Next: Digital Circuits
Up: Operational Amplifiers
Previous: Current Limiting and Slew

Consider the circuit below. (You may assume that the opamps are
ideal.)
 Write an expression for the transfer function .
Express your result in terms of the amplitude of the output and
the phase relative to the input. Let k ,
, F and F. Do
not simplify the algebra.
 What are the (real) zeroes in the transfer function, if any?
 What are the (real) poles in the transfer function if any?
 Sketch the transfer function as a function of on a
loglog plot. Your sketch should show the slope of in the large and small limits, the corner
frequencies, and the value of at the corner
frequencies.
 Describe the dependence of the output on frequency at small and
large frequencies in dB/octave.

 Write the two rules for the analysis of circuits which utilize
``ideal'' opamps.
 Write an expression for the potential for the
following circuit.
 Let k and k . Sketch a loglog
plot showing the function for the above
circuit assuming that a general purpose opamp such as the 741
is used.
 The 741 opamp has a corner frequencies of 4 Hz, DC openloop
gain of and a fall off at high frequency of
6 dB/octave. What is the frequency domain over which the
amplifier defined in part (c) will have constant gain? What is
the gain of the amplifier in this frequency domain?
 Suppose now that the impedance is replaced with a
capacitor with a capacitance C ( k ). For
frequencies much greater than 4 Hz, the 741 opamp will
attenuate the signal if the product RC is greater than some
maximum value. For a frequency of 50 kHz, what is the maximum
value for C for which the opamp will not
attenuate the output signal at high frequencies? Hint: If
you sketch and , you will be
able to see the constraint on .

Set up an operational amplifier circuit to solve the equation
Hint: the input is .

Draw a schematic diagram of a circuit for which .
Specify the limitations on the input voltage range, if any.
Next: Digital Circuits
Up: Operational Amplifiers
Previous: Current Limiting and Slew
Doug Gingrich
Tue Jul 13 16:55:15 EDT 1999