., Anand M.M.S., Prentice Hall of India, 2006

    2)   Analog Electronics, LK Maheshwari and MMS Anand, PHL Learning Private Limited

     Delhi, 2013