Lecture 14
31
October 19, 2007 1 EE 359 Electronic Circuits Filters and Tuned Filters and Tuned Amplifiers Amplifiers Second order LCR resonator Second order Active Filters based on Inductor Replacement Signal Generators Signal Generators Oscillators
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Transcript of Lecture 14
October 19, 20071
EE 359 Electronic Circuits
Filters and Tuned AmplifiersFilters and Tuned Amplifiers
Second order LCR resonator
Second order Active Filters based on Inductor Replacement
Signal GeneratorsSignal GeneratorsOscillators
October 19, 20072
EE 359 Electronic Circuits
HW
Due today 12.7, 12.9,12.28, 12.34
Review October 26
Quiz#2 October 29
October 19, 20073
EE 359 Electronic Circuits
Second Order LCR Resonator
• LCR Resonator
• Excite parallel LCR resonator– Determine natural
modes (I.e. poles of response function)
LCCRss
CsRsCsLYI
V
/1)/1(
/
/1/1
11
2
0
CRQ
LC
CRQ
LC
0
0
0
20
/1
/1/
/1
October 19, 20074
EE 359 Electronic Circuits
Transmission Zeros LPF
• Where to inject iput signal Vi ?
• Transmission zeros are when Z2(s) are zero (if Z1
)()(
)(
)(
)()(
21
20
sZsZ
sZ
sV
sVsT
i
October 19, 20075
EE 359 Electronic Circuits
Realization of Low Pass Function
• Transmission zeros are when series impedance becomes infinite.
0/1
1
RsCssL
RsCsL
sL
YY
Y
ZZ
Z
V
VsT
i /1/1
/1)(
21
1
21
20
October 19, 20076
EE 359 Electronic Circuits
High Pass Filter
• Use the series capacitor. Transmission zero at s=0 (dc), shunt inductor is a tranmission zero at s=0.
200
2
220
/)(
Qss
sa
V
VsT
i
October 19, 20077
EE 359 Electronic Circuits
Bandpass Filter
• Zero at s=0 due to shunt inductor, s=infinity due to shunt capacitor.
LCCRss
CRs
V
VsT
i /1/1
)/1()(
20
October 19, 20078
EE 359 Electronic Circuits
Inductance Simulation
• Use opamps instead of inductor!
October 19, 20079
EE 359 Electronic Circuits
Low Pass Filter
)()(
)(
)(
)()(
21
20
sZsZ
sZ
sV
sVsT
i
RsCsL
sL
YY
Y
ZZ
Z
V
VsT
i /1/1
/1)(
21
1
21
20
October 19, 200710
EE 359 Electronic Circuits
High Pass Filter
• 200
2
220
/)(
Qss
sa
V
VsT
i
October 19, 200711
EE 359 Electronic Circuits
Bandpass Filter
•
LCCRss
CRs
V
VsT
i /1/1
)/1()(
20
October 19, 200712
EE 359 Electronic Circuits
Low Pass Notch filter
•
October 19, 200713
EE 359 Electronic Circuits
Second-order narrow-band bandpass filter by transforming a first-order low-pass filter. (a) Pole of the first-order filter in the s-plane. (b) Applying the transformation s = p + j0
and adding a complex conjugate pole results in the poles of the second-order bandpass filter. (c) Magnitude response of the firs-order low-pass filter. (d) Magnitude response of the second-order bandpass filter.
Second-order narrow-band bandpass filter by transforming a first-order low-pass filter
October 19, 200714
EE 359 Electronic Circuits
Poles and the frequency response of a fourth-order stagger-tuned narrow-band bandpass amplifier by transforming a second-order low-pass .
October 19, 200715
EE 359 Electronic Circuits
SIGNAL GENERATORS /OSCILLATORS
A positive-feedback loop is formed by an amplifier and a frequency-selective network
In an actual oscillator circuit, no input signal will be present
October 19, 200716
EE 359 Electronic Circuits
Oscillator-frequency stability
October 19, 200717
EE 359 Electronic Circuits
Limiter Ckt Comparator
October 19, 200718
EE 359 Electronic Circuits
Wien-bridge oscillator
without amplitude stabilization.
October 19, 200719
EE 359 Electronic Circuits
Wien bridge w/ Amp. Stabil.
limiter used for amplitude control.
October 19, 200720
EE 359 Electronic Circuits
Alternate Wien bridge stabil.
October 19, 200721
EE 359 Electronic Circuits
Phase Shift Oscillator
October 19, 200722
EE 359 Electronic Circuits
Phase Shift. Osc. W/ Stabil.
October 19, 200723
EE 359 Electronic Circuits
Quad Osc. Circuit
October 19, 200724
EE 359 Electronic Circuits
Active Tuned Osc.
October 19, 200725
EE 359 Electronic Circuits
OPAMP based Tuned Amp. Osc.
October 19, 200726
EE 359 Electronic Circuits
Colpitts and Hartley Oscillators
October 19, 200727
EE 359 Electronic Circuits
Equiv. CktTo simplify the analysis, neglect Cm and rp
Consider Cp to be part of C2, and include ro in R.
October 19, 200728
EE 359 Electronic Circuits
Collpits Oscillator
October 19, 200729
EE 359 Electronic Circuits
Piezzoelectric Crystal
October 19, 200730
EE 359 Electronic Circuits
Pierce Oscillator
CMOS inverter as an amplifier.
October 19, 200731
EE 359 Electronic Circuits
Bistable Operation
