Fundamentals of RF Systems
조용희조용희
Fundamentals of RF Fundamentals of RF SystemsSystems
전자파연구실전자파연구실2
1. Microwave systems
Transmission
Information- Channel bandwidth- Base band- Inefficient wave radiation
Modulation – center frequency
Time domain Frequency domain
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Fundamentals of RF Fundamentals of RF SystemsSystems
전자파연구실전자파연구실3
Why’s modulation need?
Transmission efficiency- Multiplexing- Antenna length: wavelength- Wave radiation: comparison with DC
Battery: DCAntenna: AC
1. Microwave systems
Fundamentals of RF Fundamentals of RF SystemsSystems
전자파연구실전자파연구실4
Microwave transmitter (Tx)
Up-conversion: frequency
)cos()cos(2
1)cos()cos( yxyxyx
BBf BBLO ff BBLO ff
1. Microwave systems
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Fundamentals of RF Fundamentals of RF SystemsSystems
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Microwave receiver (Rx)
Down-conversion: frequency
)cos()cos(2
1)cos()cos( yxyxyx
BBfBBIF ff BBLO ff
IFLO fff IFff
1. Microwave systems
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Fundamentals of RF Fundamentals of RF SystemsSystems
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Microwave transceiver
Duplexer: bandpass filter or switch- Loss, tx suppression, channel selection
IF: superheterodyneNo IF: direct conversion
1. Microwave systems
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FDMA (FDM Access)
1. Microwave systems
Resource: frequency Guard band Simple transceiver Interference
Fundamentals of RF Fundamentals of RF SystemsSystems
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DS(Direct Sequence)-CDMA
1. Microwave systems
QPSK: Quadrature Phase Shift Keying
Fundamentals of RF Fundamentals of RF SystemsSystems
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Fundamentals
Antenna gain: anisotropic radiation (G > 1)isotropic radiation (G = 1)
Directivity and efficiency: Angular beamwidth: 3dB
Radiation pattern [dBi]: dB isotropic
2. Antennas
DG
Fundamentals of RF Fundamentals of RF SystemsSystems
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2. Antennas
Dipole antenna
Simple but long structure Low efficiency
Microstrip type
Fundamentals of RF Fundamentals of RF SystemsSystems
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Handy phone antenna
Helical antenna
2. Antennas
Complicated structure Medium efficiency
Fundamentals of RF Fundamentals of RF SystemsSystems
전자파연구실전자파연구실12
Antenna simulation
Ansoft: Ensemble
CST: MWS
Ansoft: HFSS
2. Antennas
Fundamentals of RF Fundamentals of RF SystemsSystems
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Wave propagation
}Re{
}Re{
)cos(),()(
tjzjjo
ztjo
o
eeeV
eV
ztVtzV
3. Tx line theory
Fundamentals of RF Fundamentals of RF SystemsSystems
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Distributed element
Lumped element: R, L, C
Distributed element: tx line
3. Tx line theory
Fundamentals of RF Fundamentals of RF SystemsSystems
전자파연구실전자파연구실15
Wave solution
Traveling wave solution- Voltage:
- Current:
zzs eVeVzV 00)(
zzs eIeIzI 00)(
)())(()(
2
2
zVCjGLjRdz
zVds
s
))(( CjGLjRj
3. Tx line theory
Fundamentals of RF Fundamentals of RF SystemsSystems
전자파연구실전자파연구실16
Characteristic impedance
Important parameter in tx line:
-
-
CjG
LjRZ
0
0
0
0
00 I
V
I
VZ
3. Tx line theory
0Z
Fundamentals of RF Fundamentals of RF SystemsSystems
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Reflection coefficient
0
0
011 ||
ZZ
ZZ
V
Ve
L
Loj
Voltage wave continuity conditions Current wave continuity conditions
3. Tx line theory
Fundamentals of RF Fundamentals of RF SystemsSystems
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Wave power
2
0
2
0* 12
Re2
1
Z
VVIP
3. Tx line theory
Fundamentals of RF Fundamentals of RF SystemsSystems
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SWR (Standing Wave Ratio)
SWR: field theory VSWR (Voltage SWR): tx line theory
||1
||1min
max
V
Vs
Experiment
3. Tx line theory
Fundamentals of RF Fundamentals of RF SystemsSystems
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Smith chart
Graphical method
Essential diagram for microwave engineering
P. Smith in 1939
3. Tx line theory
Fundamentals of RF Fundamentals of RF SystemsSystems
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Induction of Smith chart
S-parameter: reflection coefficient
|S11| = 0: all transmission |S11| = 1: all reflection
3. Tx line theory
Fundamentals of RF Fundamentals of RF SystemsSystems
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VNA (Vector Network Analyzer)
Measurement equipment
Reflection coefficients with frequency sweep
3. Tx line theory
Fundamentals of RF Fundamentals of RF SystemsSystems
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Scattering matrix: Two-port network
Matrix definition: matched load
gain:
isolation:
reflection:, where
21
12
2211
2
1
2221
1211
2
1
S
S
SS
V
V
SS
SS
V
V
3. Tx line theory
Fundamentals of RF Fundamentals of RF SystemsSystems
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Antenna impedance
Antenna impedance (not infinity) matching No reflection, power efficiency
Handy phone antenna
3. Tx line theory
Fundamentals of RF Fundamentals of RF SystemsSystems
