1. 10. Noise and active RF components

2. 10.1 Noise in microwave circuit전자
Lattice scattering
원자핵

3. Noise power, noise voltage
Measurement setup:
Spectrum analyzer
Noise power :
Planck 법칙에 의한 radiation
Planck 법칙에 의한 복사 전력
k: Boltzmann constant (1.38e-23 J/K)
B : bandwidth in Hz
T : Absolute temperature in Kelvin
R : resistance in Ω.
Noise voltage :

4. Equivalent noise temperature: Te
Equivalent noise power
Figure (p. 490) The equivalent noise temperature, Te, of an arbitrary white noise source.

5. Equivalent noise temperature of an amplifier
Figure (p. 491) Defining the equivalent noise temperature of a noisy amplifier. (a) Noisy amplifier. (b) Noiseless amplifier.

6. Noise temperature
Figure (p. 492) The Y-factor method for measuring the equivalent noise temperature of an amplifier.

7. Dynamic range of an amplifier
Power output threshold
입력신호와 상관없이 회로 자체에서 생기는 noise로 인한 출력

8. Noise figure
Noise figure :
회로 자체에서 생기는 noise로 인해 SNR이 얼마나 나빠졌는가의 척도

9. Noise figure of a lossy network
Lossy network의 noise figure는 loss와 같다.
Noise는 loss에 의해 감쇄되지 않고 온도와 관련됨.

10. Noise figure of a cascaded system

12. Example 10.2 Noise analysis of a wireless receiver
아래 블록 다이어그램은 무선 단말기의 수신 부이다. Feeding antenna의 noise temperature가 150K일 때 출력 신호의 noise 전력을 구하라. 또한 출력 신호를 구분 가능한 최소의 SNR이 20dB라고 할 때 입력신호의 최소 전압도 구하라.

13. 10.2 Dynamic range and inter-modulation distortion
DC output
Linear output
Squared output

15. Gain compression
a3의 부호는 a1과 반대가 되는 경우가 많아서 입력 전압이 커질수록 gain이 줄어든다.

16. Inter-modulation distortion

17. Output signal from a non-ideal amplifier
입력 신호
출력 신호
Filter로 제거 가능
Filter로 제거 가능
Filter로 제거 불가능

18. Third-Order intercept point
주파수 ω1 성분의 power
주파수 2ω1 - ω2 성분의 power
출력 주파수 ω1 , 2ω1 - ω2 두 성분의 power가 같아질 때 입력 전력.

20. Dynamic range Linear dynamic range : P1dB /N0
Spurious free dynamic range :
Pω1/P2ω1-ω2 (P2ω1-ω2 = N0)
Figure (p. 506) Illustrating linear dynamic range and spurious free dynamic range.

21. Intercept point of a cascaded system

22. Example 10.5
For amplifier
For mixer

23. 10.3 RF diode characteristics
Diode 의 비선형 효과를 이용하여 signal detection, demodulation, switching, frequency multiplication, oscillation 회로를 만든다.
Figure (p. 510) Basic frequency conversion operations of rectification, detection, and mixing. (a) Diode rectifier. (b) Diode detector. (c) Mixer.

24. Diode 종류 (2) Schottky diode (1) pn-junction diode
Turn on voltage : 0.7V
Turn on voltage : 0.25V
high frequency에서 동작을 위해 pn-junction diode보다 Schottky barrier diode를 사용한다.
pn-junction은 reverse recovery time으로 ~100ns 이상의 switching time이 필요하나 Schottky diode는 ~100ps 도 가능.

25. Unbiased PN junction ID : Diffusion current. IS : Drift current
Electric field

26. Minority-carrier distribution in a forward-biased pn junction
Minority-carrier distribution in a forward-biased pn junction. It is assumed that the p region is more heavily doped than the n region; NA @ ND.

27. (3) p-i-n diode
등가 회로
pn-junction 사이에 intrinsic (doping이 안된 상태) 반도체가 있어 역방향일 때 C (capacitance)를 더욱 줄여주고, 순방향일 때 직렬 저항을 조절 가능하게 함.
RF switch

28. Diode package

29. RF diode i~v characteristics
Large signal model
n=1.2 for Schottky barrier diode, n=2 for point contact silicon diode
Small signal model approximation
DC bias current

30. Contact, current-spreading resistance Shunt capacitance
lead inductance
Contact, current-spreading resistance
Shunt capacitance
Figure (p. 511) Equivalent AC circuit model for a Schottky diode.
Junction capacitance, junction resistance

31. Diode rectifiers
Bias current
DC rectified current

32. Diode detectors m : modulation index, 0<m<1
입력 power에 비례한 출력이므로 square law detector

33. Diode detector output
Figure (p. 513) Square-law region for a typical diode detector.

34. Pin diodes and control circuits
Microwave switch
mechanical type: high power, slow switching speed
electronic type : PIN diode, FET. High speed operation (~10ns)

35. Equivalent circuit : typical values
Figure (p. 515) Equivalent circuits for the ON and OFF states of a PIN diode. (a) Reverse bias (OFF) state. (b) Forward bias (ON) state.

