ee445:industrial electronics. outline introduction some application comparators integrators &...
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EE445:Industrial Electronics
Outline Introduction Some application
Comparators Integrators & Differentiators Summing Amplifier Digital-to-Analog (D/A) Converter Difference Amplifier Instrumentation Amplifiers Audio Amplifier
Operational Amplifier (Op-Amp)
Op-amp – A high-gain dc amplifier that has high input impedance and low output impedance.
The inverting (–) input and noninverting (+) input are signal inputs.
The +V and –V inputs are supply voltage inputs.
Differential Amplifier Differential amplifier – A circuit that amplifies
the difference between two input voltages. The op-amp signal inputs are connected to a
differential amplifier. The circuit amplifies the difference between the
voltages at its inverting () and noninverting (+) inputs.
Negative Feedback Negative feedback – A type of feedback in which
the feedback signal is 180° out of phase with the input signal.
Positive Feedback Positive feedback – A type of feedback in which the
feedback signal is in phase with the input signal.
Inverting Amplifier Operation The negative feedback path in the inverting
amplifier: Reduces voltage gain (from its open-loop value). Increases bandwidth (relative to its open-loop value).
Noninverting Amplifier Operation
The negative feedback path in the noninverting amplifier:
Reduces voltage gain (from its open-loop value). Increases bandwidth (relative to its open-loop value).
Comparators Comparator – A circuit used to compare two
voltages. Comparators are typically used in conjunction
with digital circuits. A digital circuit is one designed to respond to
alternating dc voltage levels.
Comparator Operation
Level Detector Level detector – Another name for a
comparator used to compare an input voltage to a fixed dc reference voltage.
Setting the Reference Level
21
2ref RR
RVV
Smoke Detector: A Comparator Application
Integrators Integrator – A circuit whose output is
proportional to the area of the input waveform.
RC Integrator An ideal RC integrator would produce the triangular
(ramp) waveform. The practical RC integrator produces the
exponential waveform.
Op-Amp Integrator The op-amp provides a constant-current
source for the capacitor, causing it to charge at a linear rate.
Differentiators Differentiator – A circuit whose output is
proportional to the rate of change of its input signal.
Summing Amplifiers Summing amplifier – An op-amp circuit that
produces an output proportional to the sum of its input voltages.
3
3
2
2
1
1out R
V
R
V
R
VRV f
General-Class Equation General-class equation – An equation derived for a
summing amplifier that is used to predict the circuit output for any combination of input voltages.
Determine the Rf / R ratio for each branch. Represent each branch as the product of its
resistance ratio and input voltage. Write the equation as the sum of these products.
Summing Amplifier Analysis
4321out
444
333
222
111
05.01.02.0
05.0
1.0
2.0
VVVVV
VVR
R
VVR
R
VVR
R
VVR
R
f
f
f
f
Digital-to-Analog (D/A) Converter
Digital-to-analog (D/A) converter – A circuit that converts digital circuit outputs to equivalent analog voltages.
4321out 125.025.05.0 VVVVV
Averaging Amplifier Averaging amplifier – A summing amplifier that
provides an output proportional to the average of the input voltages.
3321
out
VVVV
Difference Amplifier Difference amplifier – A summing amplifier
that provides an output proportional to the difference between two input voltages. Also called a subtractor.
)( 121
3out VV
R
RV
Instrumentation Amplifiers Instrumentation amplifier – A circuit used to
amplify low-level signals in process control and measurement applications.
GCL R
RA
21
Audio Amplifier Audio amplifier – The final audio stage in
communications receivers, used to drive the speakers.
Thank You
Any Q?