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Coaxial line
3. Tx line theory
Wide bandwidth (TEM) Characteristic impedance: 50 Ohms Shielding Conductor and dielectric loss Measurement RG (Radio Government) series
Coaxial line
Fundamentals of RF Fundamentals of RF SystemsSystems
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Connector
BNC (Bayonet Neill Concelman) connector SMA (SubMiniature type A) connector Type N connector Type K connector APC (Amphenol Precision Connector)
3. Tx line theory
Fundamentals of RF Fundamentals of RF SystemsSystems
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Microstrip line
3. Tx line theory
Quasi-TEM line Easy fabrication: etching Substrate Characteristic impedance
Fundamentals of RF Fundamentals of RF SystemsSystems
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Substrate
Relative permittivity Thickness of a substrate: mil (inch/1000) Thickness of a metal: oz (almost 1.4 mils) Loss: loss tangent Temperature
3. Tx line theory
Power amplifier module
Fundamentals of RF Fundamentals of RF SystemsSystems
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Etching: PCB (Printed Circuit Board)
FR4, RT/duroid 5880 (6010 …) Film Photoresist (PR) Toluene Ultraviolet Iron chloride
3. Tx line theory
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Selection of active device
4. Amplifier
pHEMT amplifier with package
Gain [dB]
Bandwidth [Hz]
Stability: oscillation
Noise figure [dB]: LNA
P1dB [dBm]: PA
Characteristics of active device: bias
Bare chip
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Wire bonding for bare chip
Wire bonding vs.soldering
4. Amplifier
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Bias design
Assignment of AC and DC path
4. Amplifier
Fundamentals of RF Fundamentals of RF SystemsSystems
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S2P file: S-parameter information
Input impedance: S11
Output impedance: S22
Gain: S21
Isolation: S12
4. Amplifier
Fundamentals of RF Fundamentals of RF SystemsSystems
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Impedance matching
Lumped elements (L or C)
Stub matching
Conjugate matching: maximum power transfer
Noise matching: low noise
*LL ZZ
4. Amplifier
Fundamentals of RF Fundamentals of RF SystemsSystems
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Block diagram of cellular phone
LNA (Low Noise Amplifier), PA (Power Amplifier), Mixer, VCO, switch
Filter, duplexer
4. Amplifier
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Digital RF system
Transmitter and receiver
4. Amplifier
Fundamentals of RF Fundamentals of RF SystemsSystems
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LNA (Low Noise Amplifier)
Noise figure: 2 dB Amplifier gain: 15 dB Return loss: 15 dB Reverse isolation: 20 dB Impedance matching: power and noise
4. Amplifier
Fundamentals of RF Fundamentals of RF SystemsSystems
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SNR: signal to noise ratio Noiseless system: NF = 1 Noisy system: NF > 1 Ground
Noise figure (NF)
4. Amplifier
in
out
out
in
out
in
N
N
S
S
SNR
SNRNF
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Simulation of LNA
PortOUTNum=2
PortINNum=1
CC2C=1.0 pF
CC1C=1.0 pF
LL3
R=L=1.0 nH
LL2
R=L=1.0 nH
TSMC_CM025RF_PMOS_RFPMOS_RF1
finger=16width=10 umlength=0.24 umType=2.5V twin-well
TSMC_CM025RF_NMOSNMOS2
Width=0.30 umLength=0.24 umType=2.5V_nom
LL1
R=L=1.0 nH
RR3R=50 Ohm
RR2R=50 OhmTSMC_CM025RF_NMOS
NMOS1
Width=0.30 umLength=0.24 umType=2.5V_nom
RR1R=50 Ohm
HP ADS (Advanced Design System)
AC and DC path
4. Amplifier
Fundamentals of RF Fundamentals of RF SystemsSystems
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HPA (High Power Amplifier)
Output power (P1dB), power gain Linearity (OIP3) Efficiency (PAE) Temperature
Power amplifier scheme
4. Amplifier
Fundamentals of RF Fundamentals of RF SystemsSystems
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Characteristics
5. Filter
2 port network: S parameters Pass band and stop band Return loss and insertion loss Ripple and selectivity (skirt) Pole and zero Group delay
Fundamentals of RF Fundamentals of RF SystemsSystems
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Classification
LPF (Low Pass Filter) HPF (High Pass Filter) BPF (Band Pass Filter) BSF (Band Stop Filter): notch filter
Duplexer: 2 BPF Diplexer: LPF and HPF
5. Filter
Fundamentals of RF Fundamentals of RF SystemsSystems
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Power divider
Division of power: scattering matrix Lossless system- - Scattering matrix: unitary matrix
3-port networks 5-port networks
222
22
2
lossy
11
1
10
S
** VVVVTT
5. Filter
Fundamentals of RF Fundamentals of RF SystemsSystems
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T-junction power divider
Simple 3-port network Waveguide or microstrip line Lossless or all-port matched network
port at 021in YYYjBY
5. Filter
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Frequency conversion
Mixer VCO: Voltage Controlled Oscillator PLL: Phase Locked Loop TCXO: Temperature Compensated Crystal
Oscillator
6. IF conversion
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