impedance transformation
DESCRIPTION
Impedance Transformation. Topics. Quality Factor Series to parallel conversion Low-pass RC High-pass RL Bandpass Loaded Q Impedance Transformation Coupled Resonant Circuit Recent implementation, if time permits. Quality Factor. Quality Factor. Q is dimensionless. - PowerPoint PPT PresentationTRANSCRIPT
![Page 1: Impedance Transformation](https://reader035.vdocuments.mx/reader035/viewer/2022081512/56813edf550346895da9547e/html5/thumbnails/1.jpg)
Impedance Transformation
![Page 2: Impedance Transformation](https://reader035.vdocuments.mx/reader035/viewer/2022081512/56813edf550346895da9547e/html5/thumbnails/2.jpg)
Topics
• Quality Factor• Series to parallel conversion• Low-pass RC• High-pass RL• Bandpass• Loaded Q• Impedance Transformation• Coupled Resonant Circuit–Recent implementation, if time
permits
![Page 3: Impedance Transformation](https://reader035.vdocuments.mx/reader035/viewer/2022081512/56813edf550346895da9547e/html5/thumbnails/3.jpg)
Quality Factor
![Page 4: Impedance Transformation](https://reader035.vdocuments.mx/reader035/viewer/2022081512/56813edf550346895da9547e/html5/thumbnails/4.jpg)
Quality Factor
Q is dimensionless
![Page 5: Impedance Transformation](https://reader035.vdocuments.mx/reader035/viewer/2022081512/56813edf550346895da9547e/html5/thumbnails/5.jpg)
Quality factor of an inductor
(Imax)
= =ω=→ =
Q=(ωL)/R
Please note that Qis also equal to Q=Im(Z)/Re(Z)
![Page 6: Impedance Transformation](https://reader035.vdocuments.mx/reader035/viewer/2022081512/56813edf550346895da9547e/html5/thumbnails/6.jpg)
Quality factor of Parallel RL circuit
Q=Im(Z)/Re(Z)
Z==
Q=ωL(Rp)2/(ω2L2Rp)=Rp/ωL
![Page 7: Impedance Transformation](https://reader035.vdocuments.mx/reader035/viewer/2022081512/56813edf550346895da9547e/html5/thumbnails/7.jpg)
Quality factor of a Capacitor
= =ω=→ =
Q=ωCR
Please note that Qis also equal to Q=Im(Z)/Re(Z)
Z is the impedanceof parallel RC
![Page 8: Impedance Transformation](https://reader035.vdocuments.mx/reader035/viewer/2022081512/56813edf550346895da9547e/html5/thumbnails/8.jpg)
Quality factor of a Capacitor in Series with a Resistor
Q=1/(ωCRS)
Please note that Qis also equal to Q=Im(Z)/Re(Z)
Z is the impedanceof series RC
![Page 9: Impedance Transformation](https://reader035.vdocuments.mx/reader035/viewer/2022081512/56813edf550346895da9547e/html5/thumbnails/9.jpg)
Low-Pass RC Filter
![Page 10: Impedance Transformation](https://reader035.vdocuments.mx/reader035/viewer/2022081512/56813edf550346895da9547e/html5/thumbnails/10.jpg)
High-Pass Filter
lpf= pf
𝐿=𝑅2𝐶
![Page 11: Impedance Transformation](https://reader035.vdocuments.mx/reader035/viewer/2022081512/56813edf550346895da9547e/html5/thumbnails/11.jpg)
LPF+HPF
lpf= pf
![Page 12: Impedance Transformation](https://reader035.vdocuments.mx/reader035/viewer/2022081512/56813edf550346895da9547e/html5/thumbnails/12.jpg)
LPF+HPF (Magnified)
![Page 13: Impedance Transformation](https://reader035.vdocuments.mx/reader035/viewer/2022081512/56813edf550346895da9547e/html5/thumbnails/13.jpg)
Resistor Removed
![Page 14: Impedance Transformation](https://reader035.vdocuments.mx/reader035/viewer/2022081512/56813edf550346895da9547e/html5/thumbnails/14.jpg)
