EEE 432
Measurement and Instrumentation
Lecture 7
Analog Signal processing
Prof. Dr. Murat Aşkar
İzmir University of Economics
Dept. of Electrical and Electronics Engineering
Signal processing
 Signal processing is concerned with improving the quality of
the reading or signal at the output of a measurement system,
and one particular aim is to attenuate any noise in the
measurement signal that has not been eliminated by careful
design of the measurement system
 Analog signal processing
 Digital signal processing
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1
Signal processing
Analog Signal Processing
 Filters
 Signal Differentiation
– Passive
 Voltage follower (pre-amplifier)
– Active
 Voltage comparator
 Signal amplification
 Voltage-to-current converter
 Signal attenuation
 Current to-voltage converter
 Differential amplification
 Phase-sensitive detector
 Signal linearization
 Lock-in amplifier
 Bias (zero drift) removal
 Signal addition
 Signal Integration
 Signal multiplication
3
Signal processing
Digital signal processing
 Sample and hold circuit
 Analog-to-digital (A/D) conversion
 Digital-to-analog (D/A) conversion
 Digital filtering
 Autocorrelation
 Other digital signal processing operations
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2
Signal processing
Filters
Filter : a circuit that is designed to pass signals with
desired frequencies and reject or attenuate others
4 types of filters:
1. Low-pass filter: passes low frequencies and stops high
frequencies
2. High-pass filter: passes high frequencies and rejects
low frequencies
3. Band-pass filter: passes frequencies within a frequency
band and blocks or attenuates frequencies outside the
band
4. Band-reject filter: passes frequencies outside a
frequency band and blocks or attenuates frequencies
within the band
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Filters
Low Pass Filter
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3
Filters
High Pass Filter
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Filters
Band Pass Filter
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4
Filters
Band Reject Filter
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Filters
Passive Filters
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5
Filters
Active Filters
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Analog Signal Processing
Signal Amplification
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6
Analog Signal Processing
Signal Attenuation
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Analog Signal Processing
Differential Amplification
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7
Analog Signal Processing
Signal Linearization
Light intensity transducers typically have an exponential
relationship between the output signal and the input light
intensity, i.e.: VI = Ke-aQ
where Q is the light intensity, VI is the voltage level of the
output signal, and K and a are constants.
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Analog Signal Processing
Bias Removal
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8
Analog Signal Processing
Signal Integration
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Analog Signal Processing
Signal Differentiation
dVin Vout

0
dt
R
dV
Vout   RC in
dt
C
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9
Analog Signal Processing
Voltage Comparator
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Analog Signal Processing
Voltage-to-Current Converter
I 
R2
Vin
R1 R3
R1 R3  R5   R2 R4
Rml 


 Im
R3  R4  R5

R4  R5  Vsat  R3 
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10
Analog Signal Processing
Current-to-Voltage Converter
Vout   IR
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Signal processing
Analog Signal Processing
 Filters
 Signal Differentiation
– Passive
 Voltage follower (pre-amplifier)
– Active
 Voltage comparator
 Signal amplification
 Voltage-to-current converter
 Signal attenuation
 Current to-voltage converter
 Differential amplification
 Phase-sensitive detector
 Signal linearization
 Lock-in amplifier
 Bias (zero drift) removal
 Signal addition
 Signal Integration
 Signal multiplication
22
11
Signal processing
Digital signal processing
 Sample and hold circuit
 Analog-to-digital (A/D) conversion
 Digital-to-analog (D/A) conversion
 Digital filtering
 Autocorrelation
 Other digital signal processing operations
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12