EE 359 Electronic Circuits
Filters and Tuned Amplifiers Second order LCR resonator Second order Active Filters based on Inductor Replacement
Signal Generators Oscillators
October 19, 2007
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EE 359 Electronic Circuits
HW
Due today 12.7, 12.9,12.28, 12.34 Review October 26 Quiz#2 October 29
October 19, 2007
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EE 359 Electronic Circuits
Second Order LCR Resonator
• LCR Resonator V0 1 1 = = I Y 1 / sL + sC + 1 / R s/C = 2 s + s (1 / CR ) + 1 / LC
ω 02 = 1 / LC ω 0 / Q = 1 / CR ω 0 = 1 / LC Q = ω 0CR
• Excite parallel LCR resonator – Determine natural modes (I.e. poles of response function)
October 19, 2007
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EE 359 Electronic Circuits
Transmission Zeros LPF
• Where to inject iput signal Vi ? T ( s) =
V0 ( s ) Z 2 ( s) = Vi ( s) Z1 ( s) + Z 2 ( s )
• Transmission zeros are when Z2(s) are zero (if Z1
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EE 359 Electronic Circuits
Realization of Low Pass Function
• Transmission zeros are when series impedance becomes infinite. 1 sL → ∞ ⇒ s → ∞ ⇒ →0 sC + 1 / R V0 Z2 Y1 1 / sL T ( s) = = = = Vi Z1 + Z 2 Y1 + Y2 1 / sL + sC + 1 / R
October 19, 2007
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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. V0 a2 s 2 T ( s) = = 2 Vi s + s( ω 0 / Q ) + ω 02
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EE 359 Electronic Circuits
Bandpass Filter
• Zero at s=0 due to shunt inductor, s=infinity due to shunt capacitor. T ( s) =
V0 s (1 / CR ) = 2 Vi s + s (1 / CR ) + 1 / LC
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EE 359 Electronic Circuits
Inductance Simulation
• Use opamps instead of inductor!
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EE 359 Electronic Circuits
Low Pass Filter
V0 ( s ) Z 2 ( s) T ( s) = = Vi ( s ) Z1 ( s ) + Z 2 ( s )
V0 Z2 Y1 1 / sL T ( s) = = = = Vi Z1 + Z 2 Y1 + Y2 1 / sL + sC + 1 / R October 19, 2007
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EE 359 Electronic Circuits
High Pass Filter
•
V0 a2 s 2 T ( s) = = 2 Vi s + s( ω 0 / Q ) + ω 02
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EE 359 Electronic Circuits
Bandpass Filter
•
T ( s) =
October 19, 2007
V0 s (1 / CR ) = 2 Vi s + s (1 / CR ) + 1 / LC 11
EE 359 Electronic Circuits
Low Pass Notch filter
•
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EE 359 Electronic Circuits Second-order narrow-band bandpass filter by transforming a Second-order narrow-band first-order low-pass filter 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 + jω0 and adding a complex conjugate pole results in the poles of the secondorder bandpass filter. (c) Magnitude response of the firs-order low-pass filter. (d) Magnitude response of the second-order bandpass filter.
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EE 359 Electronic Circuits Poles and the frequency response of a fourth-order stagger-tuned narrow-band bandpass amplifier by transforming a second-order lowpass .
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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
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EE 359 Electronic Circuits
Oscillator-frequency stability
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EE 359 Electronic Circuits
Limiter Ckt Comparator
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EE 359 Electronic Circuits
Wien-bridge oscillator
without amplitude stabilization .
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EE 359 Electronic Circuits
Wien bridge w/ Amp. Stabil.
limiter used for amplitude control.
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EE 359 Electronic Circuits
Alternate Wien bridge stabil.
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EE 359 Electronic Circuits
Phase Shift Oscillator
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EE 359 Electronic Circuits
Phase Shift. Osc. W/ Stabil.
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EE 359 Electronic Circuits
Quad Osc. Circuit
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EE 359 Electronic Circuits
Active Tuned Osc.
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EE 359 Electronic Circuits
OPAMP based Tuned Amp. Osc.
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EE 359 Electronic Circuits
Colpitts and Hartley Oscillators
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EE 359 Electronic Circuits
Equiv. Ckt
To simplify the analysis, neglect Cm and rp Consider Cp to be part of C2, and include ro in R.
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EE 359 Electronic Circuits
Collpits Oscillator
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EE 359 Electronic Circuits
Piezzoelectric Crystal
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EE 359 Electronic Circuits
Pierce Oscillator
CMOS inverter as an amplifier.
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EE 359 Electronic Circuits
Bistable Operation
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