Design Intuition
![Page 15: Impedance Transformation](https://reader035.vdocuments.mx/reader035/viewer/2022081512/56813edf550346895da9547e/html5/thumbnails/15.jpg)
Circuit Quality Factor
Q=3.162/(5.129-1.95)=0.99
![Page 16: Impedance Transformation](https://reader035.vdocuments.mx/reader035/viewer/2022081512/56813edf550346895da9547e/html5/thumbnails/16.jpg)
Mathematical Analysis
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Transfer Function of a Bandpass Filter
Resonant frequency
![Page 18: Impedance Transformation](https://reader035.vdocuments.mx/reader035/viewer/2022081512/56813edf550346895da9547e/html5/thumbnails/18.jpg)
Cutoff Frequency
![Page 19: Impedance Transformation](https://reader035.vdocuments.mx/reader035/viewer/2022081512/56813edf550346895da9547e/html5/thumbnails/19.jpg)
Bandwidth Calculation
𝑄=ω𝑜𝑅𝐶
![Page 20: Impedance Transformation](https://reader035.vdocuments.mx/reader035/viewer/2022081512/56813edf550346895da9547e/html5/thumbnails/20.jpg)
Equivalent Circuit Approach
At resonant frequency, XP=1/(ωoCp)
![Page 21: Impedance Transformation](https://reader035.vdocuments.mx/reader035/viewer/2022081512/56813edf550346895da9547e/html5/thumbnails/21.jpg)
Effect of the Source Resistance
Q=3.162/(0.664)=4.76
![Page 22: Impedance Transformation](https://reader035.vdocuments.mx/reader035/viewer/2022081512/56813edf550346895da9547e/html5/thumbnails/22.jpg)
Effect of the Load Resistor
6 dB drop at resonance due to the resistive divider.
Q=3.162/(7.762-1.318)=0.49
The loading will reduce the circuit Q.
![Page 23: Impedance Transformation](https://reader035.vdocuments.mx/reader035/viewer/2022081512/56813edf550346895da9547e/html5/thumbnails/23.jpg)
Summary
Q=0.99
Q=4.79
Q=0.49
𝑄=ω𝑜𝑅𝐶
![Page 24: Impedance Transformation](https://reader035.vdocuments.mx/reader035/viewer/2022081512/56813edf550346895da9547e/html5/thumbnails/24.jpg)
Design Constraints
• Specs– Resonant Frequency: 2.4 GHz– RS=50 Ohms
– RL=Infinity
• List Q, C & L
𝑄=ω𝑜𝑅𝐶
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ValuesQ C L
0.5 0.663 pF
6.63 nH
1 1.326 pF
3.315 nH
10 13.26 pF
331.5 pH
Specs:• Resonant Frequency: 2.4 GHz• RS=50 Ohms• RL=Infinity
![Page 26: Impedance Transformation](https://reader035.vdocuments.mx/reader035/viewer/2022081512/56813edf550346895da9547e/html5/thumbnails/26.jpg)
Design Example
Q=2.4/(2.523-2.286)=10.12
BW=237 MHz
![Page 27: Impedance Transformation](https://reader035.vdocuments.mx/reader035/viewer/2022081512/56813edf550346895da9547e/html5/thumbnails/27.jpg)
Implement the Inductor
![Page 29: Impedance Transformation](https://reader035.vdocuments.mx/reader035/viewer/2022081512/56813edf550346895da9547e/html5/thumbnails/29.jpg)
Resistance of Inductor
• R=Rsh(L/W)
– Rsh is the sheet resistance
– Rsh is 22 mOhms per square for W=6um.– If the outer diameter is 135 um, the length is
approximately 135um x4=540 um.– R=22 mOhms x (540/6)=1.98 Ohms
•
Q=(ωL)/R=(2π2.4G0.336 nH)/1.98 Ω=2.56
![Page 30: Impedance Transformation](https://reader035.vdocuments.mx/reader035/viewer/2022081512/56813edf550346895da9547e/html5/thumbnails/30.jpg)
Include Resistor In the Tank Circuitry
Q=2.427/(3.076-1.888)=2.04
Inclusion of parasitic resistancereduces the circuit Q from 10.
