1. Fundamentals of
RF Systems
조용희조용희

2. Fundamentals of RF SystemsFundamentals of RF Systems
전자파연구실전자파연구실2
1. Microwave systems
Transmission
  Information
- Channel bandwidth
- Base band
- Inefficient wave radiation
 Modulation – center frequency
Time domain Frequency domain
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3. Fundamentals of RF SystemsFundamentals of RF Systems
전자파연구실전자파연구실3
Why’s modulation need?
  Transmission efficiency
- Multiplexing
- Antenna length: wavelength
- Wave radiation: comparison with DC
Battery: DC
Antenna: AC
1. Microwave systems

4. Fundamentals of RF SystemsFundamentals of RF Systems
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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5. Fundamentals of RF SystemsFundamentals of RF Systems
전자파연구실전자파연구실5
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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6. Fundamentals of RF SystemsFundamentals of RF Systems
전자파연구실전자파연구실6
Microwave transceiver
  Duplexer: bandpass filter or switch
- Loss, tx suppression, channel selection
IF: superheterodyne
No IF: direct conversion
1. Microwave systems
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7. Fundamentals of RF SystemsFundamentals of RF Systems
전자파연구실전자파연구실7
FDMA (FDM Access)
1. Microwave systems
  Resource: frequency
 Guard band
 Simple transceiver
 Interference

8. Fundamentals of RF SystemsFundamentals of RF Systems
전자파연구실전자파연구실8
DS(Direct Sequence)-CDMA
1. Microwave systems
QPSK: Quadrature Phase Shift Keying

9. Fundamentals of RF SystemsFundamentals of RF Systems
전자파연구실전자파연구실9
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 η=

10. Fundamentals of RF SystemsFundamentals of RF Systems
전자파연구실전자파연구실10
2. Antennas
Dipole antenna
  Simple but long structure
 Low efficiency
Microstrip type

11. Fundamentals of RF SystemsFundamentals of RF Systems
전자파연구실전자파연구실11
Handy phone antenna
Helical antenna
2. Antennas
  Complicated structure
 Medium efficiency

12. Fundamentals of RF SystemsFundamentals of RF Systems
전자파연구실전자파연구실12
Antenna simulation
Ansoft: Ensemble
CST: MWS
Ansoft: HFSS
2. Antennas

13. Fundamentals of RF SystemsFundamentals of RF Systems
전자파연구실전자파연구실13
Wave propagation
}Re{
}Re{
)cos(),(
)(
tjzjj
o
ztj
o
o
eeeV
eV
ztVtzV
ωβφ
φβω
φβω
−
+−
=
=
+−=
3. Tx line theory

14. Fundamentals of RF SystemsFundamentals of RF Systems
전자파연구실전자파연구실14
Distributed element
  Lumped element: R, L, C
  Distributed element: tx line
3. Tx line theory

15. Fundamentals of RF SystemsFundamentals of RF Systems
전자파연구실전자파연구실15
Wave solution
  Traveling wave solution
- Voltage:
- Current:
zz
s eVeVzV γγ −−+
+= 00)(
zz
s eIeIzI γγ −−+
−= 00)(
)())((
)(
2
2
zVCjGLjR
dz
zVd
s
s
ωω ++=
))(( CjGLjRj ωωβαγ ++=+=
3. Tx line theory

16. Fundamentals of RF SystemsFundamentals of RF Systems
전자파연구실전자파연구실16
Characteristic impedance
  Important parameter in tx line:
-
-
CjG
LjR
Z
ω
ω
+
+
=0
−
−
+
+
==
0
0
0
0
0
I
V
I
V
Z
3. Tx line theory
0Z

17. Fundamentals of RF SystemsFundamentals of RF Systems
전자파연구실전자파연구실17
Reflection coefficient
0
0
0
11 ||
ZZ
ZZ
V
V
e
L
Loj
+
−
==Γ=Γ +
−
φ

  Voltage wave continuity conditions
 Current wave continuity conditions
3. Tx line theory

18. Fundamentals of RF SystemsFundamentals of RF Systems
전자파연구실전자파연구실18
Wave power
( ) ( )2
0
2
0*
1
2
Re
2
1
Γ−==
+
Z
V
VIP
3. Tx line theory

19. Fundamentals of RF SystemsFundamentals of RF Systems
전자파연구실전자파연구실19
SWR (Standing Wave Ratio)
  SWR: field theory
 VSWR (Voltage SWR): tx line theory
||1
||1
min
max
Γ−
Γ+
=
=
V
V
s
Experiment
3. Tx line theory

20. Fundamentals of RF SystemsFundamentals of RF Systems
전자파연구실전자파연구실20
Smith chart
 Graphical method
 Essential diagram for
microwave engineering

P. Smith in 1939
3. Tx line theory

21. Fundamentals of RF SystemsFundamentals of RF Systems
전자파연구실전자파연구실21
Induction of Smith chart
 S-parameter: reflection
coefficient
 |S11| = 0: all transmission
 |S11| = 1: all reflection

3. Tx line theory

22. Fundamentals of RF SystemsFundamentals of RF Systems
전자파연구실전자파연구실22
VNA (Vector Network Analyzer)
 Measurement equipment
 Reflection coefficients
with frequency sweep

3. Tx line theory

23. Fundamentals of RF SystemsFundamentals of RF Systems
전자파연구실전자파연구실23
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