36. Single-pole PIN diode switches
Figure (p. 515) Single-pole PIN diode switches. (a) Series configuration. (b) Shunt configuration.

37. Switch equivalent circuits
Figure (p. 516) Simplified equivalent circuits for the series and shunt single-pole PIN diode switches. (a) Series switch. (b) Shunt switch.

38. Microwave network analysis
1-port network
2-port network

39. Device characterization
Impedance and Admittance Matrix
- Generalize Z concept to N-port
- Arbitrary N-port Network
Impedance matrix t2
V1+, I1+ t3 t1 t4
V1-, I1- t1 tN
VN+,IN+
VN-, IN-
Admittance matrix

40. Measurement of impedance parameter
Two port network + -
주파수가 높은 경우 open-circuit만들기 어려움. (parasitic capacitance 때문)
Admittance parameter인 경우는 short circuit만들기 어려움. (parasitic inductance때문)

41. Scattering Matrix - in accord with direct measurement
- incident, reflected & transmitted wave
- easy to adeve impedance matching at high frequency
All other part j≠k matched → no reflection
Vk→ 0
Sii reflection coefficient
Sji transmission coefficient

42. Measurement of S-parameters
Impedance matching 된 상태
Port 1
Port 2
Transfer switch
Source B R A
S-Parameter Test Set
DUT
Fwd
Rev

44. Example 4.4 S-parameter 계산
Port 1 2 ⅰ)
Thereby S11=0
Symmetry of circuit S22=0
ⅱ) since S11=S22=0 & part 2 is terminated with 50ohm

45. Pin diode phase shifters
A switched line phase shifter

46. Loaded line phase shifters
Basic circuit

47. Practical loaded-line phase shifter

49. A reflection phase shifter using a quadrature hybrid

50. 7.5 Quadrature hybrid coupler

51. 10.4 RF transistor characteristics
Table 10.2 Performance characteristics of microwave transistors
Device
Si BJT
Si CMOS
SiGe HBT
GaAs MESFET
GaAs HEMT
GaAs HBT
Frequency range (GHz) 10 20 30 40
100 60
Typical gain (dB)
10-15
10-20
5-20
Noise Figure (dB)
2.0 (2GHz)
1.0 (4GHz)
0.6
(8GHz)
1.0 (10GHz)
0.5
(12GHz)
4.0
Power capacity
High
Low
Medium
Cost
Single polarity power supply
Yes No

52. FETs 52
Figure (p. 523) (a) Cross section of a GaAs MESFET; (b) top view, showing drain, gate, and source contacts.

53. Equivalent circuit for a microwave FET
Common-source configuration
Unity gain frequency
(Short circuit current gain)

54. DC bias circuit
Figure (p. 524) (a) DC characteristics of a GaAs FET; (b) biasing and decoupling circuit for a GaAs FET.

55. BJTs
Figure (p. 525) (a) Cross section of a microwave silicon bipolar transistor; (b) top view, showing base and emitter contacts.

56. Equivalent circuit for a microwave BJT
Common-emitter configuration
Unity gain frequency

57. DC bias circuit
Figure (p. 526) (a) DC characteristics of a silicon bipolar transistor; (b) biasing and decoupling circuit for a bipolar transistor.
Zero가 되어 high frequency에서 oscillation가능성 있음.
저항 때문에 noise figure증가함.
Emitter는 GND에 연결되어 있는 형태가 많이 쓰임.

58. DC bias network - BJT
Collector current changes due to temperature variation
Ic doubles every 10℃ rise.
Ic when IE=0.

59. Example
온도가 올라가면 Ic가 커진다. 그러나 Rc가 큰 경우 변화는 미미하다.

62. Example

63. Active bias-BJT

66. Bias point selection-BJT

67. DC bias network – GaAs MESFET

69. Bias point selection

70. Active bias-GaAs

71. Figure 10-39 (p. 528) Layout of a hybrid microwave integrated circuit.

72. Figure (p. 528) Photograph of one of the 25,344 hybrid integrated T/R modules used in Raytheon’s Ground Based Radar system. This X-band module contains phase shifters, amplifiers, switches, couplers, a ferrite circulator, and associated control and bias circuitry. Courtesy of Raytheon Company, Lexington, MA.

73. Figure 10-41 (p. 530) Layout of a monolithic microwave integrated circuit.

74. Figure (p. 530) Photograph of a monolithic integrated X-band power amplifier. This circuit uses eight heterojunction bipolar transistors with power dividers/combiners at the input and output to produce 5 watts. Courtesy of M. Adlerstein and R. Wohlert, Raytheon Company.