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Lab_26_class_A-B_PwrAmpcopy3

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					                Part 1a             Class-A Amplifier: DC Bias
Calculate the DC bias values for the circuit below.




                      Design Spec
VCC                                     10        Volt
Vi (peak)                               10        Volt
VO (RMS - Measured)                   2.804       Volt
R1                                     1000       Ω
R2                                     180        Ω
RE                                      20        Ω
RC                                     120        Ω
VBE                                     0.7       Volt
VB = R2 * VCC / R1 + R2               1.525       Volt
VE = VB - VBE                          0.83       Volt
IC ≈ IE = VE / RE                    0.04127      Amp
VRC = IC * RC                          4.95       Volt
VC = VO = VCC - VRC                   5.047       Volt


                Part 1b
Construct, measure and calculate IE based on measured values.
VB-meas                                1.48       Volt
VE-meas                               0.616       Volt
VC-meas                                6.34       Volt
IB (meas)                           0.000305      Amp
IC ≈ IE = VE / RE                    0.03080      Amp
               Part 2a




Calculate power and efficency values.
β = IC / IB                        100.984
Pi (dc) = VCC * IDC                   0.413       Watt
VO = VC-calculated                    5.047       Volt
                  2
PO (AC) =   (Vpeak    / 2) * RC       0.033       Watt
%η = 100 * (PO (AC) /Pi (DC))         7.938       %


               Part 2b

Using the oscilloscope adjust the input signal to obtain
an undistorted output signal, measure and record.
Vi-rms (meas)                         7.069        Volt
VC = VO-rms (meas)                    2.804       Volt
             Part 2c
Using the measured values calculate the power and efficency
Pi (DC) = VCC * IDC                  0.413     Watt
               2
PO (AC) = Vc-rms / RC                 0.066    Watt
%η = 100 * (PO (AC) /Pi (DC))        15.876    %

Compare the measured values of power and efficency obtained in Parts 2b and 2c.
Both have very low efficency ratings

            Part 2d
Reduce the input signal to 1/2 of part 2b
Measure and record
Vi-rms (meas)                           3.5    Volt
VC = VO-rms (meas)                     0.72    Volt
                Part 2e
Calculate input power and efficency values of the 1/2 input signal.
                         Design Spec
VCC                                      10      Volt
Vi (peak)                                5       Volt
VC = VO (RMS - Measured)                1.439    Volt
R1                                      1000     Ω
R2                                      180      Ω
RE                                       20      Ω
RC                                      120      Ω
VBE                                      0.7     Volt
VB = R2 * VCC / R1 + R2                 1.525    Volt
VE = VB - VBE                           0.83     Volt
IC ≈ IE = VE / RE                      0.04127   Amp
VRC = IC * RC                           4.95     Volt
VC = VO = VCC - VRC                     5.047    Volt


                Part 2f
Using the measured values calculate the power and efficency
Pi (DC) = VCC * IDC                  0.413     Watt
PO (AC) = Vc-rms2 / RC                  0.017    Watt
%η = 100 * (PO (AC) /Pi (DC))           4.181    %
                 Part 3a
Calculate the pwr ratings for a class-B amplifier




                            Design Spec
VCC                                         10       Volt
Vi (peak)                                    -       Volt
VC = VL = VO (peak)                         1        Volt
R1                                         1000      Ω
R2                                         1000      Ω
RE                                           -       Ω
RC                                           -       Ω
RL                                          10       Ω
VBE                                         0.7      Volt
IL = VO/RL                                  0.1      Amp
IDC = 2/π * IL-peak                       0.064      Amp
Pi-(dc) = VCC * IDC                       0.637      Watt
                   2
PO-(ac) =   VL-peak    / 2*RL             0.050      Watt
%η = (PO-(ac) / Pi-(dc)) * 100            7.853982   %
               Part 3b           VO = 1 volt
Using the measured values calculate the power and efficency
Vi-rms (meas)                        0.919     Volt
VC = VO-rms (meas)                  0.676      Volt
VC = VO-peak                          1        Volt
IL = VO/RL                           0.1       Amp
IDC = 2/π * IL-peak                 0.064      Amp
Pi (DC) = VCC * IDC                 0.637      Watt
                2
PO (AC) = Vc-rms / RL               0.046      Watt
%η = 100 * (PO (AC) /Pi (DC))       7.178      %



               Part 3c           VO = 2 volt
Using the measured values calculate the power and efficency
Vi-rms (meas)                        3.96      Volt
VC = VO-rms (meas)                  1.234      Volt
VC = VO-peak                          2        Volt
IDC (meas)                          0.045      Amp
Pi (DC) = VCC * IDC                 0.453      Watt
                2
PO (AC) = Vc-rms / RL               0.152      Watt
%η = 100 * (PO (AC) /Pi (DC))      33.615      %

				
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