24. Fundamentals of RF SystemsFundamentals of RF Systems
전자파연구실전자파연구실24
Antenna impedance
  Antenna impedance (not infinity) matching
 No reflection, power efficiency
Handy phone antenna
3. Tx line theory

25. Fundamentals of RF SystemsFundamentals of RF Systems
전자파연구실전자파연구실25
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

26. Fundamentals of RF SystemsFundamentals of RF Systems
전자파연구실전자파연구실26
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

27. Fundamentals of RF SystemsFundamentals of RF Systems
전자파연구실전자파연구실27
Microstrip line
3. Tx line theory
  Quasi-TEM line
 Easy fabrication: etching
 Substrate
 Characteristic impedance

28. Fundamentals of RF SystemsFundamentals of RF Systems
전자파연구실전자파연구실28
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

29. Fundamentals of RF SystemsFundamentals of RF Systems
전자파연구실전자파연구실29
Etching: PCB (Printed Circuit
Board)
  FR4, RT/duroid 5880 (6010 …)
 Film
 Photoresist (PR)
 Toluene
 Ultraviolet
 Iron chloride
3. Tx line theory

30. Fundamentals of RF SystemsFundamentals of RF Systems
전자파연구실전자파연구실30
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

31. Fundamentals of RF SystemsFundamentals of RF Systems
전자파연구실전자파연구실31
Wire bonding for bare chip
Wire bonding vs.
soldering

4. Amplifier

32. Fundamentals of RF SystemsFundamentals of RF Systems
전자파연구실전자파연구실32
Bias design
 Assignment of AC and DC path
4. Amplifier

33. Fundamentals of RF SystemsFundamentals of RF Systems
전자파연구실전자파연구실33
S2P file: S-parameter information
 Input impedance: S11
 Output impedance: S22
 Gain: S21
 Isolation: S12

4. Amplifier

34. Fundamentals of RF SystemsFundamentals of RF Systems
전자파연구실전자파연구실34
Impedance matching
 Lumped elements (L or C)
 Stub matching
 Conjugate matching: maximum power transfer
 Noise matching: low noise

( )*
LL ZZ →
4. Amplifier

35. Fundamentals of RF SystemsFundamentals of RF Systems
전자파연구실전자파연구실35
Block diagram of cellular phone
 LNA (Low Noise Amplifier), PA (Power
Amplifier), Mixer, VCO, switch
 Filter, duplexer

4. Amplifier

36. Fundamentals of RF SystemsFundamentals of RF Systems
전자파연구실전자파연구실36
Digital RF system
Transmitter and receiver
4. Amplifier

37. Fundamentals of RF SystemsFundamentals of RF Systems
전자파연구실전자파연구실37
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

38. Fundamentals of RF SystemsFundamentals of RF Systems
전자파연구실전자파연구실38
 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
SNR
NF ==

39. Fundamentals of RF SystemsFundamentals of RF Systems
전자파연구실전자파연구실39
Simulation of LNA
Port
OUT
Num=2
Port
IN
Num=1
C
C2
C=1.0pF
C
C1
C=1.0pF
L
L3
R=
L=1.0nH
L
L2
R=
L=1.0nH
TSMC_CM025RF_PMOS_RF
PMOS_RF1
finger=16
width=10um
length=0.24um
Type=2.5Vtwin-well
TSMC_CM025RF_NMOS
NMOS2
Width=0.30um
Length=0.24um
Type=2.5V_nom
L
L1
R=
L=1.0nH
R
R3
R=50Ohm
R
R2
R=50OhmTSMC_CM025RF_NMOS
NMOS1
Width=0.30um
Length=0.24um
Type=2.5V_nom
R
R1
R=50Ohm
HP
ADS (Advanced Design System)

 AC and DC path
4. Amplifier

40. Fundamentals of RF SystemsFundamentals of RF Systems
전자파연구실전자파연구실40
HPA (High Power Amplifier)
 Output power (P1dB), power gain
 Linearity (OIP3)
 Efficiency (PAE)
 Temperature

Power amplifier scheme
4. Amplifier

41. Fundamentals of RF SystemsFundamentals of RF Systems
전자파연구실전자파연구실41
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


42. Fundamentals of RF SystemsFundamentals of RF Systems
전자파연구실전자파연구실42
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

43. Fundamentals of RF SystemsFundamentals of RF Systems
전자파연구실전자파연구실43
Power divider
 Division of power: scattering matrix
 Lossless system
-
- Scattering matrix: unitary matrix

3-port networks 5-port networks












−−−
−−
−
=
ββαα
βαβα
αα
222
22
2
lossy
11
1
10
S

[ ] [ ] [ ] [ ]** −−++
= VVVV
TT
5. Filter

44. Fundamentals of RF SystemsFundamentals of RF Systems
전자파연구실전자파연구실44
T-junction power divider
 Simple 3-port network
 Waveguide or microstrip line
 Lossless or all-port matched network

portat 021in YYYjBY ++=
5. Filter
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45. Fundamentals of RF SystemsFundamentals of RF Systems
전자파연구실전자파연구실45
Frequency conversion
  Mixer
 VCO: Voltage Controlled Oscillator
 PLL: Phase Locked Loop
 TCXO: Temperature Compensated Crystal
Oscillator
6. IF conversion
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