Problem 7.7 - An Op-Amp Weighted Summing Circuit
*
* NOTE: This is a three-part problem.
* 1. Use V1 = 0 and V2 = .25*SIN(10ăt) as inputs to summing circuit.
* 2. Use V2 = 0 and V1 = .125*COS(10ăt) as inputs to summing circuit.
* 3. Let both sources be active and used as inputs to summing circuit.
* Use PROBE to display graphs of the input and output waveforms.
* Additional PROBE exercises are given in the problem statement.
*
* As a "PSpice experiment," edit the program for Part 3 to produce
* sinusoidal inputs of different frequencies. Use PROBE to display the
* result of adding these two signals. Observe that the sum of two
* sinusoids of different frequencies is NOT a sinusoidal waveform.
* This turns out to be an extremely important concept in steady-state
* ac circuit analysis, to be covered in later chapters of this course.
*
.OPT NOPAGE
V1 1 0 0
V2 2 0 sin(??????????????) ; Specify the sine wave parameters.
EAMP 4 0 ??? ??? 1E10 ; Enter the control voltage nodes.
R1 1 3 ??? ; Enter value for gain = -10.
R2 2 3 ??? ; Enter value for gain = -5.
R3 3 4 10K
RL 4 0 4.7K
.TRAN .02 1 0 .01 UIC ; Transient analysis period for five
; cycles of the 5 Hz input signal.
; The UIC statement suppresses the
; transient bias point calculation.
.PROBE
.END
Problem 7.7, Part 2. An Op-Amp Weighted Summing Circuit
*
* V2 = 0 and V1 = .125*COS(10ăt) as inputs to summing circuit.
*
.OPT NOPAGE NOBIAS
V1 1 0 sin(????????????????????????) ; Specify the parameters to
; describe a cosine wave with peak
; value = .125 and frequency = 5 Hz.
V2 2 0 0
EAMP 4 0 ??? ??? 1E10 ; Complete the amplifier description
R1 1 3 ??? ; as in Part 1.
R2 2 3 ???
R3 3 4 10K
RL 4 0 4.7K
.TRAN .02 1 0 .01
.PROBE
.END
Problem 7.7, Part 3. An Op-Amp Weighted Summing Circuit
*
* An op amp with two inputs and phase-inverted output.
* Gains calculated to be -10 for input V1 and -5 for input V2.
* V1=cosine function, V2=sine function at the same frequency.
*
.OPT NOPAGE NOBIAS
V1 1 0 sin(0 .125 ??????????????????) ; Complete the functions
V2 2 0 sin(0 .25 ??????) ; as above. Use PROBE
; to display the weighted sum of the
; different amplitude sinusoids.
EAMP 4 0 ??? ??? 1E10
R1 1 3 ???
R2 2 3 ???
R3 3 4 10K
RL 4 0 4.7K
.TRAN .02 1 0 .01
.PROBE
.END
* Problem 7.7, Part 4. An Op-Amp Weighted Summing Circuit
*
* Op amp with two inputs and phase-inverted output.
* Gains calculated to be -10 for input V1 and -5 for input V2.
* V1=cosine function at 5 Hz, V2=sine function at 3 Hz. Obtain a
* PROBE graph of the output waveform and the amplified individual
* input waveforms, as described in Part (d) of the problem in the
* PSpice manual. The output will not be a sinusoidal function.
*