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EE142 Lecture25
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Amin ArbabianJan M. Rabaey
Lecture 25Negative Resistance View, Oscillator Circuits
EE142 – Fall 2010
Nov. 30th, 2010
University of California, Berkeley
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Review
Analyzed amplitude limiting mechanisms and steady-state oscillation conditions
Amplitude stability
Life-cycle of an oscillator going to start-up, amplitude limitations and finally stable output
Today: Negative resistance view of oscillators, differential oscillators, VCOs and crystal oscillators.
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Negative Resistance Perspective
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Oscillator Stability
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Negative Resistance LC Oscillator
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Oscillation Condition
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One-Port View of a General Oscillator
Bias not shown
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Colpitts Oscillator
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Colpitts Oscillator (2)
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Clapp Oscillator
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Clapp Oscillator (2)
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MOS Oscillators
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Differential Oscillators
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Negative Conductance of Cross-Coupled Pair
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Cross-Coupled Oscillator
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Other MOS Differential Oscillators
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BJT Differential Oscillator
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Virtual Ground
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Voltage-Controlled Oscillators
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PN Junction Varactors
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Doping Profile
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Varactor-Tuned LC Oscillator
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Clapp VCO
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Varactor-Tuned Differential Oscillator
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Varactor-Tuned Differential Oscillator (2)
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MOS Varactors
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MOS Varactors (2)
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Accumulation Mode MOS Varactors (A-MOS)
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Switched Capacitor Varactors
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Crystal Oscillators
The piezoelectric crystal is an electro-mechanical device with a sharp frequency selective response.
Equivalent Q > 10,000 are available.
The piezoelectric material exhibits a transduction between mechanical strain and electric charge.
Very good stability and low temperature coefficient.
Example:f=1.59 MHz (series)R = 125 Ω, L = 250 mH, C = 40 fF, Co = 4 pF
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Crystal Oscillators