![Page 31: Impedance Transformation](https://reader035.vdocuments.mx/reader035/viewer/2022081512/56813edf550346895da9547e/html5/thumbnails/31.jpg)
Series to Parallel Conversion
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Series to Parallel Conversion
We have an open at DC!
We have resistor RP at DC!
It is NOT POSSIBLE to make these two circuitsIdentical at all frequencies, but we can makethese to exhibit approximate behavior at certain frequencies.
![Page 33: Impedance Transformation](https://reader035.vdocuments.mx/reader035/viewer/2022081512/56813edf550346895da9547e/html5/thumbnails/33.jpg)
Derivation
QS=QP
![Page 34: Impedance Transformation](https://reader035.vdocuments.mx/reader035/viewer/2022081512/56813edf550346895da9547e/html5/thumbnails/34.jpg)
RP
QS=1/(ωCSRS)
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Cp
QS=1/(ωCSRS)
![Page 36: Impedance Transformation](https://reader035.vdocuments.mx/reader035/viewer/2022081512/56813edf550346895da9547e/html5/thumbnails/36.jpg)
Summary
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Series to Parallel Conversion for RL Circuits
![Page 38: Impedance Transformation](https://reader035.vdocuments.mx/reader035/viewer/2022081512/56813edf550346895da9547e/html5/thumbnails/38.jpg)
Resistance of Inductor
• R=Rsh(L/W)
– Rsh is the sheet resistance
– Rsh is 22 mOhms per square for W=6um.– If the outer diameter is 135 um, the length is
approximately 135um x4=540 um.– R=22 mOhms x (540/6)=1.98 Ohms
•
Q=(ωL)/R=(2π2.4G0.336 nH)/1.98 Ω=2.56
Rp=RS(1+QSQS)=1.98 Ohms(1+2.56x2.56)=14.96 OhmsLp=LS(1+1/(QSQS))=331.5 pH(1+1/2.56/2.56)=382.08 nH
![Page 39: Impedance Transformation](https://reader035.vdocuments.mx/reader035/viewer/2022081512/56813edf550346895da9547e/html5/thumbnails/39.jpg)
Insertion Loss Due to Inductor Resistance
At resonant frequency, voltage divider ratio is14.96Ω/(14.96 Ω+50 Ω)=0.2303
Convert to loss in dB, 20log10(0.23)=-12.75 dB
![Page 40: Impedance Transformation](https://reader035.vdocuments.mx/reader035/viewer/2022081512/56813edf550346895da9547e/html5/thumbnails/40.jpg)
Use Tapped-C Circuit to Fool the Tank into Thinking It Has High RS
![Page 41: Impedance Transformation](https://reader035.vdocuments.mx/reader035/viewer/2022081512/56813edf550346895da9547e/html5/thumbnails/41.jpg)
Derivation
![Page 42: Impedance Transformation](https://reader035.vdocuments.mx/reader035/viewer/2022081512/56813edf550346895da9547e/html5/thumbnails/42.jpg)
Previous Design ValuesQ C L
0.5 0.663 pF
6.63 nH
1 1.326 pF
3.315 nH
10 13.26 pF
331.5 pH
Specs:• Resonant Frequency: 2.4 GHz• RS=50 Ohms• RL=Infinity
![Page 43: Impedance Transformation](https://reader035.vdocuments.mx/reader035/viewer/2022081512/56813edf550346895da9547e/html5/thumbnails/43.jpg)
Design Problem
Knowns & UnknownsKnowns: • RS=50 Ohms• CT=13.26 pFUnknowns:• C1/C2
• R’S
![Page 44: Impedance Transformation](https://reader035.vdocuments.mx/reader035/viewer/2022081512/56813edf550346895da9547e/html5/thumbnails/44.jpg)
Calculations
• CT=C1/(1+C1/C2)
• C1=CT(1+C1/C2)
C1/C2 R’S C1 C2
1 200 Ω 26.52 pF 26.52 pF
2 450Ω 39.78 pF 19.89 pF
3 800Ω 53.04 pF 17.68 pF
![Page 45: Impedance Transformation](https://reader035.vdocuments.mx/reader035/viewer/2022081512/56813edf550346895da9547e/html5/thumbnails/45.jpg)
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Include the Effect of Parasitic Resistor