EE 42 Homework and Reading No. 5
Homework assigned Thursday 24 Feb. 2005; due at 5:30 pm Thursday 3 March 2005 in the box labeled EE 42 in Room 240 Cory Hall. Note: your graded homeworks will be returned in your discussion section; your GSI will keep your homework until you pick it up to maintain privacy.
Reading: Hambley: Op-Amps. Secs. 14.1-14.3; 14.9
Problems are all in Hambley, 3 rd
Ed. (10 points each except where noted):
1.
P14.8 (inverting amp with an ac input signal) Note: This is NOT a phasor problem.
2.
P14.17 (20 points). (some ideal op-amp circuits) Note that the text defines on p.
635 its term “summing-point constraint” to mean that for ideal op-amps no current enters either input terminal and the voltage between the two input terminals is zero.
3.
P14.22 (power gain with op-amps) Note: The power gain of an amplifier is the ratio of the output power delivered to the load (R
L
in this problem) to the input power delivered by the source. (Hint: How much power does the source deliver to the input of circuit b?)
4.
P14.24. (shows how using actual resistors that have some manufacturing tolerances in their values will affect the gain of an op-amp amplifier)
5.
P14.64 (op-amp differentiator)
6.
P14.67 (20 points) (using an op-amp to make an integrator)
Note 1: This circuit (if we ignore the switch) is like the op-amp differentiator except that the positions of the resistor and capacitor have been reversed. The switch was there so that the integrator could be reset (in Problem 14.63) where it was integrating digital pulses from the source.
Note 2: As a reminder, a magnitude Bode plot of the output amplitude from a filter is a log-log plot of output voltage versus frequency. You know about decibels now, so you should plot the magnitude of the output v
0
in decibels ( =
20 log
10
(v
0
/ v reference
), where v reference
can be 1 volt) versus the frequency on a log scale. (For example, equal distances between 10 Hz and 100 Hz, between 100 Hz and 1000 Hz, etc)
Note 3: Your text shows a magnitude Bode plot as Fig. 6.15 on page 275.
Note 4: Given the nature of logarithms, a ratio in decibels of v
0
/ v reference less than
1 will be a negative number.